User Manual - Crystalonics Displays (P) Ltd

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User Manual

CDM - USER’S MANUAL CONTENTS I

FEATURES OF CRYSTALONICS DISPLAY MODULES II GENERAL VIEW OF AN LCD (A)

INTRODUCTION (B) ELECTRO OPTICAL CHARACTERISTICS OF THE LCD’S (C)BACKLIGHTING (D) PIN DETAILS (E) ORDERING INFORMATION III HARDWARE

DESCRIPTION (A) POWER SUPPLY REQUIREMENTS (B) INTERFACING (C) TIMING

ASPECTS OF LCD’S IV SOFTWARE DESCRIPTION (A) INTRODUCTION (B) INSTRUCTIONCODES (C) INITIALIZATION FLOW FOR 8 BIT AND 4 BIT LCD MODULES (D) FUNCTIONAL

DESCRIPTION OF THE CONTROLLER IC (E) DDRAM LOCATIONS (F) CGRAMPROGRAMMING (G) CHARACTER FONT TABLE V PRECAUTIONS (A) POWER SUPPLY

PRECAUTIONS (B) MECHANICAL PRECAUTIONS (C) ENVIRONMENTAL PRECAUTIONS(D) OPERATING PRECAUTIONS VI TROUBLESHOOTING

I FEATURES OF CRYSTALONICS DISPLAY MODULES q Displays Alphanumeric

Characters, Special symbols & characters q Easy interface with a 4-bit or 8-bit MCU q Built-in

Dot Matrix LCD Controller with font 5x8 or 5x10 Dots q Built in Display Data RAM (DD RAM),Character Generator RAM (CG RAM) and Character Generator ROM (CG ROM) q Automatic

power on Reset q Low power consumption q Various instruction functions q High contrast ratio qWide viewing angle q Rapid response time q With & without Backlight q High quality standards q

Long life q Custom made LCD’s q Wide temperature range * q C-Dot Approved * * Applies for

selected Modules only. II GENERAL VIEW OF AN LCD (A) INTRODUCTION The Liquid

Crystal Display (LCD) is a thin layer of ”Liquid Crystal Material” deposited between two

plates of glass. LCD’s have materials, which combine the properties of both Liquids and

Crystals. Rather than having a melting point, they have a temperature range with in which the

molecules are almost as mobile as they would be in a Liquid, but are grouped together in anordered form similar to a Crystal. An LCD consists of two glass panels, with the liquid crystalmaterial sandwiched in between them. The inner surfaces of the glass plates are coated with

transparent electrodes, which define the character, symbols or patterns to be displayed.Polymeric layers are present in between the electrodes and the liquid crystal, which makes

the liquid crystal molecules to maintain a defined orientation angle. There are polarizers on the

glass panels. These polarizers rotate the light rays passing through them to a definite angle in a

particular direction. When LCD is in the off state light rays are rotated by the two polarizers andthe liquid crystal, such that the light rays come out of the LCD without any orientation, and the

LCD appears transparent. When sufficient voltage is applied to the electrodes, the liquid crystal

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molecules would be aligned in a specific direction. The light rays, which are rotated by polarizerspassing through the LCD, would result in highlighting the specific character. Since LCD’s consume

less power they are compatible with low power electronic circuits, and can be powered for longdurations. The LCD’s have a long life and wide operating temperature range between -20°C and

+70°C. The LCD’s are lightweight with only a few millimeters thickness. LCD’s do not generate

light. So light is required to read the display. Hence Displays are readable both day and night byselecting a backlight option. LCD’s are extensively used in segment displays like Watches,

Calculators, Clock, Camera, Audio Equipments, Home Appliances, Instruments, Telephones,Automobiles, and Games etc. Recent advances in LCD technologies have resulted in LCD’s being

extensively used in telecommunications and consumer electronics. The LCD’s have even started

replacing Cathode Ray Tubes (CRTs) used for the display of text and graphics, and also in TV

applications. An LCD module is selected depending on § The size and format required in

displaying the desired information. § The optical characteristics that looks best in the module.

Alphanumeric modules display characters, numerals, symbols and some limited graphics. Interface

is achieved via a bi-directional, parallel ASCII data bus. Necessary features such as Character

generation RAM (CG RAM), Display Device RAM (DDRAM) addressing, cursor scrolling,

Blanking, User programmable fonts and Handshake are all included. These modules are the

simplest and most economic means to communicate between any micro system and the outsideworld. Alphanumeric modules ranges One, two or four character lines are possible. Most formats

are available in a variety of packages to meet various mounting requirements. Selecting the exactversion of an LCD once the format is decided is largely a subjective judgment. Color, fluid type

and backlighting determine the overall look of the display and often the appearance of the finalproduct. Operating condition such as temperature, lighting condition and available power are also

factors in determining the type of display to be used. (B) ELECTRO OPTICAL

CHARACTERISTICS OF THE LCD’S The Electro-Optical characteristics of the LCD’s depend

on the type of fluid used. The fluid type determines the contrast ratio, viewing angle and

temperature range of an LCD. The widely used types are Twisted Nematic (TN Standard type) andSuper Twisted Nematic (STN premium high contrast type). TN Fluid TN fluid is the least

expensive type. The viewing angle is about 40-45°,and must be designated “top”’ or “bottom” view

preference. Bottom view is used when the user will be below the plane perpendicular to the display,

such as on a desk calculator. Top view is used when the display is mounted on a vertical surface

below eye level. STN Fluid STN is a high contrast and wide viewing angle fluid. The viewing angle

is about 75° and it can be viewed above and below the plane perpendicular to the display.

Viewing Angle and Direction

The viewing angle can be defined as the cone subtended by the viewers eye, when the Display isviewed at the two extreme angles while having a readable contrast level. The viewing direction can

be defined as the viewers eye direction with respect to the normal drawn perpendicular to the

display’s surface. When the display is viewed from above the normal, it is termed as top view (12O’ Clock). When viewed from below the normal, it is termed as bottom view (6 O’ clock).

Generally, the Displays used are of the bottom view type. A1 – Approximate Nominal viewing cone

(Top & Bottom view) for TN type. B1 – Approximate Adjustable viewing cone (Top & Bottom

view) for TN type. A2 – Approximate Nominal viewing cone for STN type. B2 - Approximate

Adjustable viewing cone for STN type.Brightness Brightness of LCD is a ratio of the luminance





of the reflected or transmitted light to the luminance of the incident light. Reflective display wil

therefore tend to appear rather gray/dark. Brighter display can be obtained by providing

backlighting. Contrast Ratio Contrast Ratio of LCD is a ratio of brightness of the non-activatedpixels to that of the activated pixels. Contrast Ratio = Brightness of Non-activated pixels (B2)

Brightness of activated pixels (B1) B1 B2 SET POINT DRIVING VOLTAGE Brightness &

Contrast, both depend on the polarizers used. Low efficiency polarizers give bright displaysbut low contrast. High efficiency polarizers give high contrast and less brightness.

Illumination Modes In normal version LCD’s, ambient light falls on the display and thereflector present on the backside of the rear glass reflects the light making the charactersreadable. In the backlight version of LCD’s, a light source usually LED array behind the

glass panel provides the light for reading the characters. The TN type LCD, which is usedwidely in the normal / non-backlight version, comes with grey background color. This type is

not generally preferred for the backlighted version. The STN type LCD, which is rapidlyreplacing the older TN type, comes in different types. These are available in grey as well as

green colors. For the backlighted version, these types of LCD’s are preferred. LCD’s

operating in an extended temperature range are also available. Temperature Ranges Normal Temperature Range

LCD

Extended Temperature Range

LCDOperating

Temperature

0 deg C to +50 deg C -20 deg C to +70 deg C

Storage

Temperature

-20 deg C to +70 deg C -30 deg C to +80 deg C

(C) BACKLIGHTING Backlighting is used on LCD’s to make them readable in low light

conditions. Generally, there are two methods to backlight character LCD module: (1) Electroluminescent (EL) and (2) Light Emitting Diode (LED). Selection depends on desired color,

available power and required life. The widely used backlighting is of the LED Array Type. Light

Emitting Diode (LED) LED backlighting offers a significant life advantage over EL lamps, but atthe expense of power and module size. Lamp life is in excess of 50,000 hours, and in most cases, 1

lamp failing does not make the backlight unusable. The absence of any noise/interference, a typical

lifetime of 100,000 hours on an average, the low DC drive voltage of 5V and the various color

options available makes the LED backlighting the widely used one. Standard color is yellow-green,

red, amber and other colors may be special ordered. Since the sensitivity of the eye is maximum at

around 550 nm, the yellow green color backlighting is most widely used. The electro-optical

characteristics of the LED array are given below. There are two types of LED backlights: (1)

Edgelit Style (2) Array Style Edgelit can be used on modules up to 20 characters wide. Beyond 20

characters, the middle of the display begins to dim when compared to the edges. Edgelight type

consumes lesser power compared to array type. Array backlighting produces brighter and moreeven light. Power is the main consideration when designing with this type of from 8 to 40characters per line. module. It is not recommended for battery-powered applications where the

lamp will be on all the time. Variable brightness can be controlled with a digital potentiometer or

pulse-width modulated circuit. (D) PIN DETAILS Pin No. Symbol Descri ption Pin 1 VSS

Ground Terminal, 0V Pin 2 VDD Supply Terminal, +5V Pin 3 VL Liquid Crystal drive voltage Pin

4 RS Register Select: RS = 0 – Instruction Register RS = 1 – Data Register Pin 5 R/W Read /

Write: R/W = 1 – Read R/W = 0 – Write Pin 6 E Enable: Enables Read / Write Pin 7 DB0 Bi-

directional data bus: To to When interface data length is 8 bits, Pin 14 DB7 data transfer is done





CDM 1 2 3 4 5 6 7 8 9 10 11 12 13

once through DB0 - DB7. When the interface data length is 4 bits, data transfer is done twicethrough DB4 – DB7. Pin 15 BACKLIGHT In case of 15 pin modules, Pin15 is the Pin 16 SUPPLY

supply voltage (+5V) for the LED. In case of 16 pin modules, Pin15 is the Ground (0V) and Pin16is the Supply Voltage (+5V) for the LED.

(E) ORDERING INFORMATION

1-5 --- Model Number

1&2 --- Number of Characters 3 --- Number of Lines 4&5 --- Duty Factor 6 --- Model

Identification / Character Size Can be Blank. 7&8 --- Type of LCD TN -- Twisted Nematic STN --Super Twisted Nematic 9&10 --- Background Color GY -- Gray GN -- Green 11&12 ---

Illumination Mode BL -- LED Backlight NL -- Normal 13 --- Temperature Range N -- Normal W -

- Wide NOTE: 1. For some models only 5-digit model number after CDM will reflect on the PCB.

For example CDM 16116. 2. Some Models will have 5-digit + 1 character will reflect on the PCB.

3. The remaining code from 7 to 13 will be on a written sticker. III HARDWARE

DESCRIPTION (A) POWER SUPPLY REQUIREMENTS The supply should be of

+5V at 1 to 10 milliamps. To achieve a better / suitable contrast for the display, the driver voltage(VL) at Pin3 should be adjusted properly. Extended temperature and some high contrast modules

require –5V,also at low current. Inexpensive IC’s convert +5V to –5V efficiently. If the display hasbacklighting, required power must also be budgeted. The power supply does not have to “lock-on”

+5V but it must not “spike” beyond the module’s absolute maximums. A module’s logic circuits

have 3 connections to the power supply: VDD (+5V DC); VSS (Ground); and VL (Contrast or biascontrol or viewing angle adjustment voltage). Recommend the end user to use variable resistor as

shown in the circuit for optimum VLCD (VDD-VL) adjustments to obtain best display contrast and

viewing angle. Power Supply for single supply voltage Power Supply for Dual supply voltageVDD VL VSS

VDD VL VSS

+5VDC +5VDC -5VDC 0VDC 0VDC +5VDC Input LCD Module ±5VDC Input LCD Module

(B) INTERFACING LCD modules can communicate bi-directionally within the master system.

Tie the device into the system data bus & treat it as RAM, I/O, or expanded, parallel I/O. The

module is “selected” by gating a decoded, “module-address” output, with the host processor’s “read

or write” strobe. The resultant signal, applied to the LCD’s “enable” input, clocks in the data. Sincethere is no conventional “chip-select” signal, developing a strobe signal for the Enable signal (E)

and applying appropriate signals to the Register Select (RS) and Read / Write (R/W) signals are

important. Interfacing the module involves: (1) Joining the module to the host’s data bus. (2)

Developing a “strobe” signal for the “E” signal. (3) Applying appropriate signals to module’s “RS”

and “R/W”. (4) Applying the proper “viewing angle” voltage to the display’s VL pin. For 4-bit data interface, the bus lines DB4 to DB7 are used for data transfer, while DB0 to DB3 lines are

disabled. The data transfer is complete when the 4-bit data has been transferred twice. The busy flagmust be checked after the 4-bit data has been transferred twice. For 8-bit data interface, all eight-





bus lines (DB0 to DB7) are used. INTERFACING TO MCU 4-BIT DATA INTERFACE

P1.0 P1.1 MCU P1.2 P3.4 P3.5 P3.6 P3.7

E RS R/W LCD MODULE DB4 DB5 DB6 DB7

8 BIT DATA INTERFACE

E RS R/W LCD MODULE DB0 TO DB7

P1.0 MCU P1.1 P1.2 P3.0 TO P3.7

(C) TIMING ASPECTS OF LCD’S LCD modules must be properly interfaced to the host microcontroller. The modules are classified as a “slow” peripheral. Both access and strobe times exceed

those normally encountered. The Enable (E) signal is the key signal line. The E signal must be a positive going digital strobe, which is active while data and control information are stable and true.The falling edge of the E signal enables the data/instruction register of the controller. All module

timings are referenced to specific edges of the E signal. The E signal is applied only when a

specific module transaction is desired. The Read and Write strobes of the host, which provides the

E signal, should not be linked to the module’s R/W line. An address bit, which sets up earlier in the

host’s Machine Cycle, can be used as R/W. The problem is encountered when the host processor is

running so fast that the strobes are two narrow to serve as the E pulse. In this case: § Prolong these

pulses by using the host’s ‘Ready’ input. § Prolong the host by adding wait states. § Decrease the

host’s crystal frequency. When these options are not viable it will be necessary to latch both data

and control information and then activate the E signal. The module presents no difficulties whileinterfacing slower MCU’s.

The Relationship between the operation and the combination of RS, R/W

RS R/W E OPERATION0 0 Write instruction

code

0 1 Read busy flag and

Address Counter1 0 Write data

1 1 Read data

The Interface timing diagrams and the Read / Write timing diagrams are given below IV

SOFTWARE DESCRIPTION (A) INTRODUCTION Software determines what, how, and where

data is displayed on the LCD. The special features of the built in LCD controller IC are: ¨

Character Generator ROM (CG ROM) that provides 208 characters with font 5x8 dots and 32

characters with font 5x10 dots ¨ Character Generator RAM (CG RAM) having a storage function of

8 character patterns, which can freely be changed by users program ¨ Display Data RAM with a maximum of 80 characters ¨ Bi-directional 8 or 4 bit data bus interface ¨ Automatic reset on





RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0

RS R/W X X X X X X X X


R/W -- Read / Write

R/W -- 1: Data is read from CG RAM / DD RAM

R/W -- 0: Data is written to CG RAM / DD RAMRS -- Register Select

RS -- 0: Selects Command Register for Reading / Writing

RS -- 1: Selects Data Register for Reading / writing


0 0 0 0 0 0 0 0 0 1

power up ¨ Internal oscillator with an external resistor (No external clock required) ¨ Wide rangeof instruction functions including: Display clear, Cursor Positioning, Display or Cursor shift on

data entry and Display ON/OFF. Display Data RAM (DD RAM): The character to be displayed iswritten into the DD RAM, in the form of 8 bit character codes present in the character font table.

DD RAM can store a maximum of 80 characters. The display data RAM (DD RAM) that is not used

for display can be used as general data RAM. Depending on the 8-bit character code that is writtenin to the DD RAM, LCD will select the character pattern either from Character Generator RAM

(CG RAM) or from Character Generator ROM (CG ROM). Character Generator ROM (CGROM): The CG ROM generates 5x8 dot or 5x10 dot character patterns from 8 bit character codes

(refer character font table). It can generate 208, 5x8 dot character patterns and 32, 5x10 dot

character patterns. When an 8-bit character code of the CG ROM is written to the DD RAM, the

character pattern of the CG ROM corresponding to the code is displayed on the LCD display

position corresponding to the DD RAM. Character Generator RAM (CG RAM): In the CG

RAM, the user can rewrite character patterns by program. For 5x8 dots, 8 character patterns can be

written and for 5x10 dots, 4 characters patterns can be written. Programming of these character

patterns is explained in CG RAM programming. (B) INSTRUCTION CODES Instruction codes

are the control information sent by the user, through the micro controller, to the IR and DR of the

controller IC, present in the module. Before starting the internal operation, the controller storesthe control information temporarily in these registers. The internal operations are determined by

the signals sent from the MCU, which include RS, R/W, E signal and the Data Bus (DB0-DB7).

NOTE

DATA For Instruction Register / Data register

§ CLEAR DISPLAY

Loads character code for blank (20H) into all the DD RAM addresses. The cursor returns to

address 0(Address = “80”) and display, if it has been shifted, returns to the original position. i.e.,

display disappears and the cursor goes to the left edge of the display (to the first line if 2/4 linedisplay module is used). The Cursor is brought to the first position of first line. Instruction

execution time is 1.52ms.

DB7 – DB0 -- 01H: Clears the Display and all the DD RAM locations

§ RETURN HOME





0 0 0 0 0 0 0 0 1 X


0 0 0 0 0 0 0 1 I/D S


0 0 0 0 0 0 1 D C B


0 0 0 0 0 1 S/C R/L X X


0 0 0 0 1 DL N F X X

DB7 – DB0 -- 02H , 03H: The cursor goes to the first position of the first line Returns the cursor

to address 0(Address=80) and display, if it has been shifted, to the original position. The DD RAM

contents remain unchanged. Instruction execution time is 1.52ms. § ENTRY MODE SET

I/D = 0: Decrements the address of DD RAM / CG RAM when data is written to or read from DD

RAM / CG RAM. Cursor is shifted left on the display. I/D = 1: Increments the address DD RAM / CG RAM when data is written to or read from DD RAM / CG RAM. Cursor is shifted right on the

display. S = 0: The Display is not scrolled. S = 1: The display scrolls. Direction of scrolls dependson the value of I/D. DATA DB7 – DB0 -- 04H: Data written from right to left. Display is not

scrolled. DB7 – DB0 -- 06H: Data written from left to right. Display is not scrolled. DB7 – DB0 -

- 05H: Data written from right to left. Display scrolls. DB7 – DB0 -- 07H: Data written from left

to right. Display scrolls. Instruction execution time is 37µS. § DISPLAY ON / OFF

D: The display is ON when D=1, and OFF when D=0. When OFF, the display data remains in theDD RAM and can be displayed by setting D to 1. C: The cursor is displayed when C=1, and not

displayed when C=0. The cursor is displayed in the 8th line for the character font selection of 5x8dots. B: The character indicated by the cursor blinks when B=1. The blinking is displayed as

switching between all black dots (dots ON) and displayed character at a speed of 409.6ms intervals

while the controller IC operates at a clock frequency of 250KHZ. DATA DB7 – DB0 -- 08H

Display OFF DB7 – DB0 -- 0CH Display ON and cursor OFF DB7 – DB0 -- 0EH Display ON and

cursor ON not Blinking DB7 – DB0 -- 0FH Display ON and cursor ON Blinking Instruction

execution time is 37µS. § CURSOR / DISPLAY SHIFT This instruction shifts the cursor / display

to the right or left, without writing or reading the display data. This function is used for correction

or search of display.

S/C R/L 0 0 Shifts the cursor position to the left. AC is decremented by one. 0 1 Shifts the cursorposition to the right. AC is incremented by one. 1 0 Shifts the entire Display to the left. Cursor

follows the display shift. 1 1 Shifts the entire Display to the right. Cursor follows the display shift.

When the displayed data is shifted repeatedly, each line moves horizontally. The second linedisplay does not shift in to the first line position. The Address Counter contents would not change,

if only, the display shift operation is performed. Instruction execution time is 37µS. DATA DB7 –

DB0 -- 10H: Shifts the cursor position to left DB7 – DB0 -- 14H: Shifts the cursor position toright DB7 – DB0 -- 18H: Shifts the entire display to left Cursor follows the display shift DB7 – DB0 -- 1CH: Shifts the entire display to right Cursor follows the display shift § FUNCTION SET

This instruction initializes the system, and must be the first instruction to be executed after power

on. Instruction execution time is 37µS.

DLSets the interface data length to 8-bit when DL=1, and 4-bit when DL=0. N – Sets the

Number of Display lines F – Sets the Character fontDATA DB7 – DB0 -- 30H: Sets the display as

One Line, 5 X 8 dots character size and data transfer is 8-Bits DB7 – DB0 -- 34H: Sets the display






0 0 0 1 ACG ACG ACG ACG ACG ACG


0 0 1 ADR ADR ADR ADR ADR ADR ADR


1 0 DATA DATA DATA DATA DATA DATA DATA DATA




as One Line, 5 X 10 dots character size and data transfer is 8-Bits DB7 – DB0 -- 38H: Sets thedisplay as Two Lines, 5 X 8 dots character size and data transfer is 8-Bits DB7 – DB0 -- 20H: Sets

the display as One Line, 5 X 8 dots character size and data transfer is 4-Bits DB7 – DB0 -- 24H:

Sets the display as One Line, 5 X 10 dots character size and data transfer is 4-Bits DB7 – DB0 --28H: Sets the display as Two Lines, 5 X 8 dots character size and data transfer is 4-Bits Note: This

instruction also sets the display as four lines, 5 X 8 dots character in 4-line display modules. § SETCG RAM ADDRESS This instruction loads a new 6-bit address into the Address Counter and sets it

to address the CG RAM. Henceforth, the contents of the Address Counter will be automaticallymodified after each access of CG RAM, as selected by the ‘Entry Mode set’ instruction. If this

instruction is issued by the system MCU while the display is enabled, and if either the cursor or

blink is on, the display will blink. To avoid this, both the cursor and display blink should be turned

off before loading a new CG RAM address. Instruction execution time is 37µS.

DB7 – DB0 -- 40H to 7EH § SET DD RAM ADDRESS This instruction loads a new 7-bit addressinto the Address Counter and sets it to address the DD RAM. Data is then written to or read from

the MCU for DD RAM. Henceforth, the contents of the Address Counter will be automatically

modified after each access of DD RAM, as selected by the ‘Entry Mode set’ instruction.

Instruction execution time is 37µS.

DB7 – DB0 -- 80H to CFH for one line display DB7 – DB0 -- 80H to A7H for line one of two-linedisplay DB7 – DB0 -- C0H to E7H for line two of two-line display § DD RAM / CG RAM DATA

WRITE This instruction writes the data in DB7 to DB0 into either the CG RAM/ DD RAM,depending on the last executed ‘Set CG RAM address’ or ‘Set DD RAM address’ instruction, and

the parameters of the instruction. Henceforth, the contents of the Address Counter will be

automatically modified as per the ‘Entry Mode set’ instruction, after each data write operation.Instruction execution time is 37µS.

. DB7 to DB0 Data to be written § DD RAM / CG RAM DATA READ The instruction reads data DB7 to DB0 from CG RAM / DD RAM depending on the type of ‘Set RAM address’ instruction

last executed. Prior to inputting this read instruction, either the CG RAM address set instruction orthe DD RAM address set instruction must be executed. If it is not done, the first read data becomes

invalid, and data of the next address is read normally from the second read. Henceforth, the

contents of the Address Counter will be automatically modified as per the ‘Entry Mode set’instruction, after each data read operation. Instruction execution time is 37µS.

DB7 to DB0 Data to be read § READ BUSY FLAG (BF) / ADDRESS COUNTER This instructiongives the current value of the Address Counter and the busy flag status. BF set to 1 indicates that

the internal operation is in progress, and the next instruction will be accepted only after BF is reset

to 0. The next seven bits point to a location, either in CG RAM or DD RAM depending on the ‘SetRAM address’ instruction last executed. Instruction execution time is 1µS.





0 1 BF AC AC AC AC AC AC AC

BF – BUSY FLAG: AC – ADDRESS COUNTER VALUE DB6 to DB0 gives the address NOTE:

Instruction execution time changes when frequency changes. (C) INITIALIZATION FLOW FOR

8 BIT AND 4 BIT LCD MODULES

Power ON

Power ON

Wait for 15 millisecond or more After VDD rises to 4.5V

Wait for 15 millisecond or more After VDD rises to 4.5V

RS R/W DB7 DB6 DB5 DB4 (Set interface length 8 bit) 0 0 0 0 1 1

Set interface length 8 bit RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 1 1 X X X X

Wait for more than 4.1 µS



Wait for more than 100 µS



Wait for more than 100 µSCheck for busy flag or give a time delay of 2ms



Check for busy flag or give a time delay of 2msSet interface length 8 bit RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 1 1 N F X X

Check for busy flag or give a time delay of 2msSet Display OFF RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 1 0 0 0

Check for busy flag or give a time delay of 2ms

Set Display Clear RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 0 0 0 1

Check for busy flag or give a time delay of 2msCheck for busy flag or give a time delay of 2ms

RS R/W DB7 DB6 DB5 DB4 (Set interface length 4 bit) 0 0 0 0 1 0 0 0 N F X X

RS R/W DB7 DB6 DB5 DB4 (Set Display OFF) 0 0 0 0 0 0 0 0 1 0 0 0


RS R/W DB7 DB6 DB5 DB4 (Set Display Clear) 0 0 0 0 0 0 0 0 0 0 0 1






RS R/W DB7 DB6 DB5 DB4 (Set Entry Mode) 0 0 0 0 0 0 0 0 0 1 I/D SCheck for busy flag or give a time delay of 2ms

RS R/W DB7 DB6 DB5 DB4 (Set Display Clear & cursor 0 0 0 0 0 0 returns to home position) 00 0 0 0 1 End of Initialization


Set Entry Mode RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 0 1 I/D SCheck for busy flag or give a time delay of 2ms

RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 0 0 0 1 SetDisplay Clear & cursorreturns to home position. End of initialization

INITIALIZATION BY INTERNAL RESET CIRCUIT 4.5V

0.2V VDD 0.2V 0.2V TOFF

TRON 0.1 ms ≤ TRON ≤ 10ms TOFF ≥ 1ms POWER SUPPLY RESTRICTION TRON – Power

Supply Rise Time TOFF – Power Supply OFF Time If the electrical characteristics of the power

supply meet the above specification, the internal reset circuit automatically initializes thecontroller IC when the power is turned on. The busy flag is kept in the busy state (BF = 1) until the

initialization ends. The busy state lasts for 15ms after VDD rises to 4.5V. The followinginstructions are executed by default, during the internal initialization routine: § Display Clear §

Function Set: DL = 1 ; 8 Bit Data Interface N = 0 ; 1 Line Display F = 0 ; 5x8 Dot Character Font §Display on/off control: D = 0 ; Display off C = 0 ; Cursor off B = 0 ; Blinking off § Entry Mode

Set: I/D = 1 ; Increment by one S = 0 ; No Shift § DD RAM is selected After power on, if theDisplay is not initialized automatically, initialization by instruction should be carried out. (D)

FUNCTIONAL DESCRIPTION OF THE CONTROLLER IC Registers: The controller IC has

two 8-bit registers, an Instruction Register (IR) and a Data Register (DR). The IR stores theinstruction codes and address information for DD RAM and CG RAM. The IR can be written, but

not read by the Micro Controller Unit (MCU). The DR temporarily stores the data to be written to /

read from the DD RAM or CG RAM. The data written to DR by the MCU is automatically written

to the DD RAM or CG RAM as an internal operation. When an address code is written to IR, the

data (of the specified address) is automatically transferred from the DD RAM or CG RAM to the

DR. Data transfer between the MCU is then completed when the MCU reads the DR. Likewise, for

the next MCU read of the DR, data in DD RAM or CG RAM at the next address is sent to the DR

automatically. Similarly, for the MCU write of the DR, the next DD RAM or CG RAM address is

selected for the write operation. The Register Selection table is as shown below: RS R/W

Operation 0 0 IR write as an internal operation 0 1 Read Busy Flag (DB7) and Address Counter(DB0 to DB6) 1 0 DR write as an internal operation (DR to DD RAM or CG RAM) 1 1 DR read asan internal operation (DD RAM or CG RAM to DR) Busy Flag: When the busy flag is 1, the

controller is in the internal operation mode and the next instruction will not be accepted. When RS= 0 and R/W = 1, the busy flag is output from DB7. The next instruction must be written after

ensuring that the busy flag is 0. Address Counter: The Address Counter allocates the address for

the DD RAM and CG RAM Read/Write operation. When the instruction code for a DD RAMaddress or CG RAM address setting, is input to the IR, the address code is transferred from IR to

the Address Counter. After writing/reading the display data to/from the DD RAM or CG RAM, the

Address Counter increments/decrements the address by one, as an internal operation. The data of





80 81 82 83 84 85 86 8780 81 82 83 84 85 86 87C0 C1 C2 C3 C4 C5 C6 C7

80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F

C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF

80 81 82 83 84 85 86 87 --- --- --- 8F 90 91 92 93C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- CF D0 D1 D2 D3

80 81 82 83 84 85 86 87 --- --- --- 8F 90 91 92 93

C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- CF D0 D1 D2 D3

94 95 96 97 98 99 9A 9B --- --- --- A3 A4 A5 A6 A7D4 D5 D6 D7 D8 D9 DA DB --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87 --- --- --- A3 A4 A5 A6 A7

C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87 --- --- --- A3 A4 A5 A6 A7

C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87 --- --- --- A3 A4 A5 A6 A7

the Address Counter is output to DB0 to DB6 while R/W = 1 and RS = 0. (E) DD RAM

LOCATIONS The DD RAM is used to store display data of 8 bit character codes present in the

Character Font Table. The DD RAM address corresponds to specific display position on the LCD.

The DD RAM address should be set in the Address Counter, so as to enable the display of characters on the LCD. DD RAM address is set in the Address Counter (AC) as a hexadecimal

number. MSB DD RAM Address LSB1 AC6 AC5 AC4 AC3 AC2 AC1 AC0

Note: The DD RAM address is a 7-bit address; the 1 in the MSB is for the controller to identify theDD RAM address (Ref set DD RAM address instruction in the IV (B) instruction codes)DD RAM

can store a maximum of 80 characters, 01 02 03 04 05 … 78 79 80 80 81 82 83 84 … CD CE CF

(DD RAM Address)

DD RAM ADDRESSES FOR THE DIFFERENT

CRYSTALONICS DISPLAY MODULES:

1 l ine x 8 characters Display Mode 2 line x 8 characters Display Mode

LINE1 LINE1 LINE2

1 l ine x 16 characters Display Mode (For CDM

16116 Module) 80 81 82 83 84 85 86 87 C0 C1 C2 C3 C4 C5 C6 C7

2 l ine x 16 characters Display Mode LINE

1

LINE 2

2 l ine x 20 characters Display Mode

LINE1

LINE 2

4 l ine x 20 characters Display Mode LINE

1

LINE2

LINE 3 LINE 4


80 81 82 83 84 85 86 87 88 --- --- 9B 9C 9D 9E 9F2 l ine x 40 characters Display Mode

LINE

1LINE 2


LINE

1

LINE







0 0 0 0 * 0 1 0 0 1 0 0 0 0 0 1 0 0 0 1 * * * 1 0 0 0 1 * * * 1 1 0

1 10 0 0 0 * 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1

1 1 1 1 1

* * * 0 0 1 0 0 * * * 0 1 0 1

0 * * * 1 1 0 1 1

Don’t CareNotes: §

Character code

bits 0-2correspond to CG RAM address bits 3-5 for a total of 8 patterns. § CG RAM address codes 0-2

designate character pattern line. The 8th line is the cursor position. It is logically ‘OR’ed with thecursor instruction. § Character patterns are loaded in to CG RAM data bits 0-4 as shown in the

table. Since CG RAM bits 5-7 are not used, they may be used for general data RAM. § CG RAMpatterns are displayed on the LCD when character code bits 4-7 are all “0”. Bit 3 is a don’t care bit.

Therefore, character pattern (1) can be selected with character code 00H or 08H. § “1” in the

character pattern turns a dot “ON”. “0” indicates a non-selected dot. Flow of CG RAM

programming:

Set DD RAM Data

Set DD RAM Address

Set CG RAM AddressSet CG RAM Data

Initialize the LCD

(G) CHARACTER FONT TABLE

V PRECAUTIONS (A) POWER SUPPLY PRECAUTIONS § Always check the

absolute maximum rating of the LCD driver. § The polarity of the supply voltage should not be

reversed. § Use a clean power source free from transients. § The ground terminal of the power

supply must be isolated properly so that no voltage is induced in it. § The module should be

isolated from the other circuits, so that stray voltages are not induced, which could cause a

flickering display. § The +5V power for the module should also supply the power to all devices,

which may access the display. Don’t allow the data bus to be driven when the logic supply isdisabled. § VDD must, at all times, exceed the VL voltage level. Do not install a capacitor between

the VL pin and ground. The capacitor combines with the contrast potentiometer to form an R-Cnetwork, which “holds-up” VL, at the power-down, damaging the module. (B) MECHANICAL

PRECAUTIONS § Cover the display surface with a transparent protective plate, to protect the

polarizer. § Mount the module so that it is free from torque and physical loads. § Do not useorganic solvents to clean the display panel as these may adversely affect the polarizers. Dust may

be removed by adhesive tape or with absorbent cotton and petroleum benzene. § Ensure that thesoldering is proper, as dry soldering causes improper character display. § The processing or even a

slight deformation of the claws of the metal frame will have effect on the connection of the outputsignal and cause an abnormal display. § Do not damage or modify the pattern writing, or drill

attachment holes in the PCB. When assembling the module into another equipment, the space

between the module and the fitting plate should have enough height, to avoid causing stress to the

module surface. § Make sure that there is enough space behind the module, to dissipate the heat

generated by the IC’s while functioning for longer durations. § Employ anti-static procedures while

handling the module. (C) ENVIRONMENTAL PRECAUTIONS § Prevent moisture build-up on

the module. § Contact with water or oil over a long period of time may cause deformation or colorfading of the display. Condensation on the terminals can cause electro-chemical reaction disrupting

the terminal circuit. § Operate the LCD module under the relative condition of 40ºC and 50%





relative humidity. Lower temperature can cause retardation of the blinking speed of the display,while higher temperatures make the overall display discolor. Polarization degradation, bubble

generation or polarizer peel off may occur with high temperature and humidity. § Do not store indirect sunlight. (D) OPERATING PRECAUTIONS § A module should not be inserted or

removed from a live circuit. § Minimize the cable length between the module and the host. Long

lengths may introduce noise or damaging voltages due to antenna-effect. § Don’t touch the displaysurface with bare hands or any hard materials. This will stain the display area and degrade the

insulation between terminals. VI TROUBLESHOOTING q No Data is displayed § Check if thepower supplied (VDD, VL, VSS) is as per the Data sheet specification. § Check the Interface

connections. Ensure that there are no I/O pads bridged. § Check the supply current. Ensure IC’s and

resistors are not heated. Immediately turn off the power before checking the connection, if it is

heated. q Improper initialization § Check if the initialization routine is as per the Data Sheet. § See

if the system is operated without making a BUSY FLAG check. If so, make a BUSY FLAG Check. §

Check if the interface pins (RS, R/W, E and DB0-DB7) are connected properly or not. § Check the

signal timings. Check that all setup times are followed. q Improper Character Display § When the

characters to be displayed are missing in between, the data read/write is too fast. A slower

interfacing frequency would rectify the problem. § If a character not found in the font table is

displayed, or a character is missing, the CG ROM is faulty and the controller IC has to be changed.§ In a multi line display, if the display of characters in the subsequent lines doesn’t take place

properly; send proper DD RAM Addresses in the initialization code. § The display ON / OFF flag isturned OFF by the internal initialization routine. This flag has to be explicitly turned ON and it is

always better to send an initialization routine after power up. § If particular pixels of the charactersare missing, or not getting activated properly, there could be an assembling problem in the module.

q Data cannot be read § Check if the connections and polarity of RS and R/W are as per the manualspecification. § Check if there is a contention between any peripheral equipment and the data bus.

§ Check the signal timings. Check that all setup times are followed. § See if the system is operated

without making a BUSY FLAG check. If so, make a BUSY FLAG Check. § Check for errors in thesoftware. q In case any other problems are encountered, you could send the module to our factory

for testing and evaluation.

CRYSTALONICS DISPLAYS Bright Future

CONTACT INFORMATION: CRYSTALONICS DISPLAYS (P) LTD Plot No. 38, SIPCOT

Industrial Complex, Phase II, Kumudepalli Post, Hosur - 635 109, Tamil Nadu. Telephone: 04344-

260389 / 260199 Telefax: 260391. E-Mail id: CDM - USER’S

MANUAL CONTENTS

I FEATURES OF CRYSTALONICS

DISPLAY MODULES II GENERAL VIEW OF AN LCD (A) INTRODUCTION (B) ELECTRO

OPTICAL CHARACTERISTICS OF THE LCD’S (C) BACKLIGHTING (D) PIN DETAILS (E)ORDERING INFORMATION III HARDWARE DESCRIPTION (A) POWER SUPPLY

REQUIREMENTS (B) INTERFACING (C) TIMING ASPECTS OF LCD’S IV SOFTWAREDESCRIPTION (A) INTRODUCTION (B) INSTRUCTION CODES (C) INITIALIZATION FLOW

FOR 8 BIT AND 4 BIT LCD MODULES (D) FUNCTIONAL DESCRIPTION OF THE

CONTROLLER IC (E) DDRAM LOCATIONS (F) CGRAM PROGRAMMING (G) CHARACTER

FONT TABLE V PRECAUTIONS (A) POWER SUPPLY PRECAUTIONS (B) MECHANICAL





PRECAUTIONS (C) ENVIRONMENTAL PRECAUTIONS (D) OPERATING PRECAUTIONS VITROUBLESHOOTING

I FEATURES OF CRYSTALONICS DISPLAY MODULES q Displays Alphanumeric

Characters, Special symbols & characters q Easy interface with a 4-bit or 8-bit MCU q Built-in Dot

Matrix LCD Controller with font 5x8 or 5x10 Dots q Built in Display Data RAM (DD RAM),

Character Generator RAM (CG RAM) and Character Generator ROM (CG ROM) q Automatic

power on Reset q Low power consumption q Various instruction functions q High contrast ratio q

Wide viewing angle q Rapid response time q With & without Backlight q High quality standards q

Long life q Custom made LCD’s q Wide temperature range * q C-Dot Approved * * Applies forselected Modules only. II GENERAL VIEW OF AN LCD (A) INTRODUCTION The Liquid

Crystal Display (LCD) is a thin layer of ”Liquid Crystal Material” deposited between two plates of

glass. LCD’s have materials, which combine the properties of both Liquids and Crystals. Rather

than having a melting point, they have a temperature range with in which the molecules are almost

as mobile as they would be in a Liquid, but are grouped together in an ordered form similar to a Crystal. An LCD consists of two glass panels, with the liquid crystal material sandwiched in

between them. The inner surfaces of the glass plates are coated with transparent electrodes, whichdefine the character, symbols or patterns to be displayed. Polymeric layers are present in between

the electrodes and the liquid crystal, which makes the liquid crystal molecules to maintain a

defined orientation angle. There are polarizers on the glass panels. These polarizers rotate the light

rays passing through them to a definite angle in a particular direction. When LCD is in the off state

light rays are rotated by the two polarizers and the liquid crystal, such that the light rays come outof the LCD without any orientation, and the LCD appears transparent. When sufficient voltage is

applied to the electrodes, the liquid crystal molecules would be aligned in a specific direction. The

light rays, which are rotated by polarizers passing through the LCD, would result in highlighting the

specific character. Since LCD’s consume less power they are compatible with low power

electronic circuits, and can be powered for long durations. The LCD’s have a long life and wideoperating temperature range between -20°C and +70°C. The LCD’s are lightweight with only a few

millimeters thickness. LCD’s do not generate light. So light is required to read the display. HenceDisplays are readable both day and night by selecting a backlight option. LCD’s are extensively

used in segment displays like Watches, Calculators, Clock, Camera, Audio Equipments, HomeAppliances, Instruments, Telephones, Automobiles, and Games etc. Recent advances in LCD

technologies have resulted in LCD’s being extensively used in telecommunications and consumerelectronics. The LCD’s have even started replacing Cathode Ray Tubes (CRTs) used for the display

of text and graphics, and also in TV applications. An LCD module is selected depending on § The

size and format required in displaying the desired information. § The optical characteristics thatlooks best in the module. Alphanumeric modules display characters, numerals, symbols and some

limited graphics. Interface is achieved via a bi-directional, parallel ASCII data bus. Necessary

features such as Character generation RAM (CG RAM), Display Device RAM (DDRAM)

addressing, cursor scrolling, Blanking, User programmable fonts and Handshake are all included.

These modules are the simplest and most economic means to communicate between any micro

system and the outside world. Alphanumeric modules ranges One, two or four character lines are

possible. Most formats are available in a variety of packages to meet various mounting

requirements. Selecting the exact version of an LCD once the format is decided is largely a

subjective judgment. Color, fluid type and backlighting determine the overall look of the display





and often the appearance of the final product. Operating condition such as temperature, lightingcondition and available power are also factors in determining the type of display to be used. (B)

ELECTRO OPTICAL CHARACTERISTICS OF THE LCD’S The Electro-Opticalcharacteristics of the LCD’s depend on the type of fluid used. The fluid type determines the

contrast ratio, viewing angle and temperature range of an LCD. The widely used types are Twisted

Nematic (TN Standard type) and Super Twisted Nematic (STN premium high contrast type). TN

Fluid TN fluid is the least expensive type. The viewing angle is about 40-45°,and must be

designated “top”’ or “bottom” view preference. Bottom view is used when the user will be belowthe plane perpendicular to the display, such as on a desk calculator. Top view is used when the

display is mounted on a vertical surface below eye level. STN Fluid STN is a high contrast and

wide viewing angle fluid. The viewing angle is about 75° and it can be viewed above and below the

plane perpendicular to the display.

Viewing Angle and Direction

The viewing angle can be defined as the cone subtended by the viewers eye, when the Display isviewed at the two extreme angles while having a readable contrast level. The viewing direction can

be defined as the viewers eye direction with respect to the normal drawn perpendicular to thedisplay’s surface. When the display is viewed from above the normal, it is termed as top view (12O’ Clock). When viewed from below the normal, it is termed as bottom view (6 O’ clock).

Generally, the Displays used are of the bottom view type. A1 – Approximate Nominal viewing cone

(Top & Bottom view) for TN type. B1 – Approximate Adjustable viewing cone (Top & Bottom

view) for TN type. A2 – Approximate Nominal viewing cone for STN type. B2 - Approximate

Adjustable viewing cone for STN type.Brightness Brightness of LCD is a ratio of the luminance of

the reflected or transmitted light to the luminance of the incident light. Reflective display will

therefore tend to appear rather gray/dark. Brighter display can be obtained by providing

backlighting. Contrast Ratio Contrast Ratio of LCD is a ratio of brightness of the non-activatedpixels to that of the activated pixels. Contrast Ratio = Brightness of Non-activated pixels (B2)Brightness of activated pixels (B1) B1 B2 SET POINT DRIVING VOLTAGE Brightness &

Contrast, both depend on the polarizers used. Low efficiency polarizers give bright displays but lowcontrast. High efficiency polarizers give high contrast and less brightness. Illumination Modes In

normal version LCD’s, ambient light falls on the display and the reflector present on the backside

of the rear glass reflects the light making the characters readable. In the backlight version of LCD’s, a light source usually LED array behind the glass panel provides the light for reading the

characters. The TN type LCD, which is used widely in the normal / non-backlight version, comeswith grey background color. This type is not generally preferred for the backlighted version. The

STN type LCD, which is rapidly replacing the older TN type, comes in different types. These areavailable in grey as well as green colors. For the backlighted version, these types of LCD’s are

preferred. LCD’s operating in an extended temperature range are also available. Temperature

Ranges

Normal Temperature Range LCDExtended Temperature Range LCD

Operating

Temperature

0 deg C to +50 deg C -20 deg C to +70 deg C

Storage Temperature -20 deg C to +70 deg C -30 deg C to +80 deg C

(C) BACKLIGHTING Backlighting is used on LCD’s to make them readable in low light





CDM 1 2 3 4 5 6 7 8 9 10 11 12 13

conditions. Generally, there are two methods to backlight character LCD module: (1) Electroluminescent (EL) and (2) Light Emitting Diode (LED). Selection depends on desired color,

available power and required life. The widely used backlighting is of the LED Array Type. Light

Emitting Diode (LED) LED backlighting offers a significant life advantage over EL lamps, but at

the expense of power and module size. Lamp life is in excess of 50,000 hours, and in most cases, 1

lamp failing does not make the backlight unusable. The absence of any noise/interference, a typicallifetime of 100,000 hours on an average, the low DC drive voltage of 5V and the various color

options available makes the LED backlighting the widely used one. Standard color is yellow-green,red, amber and other colors may be special ordered. Since the sensitivity of the eye is maximum at

around 550 nm, the yellow green color backlighting is most widely used. The electro-optical

characteristics of the LED array are given below. There are two types of LED backlights: (1)

Edgelit Style (2) Array Style Edgelit can be used on modules up to 20 characters wide. Beyond 20

characters, the middle of the display begins to dim when compared to the edges. Edgelight type

consumes lesser power compared to array type. Array backlighting produces brighter and more

even light. Power is the main consideration when designing with this type of from 8 to 40

characters per line. module. It is not recommended for battery-powered applications where the

lamp will be on all the time. Variable brightness can be controlled with a digital potentiometer or

pulse-width modulated circuit. (D) PIN DETAILS Pin No. Symbol Description Pin 1 VSSGround Terminal, 0V Pin 2 VDD Supply Terminal, +5V Pin 3 VL Liquid Crystal drive voltage Pin 4

RS Register Select: RS = 0 – Instruction Register RS = 1 – Data Register Pin 5 R/W Read / Write:

R/W = 1 – Read R/W = 0 – Write Pin 6 E Enable: Enables Read / Write Pin 7 DB0 Bi-directionaldata bus: To to When interface data length is 8 bits, Pin 14 DB7 data transfer is done once through

DB0 - DB7. When the interface data length is 4 bits, data transfer is done twice through DB4 – DB7. Pin 15 BACKLIGHT In case of 15 pin modules, Pin15 is the Pin 16 SUPPLY supply voltage

(+5V) for the LED. In case of 16 pin modules, Pin15 is the Ground (0V) and Pin16 is the Supply

Voltage (+5V) for the LED.

(E) ORDERING INFORMATION

1-5 --- Model Number

1&2 --- Number of Characters 3 --- Number of Lines 4&5 --- Duty Factor 6 --- ModelIdentification / Character Size Can be Blank. 7&8 --- Type of LCD TN -- Twisted Nematic STN --

Super Twisted Nematic 9&10 --- Background Color GY -- Gray GN -- Green 11&12 ---Illumination Mode BL -- LED Backlight NL -- Normal 13 --- Temperature Range N -- Normal W --

Wide NOTE: 1. For some models only 5-digit model number after CDM will reflect on the PCB.

For example CDM 16116. 2. Some Models will have 5-digit + 1 character will reflect on the PCB.

3. The remaining code from 7 to 13 will be on a written sticker. III HARDWARE

DESCRIPTION (A) POWER SUPPLY REQUIREMENTS The supply should be of

+5V at 1 to 10 milliamps. To achieve a better / suitable contrast for the display, the driver voltage

(VL) at Pin3 should be adjusted properly. Extended temperature and some high contrast modulesrequire –5V,also at low current. Inexpensive IC’s convert +5V to –5V efficiently. If the display has

backlighting, required power must also be budgeted. The power supply does not have to “lock-on”

+5V but it must not “spike” beyond the module’s absolute maximums. A module’s logic circuits

have 3 connections to the power supply: VDD (+5V DC); VSS (Ground); and VL (Contrast or bias





control or viewing angle adjustment voltage). Recommend the end user to use variable resistor asshown in the circuit for optimum VLCD (VDD-VL) adjustments to obtain best display contrast and

viewing angle. Power Supply for si ngle supply voltage Power Supply for Dual supply voltage

VDD VL VSS

VDD VL VSS

+5VDC +5VDC -5VDC 0VDC 0VDC +5VDC Input LCD Module ±5VDC Input LCD Module

(B) INTERFACING LCD modules can communicate bi-directionally within the master system.

Tie the device into the system data bus & treat it as RAM, I/O, or expanded, parallel I/O. Themodule is “selected” by gating a decoded, “module-address” output, with the host processor’s “read

or write” strobe. The resultant signal, applied to the LCD’s “enable” input, clocks in the data. Since

there is no conventional “chip-select” signal, developing a strobe signal for the Enable signal (E)

and applying appropriate signals to the Register Select (RS) and Read / Write (R/W) signals are

important. Interfacing the module involves: (1) Joining the module to the host’s data bus. (2)

Developing a “strobe” signal for the “E” signal. (3) Applying appropriate signals to module’s “RS”

and “R/W”. (4) Applying the proper “viewing angle” voltage to the display’s VL pin. For 4-bit data

interface, the bus lines DB4 to DB7 are used for data transfer, while DB0 to DB3 lines aredisabled. The data transfer is complete when the 4-bit data has been transferred twice. The busy flagmust be checked after the 4-bit data has been transferred twice. For 8-bit data interface, all eight-

bus lines (DB0 to DB7) are used. INTERFACING TO MCU 4-BIT DATA INTERFACE

P1.0 P1.1 MCU P1.2 P3.4 P3.5 P3.6 P3.7

E RS R/W LCD MODULE DB4 DB5 DB6 DB7

8 BIT DATA INTERFACE

E RS R/W LCD MODULE DB0 TO DB7P1.0 MCU P1.1 P1.2 P3.0 TO P3.7

(C) TIMING ASPECTS OF LCD’S LCD modules must be properly interfaced to the host microcontroller. The modules are classified as a “slow” peripheral. Both access and strobe times exceed

those normally encountered. The Enable (E) signal is the key signal line. The E signal must be a positive going digital strobe, which is active while data and control information are stable and true.

The falling edge of the E signal enables the data/instruction register of the controller. All module

timings are referenced to specific edges of the E signal. The E signal is applied only when a specific module transaction is desired. The Read and Write strobes of the host, which provides the

E signal, should not be linked to the module’s R/W line. An address bit, which sets up earlier in the

host’s Machine Cycle, can be used as R/W. The problem is encountered when the host processor is

running so fast that the strobes are two narrow to serve as the E pulse. In this case: § Prolong these

pulses by using the host’s ‘Ready’ input. § Prolong the host by adding wait states. § Decrease the

host’s crystal frequency. When these options are not viable it will be necessary to latch both data

and control information and then activate the E signal. The module presents no difficulties while

interfacing slower MCU’s.






RS R/W X X X X X X X X

R/W -- Read / Write

R/W -- 1: Data is read from CG RAM / DD RAM

R/W -- 0: Data is written to CG RAM / DD RAM

RS -- Register Select

The Relationship between the operation and the combination of RS, R/W

RS R/W E OPERATION

0 0 Write instruction

code0 1 Read busy flag and

Address Counter

1 0 Write data 1 1 Read data

The Interface timing diagrams and the Read / Write timing diagrams are given below IV

SOFTWARE DESCRIPTION (A) INTRODUCTION Software determines what, how, and where

data is displayed on the LCD. The special features of the built in LCD controller IC are: ¨ Character

Generator ROM (CG ROM) that provides 208 characters with font 5x8 dots and 32 characters with

font 5x10 dots ¨ Character Generator RAM (CG RAM) having a storage function of 8 characterpatterns, which can freely be changed by users program ¨ Display Data RAM with a maximum of 80

characters ¨ Bi-directional 8 or 4 bit data bus interface ¨ Automatic reset on power up ¨ Internaloscillator with an external resistor (No external clock required) ¨ Wide range of instruction

functions including: Display clear, Cursor Positioning, Display or Cursor shift on data entry andDisplay ON/OFF. Display Data RAM (DD RAM): The character to be displayed is written into theDD RAM, in the form of 8 bit character codes present in the character font table. DD RAM can

store a maximum of 80 characters. The display data RAM (DD RAM) that is not used for display

can be used as general data RAM. Depending on the 8-bit character code that is written in to the DD

RAM, LCD will select the character pattern either from Character Generator RAM (CG RAM) or

from Character Generator ROM (CG ROM). Character Generator ROM (CG ROM): The CG

ROM generates 5x8 dot or 5x10 dot character patterns from 8 bit character codes (refer character

font table). It can generate 208, 5x8 dot character patterns and 32, 5x10 dot character patterns.

When an 8-bit character code of the CG ROM is written to the DD RAM, the character pattern of the CG ROM corresponding to the code is displayed on the LCD display position corresponding tothe DD RAM. Character Generator RAM (CG RAM): In the CG RAM, the user can rewrite

character patterns by program. For 5x8 dots, 8 character patterns can be written and for 5x10 dots,4 characters patterns can be written. Programming of these character patterns is explained in CG

RAM programming. (B) INSTRUCTION CODES Instruction codes are the control information

sent by the user, through the micro controller, to the IR and DR of the controller IC, present in the

module. Before starting the internal operation, the controller stores the control informationtemporarily in these registers. The internal operations are determined by the signals sent from the

MCU, which include RS, R/W, E signal and the Data Bus (DB0-DB7). NOTE

DATA For Instruction Register / Data register

§ CLEAR DISPLAY






0 0 0 0 0 0 0 0 1 X


0 0 0 0 0 0 0 1 I/D S


0 0 0 0 0 0 1 D C B


0 0 0 0 0 1 S/C R/L X X

RS -- 0: Selects Command Register for Reading / WritingRS -- 1: Selects Data Register for Reading / writing

RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB00 0 0 0 0 0 0 0 0 1

Loads character code for blank (20H) into all the DD RAM addresses. The cursor returns toaddress 0(Address = “80”) and display, if it has been shifted, returns to the original position. i.e.,

display disappears and the cursor goes to the left edge of the display (to the first line if 2/4 line

display module is used). The Cursor is brought to the first position of first line. Instructionexecution time is 1.52ms.

DB7 – DB0 -- 01H: Clears the Display and all the DD RAM locations

§ RETURN HOME DB7 – DB0 -- 02H , 03H: The cursor goes to the first position of the first line

Returns the cursor to address 0(Address=80) and display, if it has been shifted, to the original

position. The DD RAM contents remain unchanged. Instruction execution time is 1.52ms. §

ENTRY MODE SET I/D = 0: Decrements the address of DD RAM / CG RAM when data is written

to or read from DD RAM / CG RAM. Cursor is shifted left on the display. I/D = 1: Increments the

address DD RAM / CG RAM when data is written to or read from DD RAM / CG RAM. Cursor is

shifted right on the display. S = 0: The Display is not scrolled. S = 1: The display scrolls. Direction

of scrolls depends on the value of I/D. DATA DB7 – DB0 -- 04H: Data written from right to left.

Display is not scrolled. DB7 – DB0 -- 06H: Data written from left to right. Display is not scrolled.

DB7 – DB0 -- 05H: Data written from right to left. Display scrolls. DB7 – DB0 -- 07H: Data written from left to right. Display scrolls. Instruction execution time is 37µS. § DISPLAY ON /

OFF D: The display is ON when D=1, and OFF when D=0. When OFF, the display data remains in

the DD RAM and can be displayed by setting D to 1. C: The cursor is displayed when C=1, and not

displayed when C=0. The cursor is displayed in the 8th line for the character font selection of 5x8

dots. B: The character indicated by the cursor blinks when B=1. The blinking is displayed as

switching between all black dots (dots ON) and displayed character at a speed of 409.6ms intervals

while the controller IC operates at a clock frequency of 250KHZ. DATA DB7 – DB0 -- 08HDisplay OFF DB7 – DB0 -- 0CH Display ON and cursor OFF DB7 – DB0 -- 0EH Display ON and

cursor ON not Blinking DB7 – DB0 -- 0FH Display ON and cursor ON Blinking Instructionexecution time is 37µS. § CURSOR / DISPLAY SHIFT This instruction shifts the cursor / displayto the right or left, without writing or reading the display data. This function is used for correction

or search of display. S/C R/L 0 0 Shifts the cursor position to the left. AC is decremented by one. 0

1 Shifts the cursor position to the right. AC is incremented by one. 1 0 Shifts the entire Display to

the left. Cursor follows the display shift. 1 1 Shifts the entire Display to the right. Cursor follows

the display shift. When the displayed data is shifted repeatedly, each line moves horizontally. The





RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB00 0 0 0 1 DL N F X X


0 0 0 1 ACG ACG ACG ACG ACG ACG


0 0 1 ADR ADR ADR ADR ADR ADR ADR



second line display does not shift in to the first line position. The Address Counter contents wouldnot change, if only, the display shift operation is performed. Instruction execution time is 37µS.

DATA DB7 – DB0 -- 10H: Shifts the cursor position to left DB7 – DB0 -- 14H: Shifts the cursorposition to right DB7 – DB0 -- 18H: Shifts the entire display to left Cursor follows the display

shift DB7 – DB0 -- 1CH: Shifts the entire display to right Cursor follows the display shift §

FUNCTION SET This instruction initializes the system, and must be the first instruction to beexecuted after power on. Instruction execution time is 37µS. DLSets the interface data length to

8-bit when DL=1, and 4-bit when DL=0. N – Sets the Number of Display lines F – Sets theCharacter fontDATA DB7 – DB0 -- 30H: Sets the display as One Line, 5 X 8 dots character size

and data transfer is 8-Bits DB7 – DB0 -- 34H: Sets the display as One Line, 5 X 10 dots charactersize and data transfer is 8-Bits DB7 – DB0 -- 38H: Sets the display as Two Lines, 5 X 8 dots

character size and data transfer is 8-Bits DB7 – DB0 -- 20H: Sets the display as One Line, 5 X 8

dots character size and data transfer is 4-Bits DB7 – DB0 -- 24H: Sets the display as One Line, 5 X10 dots character size and data transfer is 4-Bits DB7 – DB0 -- 28H: Sets the display as Two Lines,

5 X 8 dots character size and data transfer is 4-Bits Note: This instruction also sets the display asfour lines, 5 X 8 dots character in 4-line display modules. § SET CG RAM ADDRESS This

instruction loads a new 6-bit address into the Address Counter and sets it to address the CG RAM.

Henceforth, the contents of the Address Counter will be automatically modified after each access

of CG RAM, as selected by the ‘Entry Mode set’ instruction. If this instruction is issued by the

system MCU while the display is enabled, and if either the cursor or blink is on, the display willblink. To avoid this, both the cursor and display blink should be turned off before loading a new CG

RAM address. Instruction execution time is 37µS. DB7 – DB0 -- 40H to 7EH § SET DD RAM

ADDRESS This instruction loads a new 7-bit address into the Address Counter and sets it toaddress the DD RAM. Data is then written to or read from the MCU for DD RAM. Henceforth, the

contents of the Address Counter will be automatically modified after each access of DD RAM, as

selected by the ‘Entry Mode set’ instruction. Instruction execution time is 37µS. DB7 – DB0 --

80H to CFH for one line display DB7 – DB0 -- 80H to A7H for line one of two-line display DB7 –DB0 -- C0H to E7H for line two of two-line display § DD RAM / CG RAM DATA WRITE This

instruction writes the data in DB7 to DB0 into either the CG RAM/ DD RAM, depending on the

last executed ‘Set CG RAM address’ or ‘Set DD RAM address’ instruction, and the parameters of the instruction. Henceforth, the contents of the Address Counter will be automatically modified as

per the ‘Entry Mode set’ instruction, after each data write operation. Instruction execution time is

37µS. . DB7 to DB0 Data to be written § DD RAM / CG RAM DATA READ The instruction reads

data DB7 to DB0 from CG RAM / DD RAM depending on the type of ‘Set RAM address’instruction last executed. Prior to inputting this read instruction, either the CG RAM address set

instruction or the DD RAM address set instruction must be executed. If it is not done, the first readdata becomes invalid, and data of the next address is read normally from the second read.








0 1 BF AC AC AC AC AC AC AC

Henceforth, the contents of the Address Counter will be automatically modified as per the ‘EntryMode set’ instruction, after each data read operation. Instruction execution time is 37µS. DB7 to

DB0 Data to be read § READ BUSY FLAG (BF) / ADDRESS COUNTER This instruction gives the

current value of the Address Counter and the busy flag status. BF set to 1 indicates that the internal

operation is in progress, and the next instruction will be accepted only after BF is reset to 0. The

next seven bits point to a location, either in CG RAM or DD RAM depending on the ‘Set RAMaddress’ instruction last executed. Instruction execution time is 1µS. BF – BUSY FLAG: AC –

ADDRESS COUNTER VALUE DB6 to DB0 gives the address NOTE: Instruction execution time

changes when frequency changes. (C) INITIALIZATION FLOW FOR 8 BIT AND 4 BIT LCD

MODULES

Power ON

Power ON

Wait for 15 millisecond or more After VDD rises to 4.5VWait for 15 millisecond or more After VDD rises to 4.5V

RS R/W DB7 DB6 DB5 DB4 (Set interface length 8 bit) 0 0 0 0 1 1Set interface length 8 bit RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 1 1 X X X X




Wait for more than 100 µSSet interface length 8 bit RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 1 1 X X X X


Wait for more than 100 µS





Set interface length 8 bit RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 1 1 N F X X

Check for busy flag or give a time delay of 2msSet Display OFF RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 1 0 0 0

Check for busy flag or give a time delay of 2msSet Display Clear RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 0 0 0 1

Check for busy flag or give a time delay of 2msCheck for busy flag or give a time delay of 2ms

RS R/W DB7 DB6 DB5 DB4 (Set interface length 4 bit) 0 0 0 0 1 0 0 0 N F X X

RS R/W DB7 DB6 DB5 DB4 (Set Display OFF) 0 0 0 0 0 0 0 0 1 0 0 0





Check for busy flag or give a time delay of 2msRS R/W DB7 DB6 DB5 DB4 (Set Display Clear) 0 0 0 0 0 0 0 0 0 0 0 1


RS R/W DB7 DB6 DB5 DB4 (Set Entry Mode) 0 0 0 0 0 0 0 0 0 1 I/D S

Check for busy flag or give a time delay of 2msRS R/W DB7 DB6 DB5 DB4 (Set Display Clear & cursor 0 0 0 0 0 0 returns to home position) 0

0 0 0 0 1 End of InitializationCheck for busy flag or give a time delay of 2ms

Set Entry Mode RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 0 1 I/D S


RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 0 0 0 0 0 0 0 0 0 1 SetDisplay Clear & cursor

returns to home position. End of initialization

INITIALIZATION BY INTERNAL RESET CIRCUIT 4.5V

0.2V VDD 0.2V 0.2V TOFF

TRON 0.1 ms ≤ TRON ≤ 10ms TOFF ≥ 1ms POWER SUPPLY RESTRICTION TRON – Power

Supply Rise Time TOFF – Power Supply OFF Time If the electrical characteristics of the powersupply meet the above specification, the internal reset circuit automatically initializes the

controller IC when the power is turned on. The busy flag is kept in the busy state (BF = 1) until theinitialization ends. The busy state lasts for 15ms after VDD rises to 4.5V. The following

instructions are executed by default, during the internal initialization routine: § Display Clear §Function Set: DL = 1 ; 8 Bit Data Interface N = 0 ; 1 Line Display F = 0 ; 5x8 Dot Character Font §

Display on/off control: D = 0 ; Display off C = 0 ; Cursor off B = 0 ; Blinking off § Entry ModeSet: I/D = 1 ; Increment by one S = 0 ; No Shift § DD RAM is selected After power on, if the

Display is not initialized automatically, initialization by instruction should be carried out. (D)

FUNCTIONAL DESCRIPTION OF THE CONTROLLER IC Registers: The controller IC hastwo 8-bit registers, an Instruction Register (IR) and a Data Register (DR). The IR stores the

instruction codes and address information for DD RAM and CG RAM. The IR can be written, but

not read by the Micro Controller Unit (MCU). The DR temporarily stores the data to be written to /

read from the DD RAM or CG RAM. The data written to DR by the MCU is automatically written

to the DD RAM or CG RAM as an internal operation. When an address code is written to IR, the

data (of the specified address) is automatically transferred from the DD RAM or CG RAM to the

DR. Data transfer between the MCU is then completed when the MCU reads the DR. Likewise, for

the next MCU read of the DR, data in DD RAM or CG RAM at the next address is sent to the DR

automatically. Similarly, for the MCU write of the DR, the next DD RAM or CG RAM address is

selected for the write operation. The Register Selection table is as shown below: RS R/WOperation 0 0 IR write as an internal operation 0 1 Read Busy Flag (DB7) and Address Counter(DB0 to DB6) 1 0 DR write as an internal operation (DR to DD RAM or CG RAM) 1 1 DR read as

an internal operation (DD RAM or CG RAM to DR) Busy Flag: When the busy flag is 1, thecontroller is in the internal operation mode and the next instruction will not be accepted. When RS

= 0 and R/W = 1, the busy flag is output from DB7. The next instruction must be written after

ensuring that the busy flag is 0. Address Counter: The Address Counter allocates the address forthe DD RAM and CG RAM Read/Write operation. When the instruction code for a DD RAM

address or CG RAM address setting, is input to the IR, the address code is transferred from IR to

the Address Counter. After writing/reading the display data to/from the DD RAM or CG RAM, the





80 81 82 83 84 85 86 87

80 81 82 83 84 85 86 87 88 89 8A 8B 8C 8D 8E 8F

C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB CC CD CE CF



94 95 96 97 98 99 9A 9B --- --- --- A3 A4 A5 A6 A7

D4 D5 D6 D7 D8 D9 DA DB --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87 --- --- --- A3 A4 A5 A6 A7C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87 --- --- --- A3 A4 A5 A6 A7C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87 --- --- --- A3 A4 A5 A6 A7

C0 C1 C2 C3 C4 C5 C6 C7 --- --- --- E3 E4 E5 E6 E7

80 81 82 83 84 85 86 87

C0 C1 C2 C3 C4 C5 C6 C7

Address Counter increments/decrements the address by one, as an internal operation. The data of the Address Counter is output to DB0 to DB6 while R/W = 1 and RS = 0. (E) DD RAM

LOCATIONS The DD RAM is used to store display data of 8 bit character codes present in the

Character Font Table. The DD RAM address corresponds to specific display position on the LCD.The DD RAM address should be set in the Address Counter, so as to enable the display of

characters on the LCD. DD RAM address is set in the Address Counter (AC) as a hexadecimalnumber. MSB DD RAM Address LSB

1 AC6 AC5 AC4 AC3 AC2 AC1 AC0Note: The DD RAM address is a 7-bit address; the 1 in the MSB is for the controller to identify the

DD RAM address (Ref set DD RAM address instruction in the IV (B) instruction codes)DD RAM

can store a maximum of 80 characters, 01 02 03 04 05 … 78 79 80 80 81 82 83 84 … CD CE CF

(DD RAM Address)

DD RAM ADDRESSES FOR THE DIFFERENT

CRYSTALONICS DISPLAY MODULES:

1 l ine x 8 characters Display Mode 2 line x 8 characters Display Mode LINE1 LINE1 LINE2

1 l ine x 16 characters Display Mode (For CDM

16116 Module)

80 81 82 83 84 85 86 87 C0 C1 C2 C3 C4 C5 C6 C7

2 l ine x 16 characters Display Mode LINE 1 LINE 2

2

line

x 20 characters Display Mode LINE 1 LINE 2

4line

x 20 characters Display Mode LINE 1 LINE 2 LINE 3 LINE 4

1

line

x 32

characters Display Mode

80 81 82 83 84 85 86 87 88 --- --- 9B 9C 9D 9E 9F

2 l ine x 40 characters Display Mode LINE 1 LINE 2

4line

x 40 characters Display Mode LINE 1 LINE 2 LINE 3 LINE 4

Note: Two controllers are required for the 4 line x 40 characters displays. The first one controls

the top 2 lines and the second controls the bottom 2 lines. They share all I/O lines except the “E”





80 81 82 83 84 85 86 87C0 C1 C2 C3 C4 C5 C6 C7

81 82 83 84 85 86 87 88

C1 C2 C3 C4 C5 C6 C7 C8A7 80 81 82 83 84 85 86

E7 C0 C1 C2 C3 C4 C5 C6

Character Codes (DD RAM

Data)

CG RAM Address Character Patterns (CG

RAM Data)

7 6 5 4 3 2 1 0 High Low 5 4 3 2 1 0 High Low 7 6 5 4 3 2 1 0 High Low

0 0 0 0 * 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0

0 0 0 1 0 0 0 0 0 1 1 0 0

0 1 0 0 0 0 0 1 0 1 0 0 0

1 1 0 0 0 0 1 1 1

* * * 1 1 1 1 1 * * * 1 0 0 0

0 * * * 1 0 0 0 0 * * * 1 1 11 0 * * * 1 0 0 0 0 * * * 1 0

0 0 0 * * * 1 1 1 1 1 * * * 0

0 0 0 0

0 0 0 0 * 0 0 1 0 0 1 0 0 0 0 0 1 0 0 1 00 1 0 1 0 0 0 1 0 1 1 0 01 1 0 0 0 0 1 1 0 1 0 0 1

1 1 0 0 0 1 1 1 1

* * * 0 0 1 0 0 * * * 0 1 1 10 * * * 0 1 1 1 0 * * * 0 1 11 0 * * * 0 1 1 1 0 * * * 1 1

1 1 1 * * * 0 0 1 0 0 * * * 00 0 0 0

0 0 0 0 * 0 1 0 0 1 0 0 0 0 0 1 0 0 0 1 * * * 1 0 0 0 1 * * * 1 1 0 1

10 0 0 0 * 1 1 1 1 1 1 1 0 1 1 1 1 1 1 0 1

1 1 1 1 1

* * * 0 0 1 0 0 * * * 0 1 0 1

0 * * * 1 1 0 1 1

signal. Hence independent “E” signals should be applied to the controllers. Example for Display

Shift using 2 line x 8 characters Display Mode: Before executing Shift LINE 1 LINE 2 Display

Shifted Left (S/C = 1, R/L =0.Ref IV (B) InstructionCode Curser/Display Shift) LINE 1 LINE 2 Display

Shifted Right (S/C = 1, R/L = 1.Ref IV (B) Instruction

Code Curser/Display Shift) LINE 1 LINE 2 (F) CG

RAM PROGRAMMING The CG RAM allows the

user to create special characters or symbols, usingsoftware. For 5x8 dot format, 8 character patterns and for 5x10 dot format, 4 character patterns can

be programmed. These characters can be accessed as if they were in the CG ROM. These special

characters can be displayed by mentioning the character codes 00H07H or 08H0FH (Ref IV

(G) Character font table). Thus the CG RAM expands the character representation available to the

user. For 5 x 8 DOT CHARACTER PATTERN: Programming Character Patterns in the CG

RAM: Enter the CG RAM address, using the instruction “Set CG RAM Address”. The three bits of

CG RAM address, bits 0-2, correspond to the line position of each character pattern. Using the

instruction “CG RAM data write”, enter the character pattern data, line by line. The data bus lines

DB0-DB7, correspond to CG RAM data bits 0-7. The CG RAM address would be automatically

incremented/ decremented as per the entry mode set instruction executed. The correspondingpixels of the character pattern is activated if it is set to 1 and not activated if it is set to 0. The last

line of the character pattern that is the cursor position should all be 0s. Displaying characterpatterns on the LCD: The CG RAM is selected, when the four higher order bits (bit 4-bit 7), of the

8 bit character codes, are all 0s. When the character pattern’s 8-bit character code is written to thecorresponding DD RAM address of the display, the special characters are displayed. The limitation

of 8 special characters can be overcome by creating a library of customs symbols, with each settotaling 8 characters. These 8 characters can be displayed at one go, by reloading the CG RAM with

different sets of character patterns. This is a RAM, and must be programmed if display power is

interrupted. If used regularly, programming can be made part of the initialization routine. CGRAM, DD RAM, and pattern examples for 5 x 8 Dot character patterns Character Pattern

Example (1)

Cursor Position

Character

Pattern Example

(2) Cursor

Position

Character

Pattern Example

(8) CursorPosition * Don’tCare Notes: §

Character codebits 0-2

correspond to

CG RAMaddress bits 3-

5 for a total of

8 patterns. § CG RAM address codes 0-2 designate character pattern line. The 8th line is the cursor





position. It is logically ‘OR’ed with the cursor instruction. § Character patterns are loaded in to CGRAM data bits 0-4 as shown in the table. Since CG RAM bits 5-7 are not used, they may be used for

general data RAM. § CG RAM patterns are displayed on the LCD when character code bits 4-7 are

all “0”. Bit 3 is a don’t care bit. Therefore, character pattern (1) can be selected with character code00H or 08H. § “1” in the character pattern turns a dot “ON”. “0” indicates a non-selected dot. Flow

of CG RAM programming:

Set DD RAM Data

Set DD RAM AddressSet CG RAM Address

Set CG RAM Data

Initialize the LCD

(G) CHARACTER FONT TABLE

V PRECAUTIONS (A) POWER SUPPLY PRECAUTIONS § Always check the

absolute maximum rating of the LCD driver. § The polarity of the supply voltage should not bereversed. § Use a clean power source free from transients. § The ground terminal of the power

supply must be isolated properly so that no voltage is induced in it. § The module should be isolatedfrom the other circuits, so that stray voltages are not induced, which could cause a flickeringdisplay. § The +5V power for the module should also supply the power to all devices, which may

access the display. Don’t allow the data bus to be driven when the logic supply is disabled. § VDD

must, at all times, exceed the VL voltage level. Do not install a capacitor between the VL pin and

ground. The capacitor combines with the contrast potentiometer to form an R-C network, which

“holds-up” VL, at the power-down, damaging the module. (B) MECHANICAL PRECAUTIONS §

Cover the display surface with a transparent protective plate, to protect the polarizer. § Mount the

module so that it is free from torque and physical loads. § Do not use organic solvents to clean the

display panel as these may adversely affect the polarizers. Dust may be removed by adhesive tape or

with absorbent cotton and petroleum benzene. § Ensure that the soldering is proper, as drysoldering causes improper character display. § The processing or even a slight deformation of the

claws of the metal frame will have effect on the connection of the output signal and cause anabnormal display. § Do not damage or modify the pattern writing, or drill attachment holes in the

PCB. When assembling the module into another equipment, the space between the module and the

fitting plate should have enough height, to avoid causing stress to the module surface. § Make surethat there is enough space behind the module, to dissipate the heat generated by the IC’s while

functioning for longer durations. § Employ anti-static procedures while handling the module. (C)

ENVIRONMENTAL PRECAUTIONS § Prevent moisture build-up on the module. § Contact with

water or oil over a long period of time may cause deformation or color fading of the display.Condensation on the terminals can cause electro-chemical reaction disrupting the terminal circuit.

§ Operate the LCD module under the relative condition of 40ºC and 50% relative humidity. Lower

temperature can cause retardation of the blinking speed of the display, while higher temperatures

make the overall display discolor. Polarization degradation, bubble generation or polarizer peel off

may occur with high temperature and humidity. § Do not store in direct sunlight. (D) OPERATING

PRECAUTIONS § A module should not be inserted or removed from a live circuit. § Minimize the

cable length between the module and the host. Long lengths may introduce noise or damagingvoltages due to antenna-effect. § Don’t touch the display surface with bare hands or any hard

materials. This will stain the display area and degrade the insulation between terminals. VI





TROUBLESHOOTING q No Data is displayed § Check if the power supplied (VDD, VL, VSS) isas per the Data sheet specification. § Check the Interface connections. Ensure that there are no I/O

pads bridged. § Check the supply current. Ensure IC’s and resistors are not heated. Immediately turnoff the power before checking the connection, if it is heated. q Improper initialization § Check if

the initialization routine is as per the Data Sheet. § See if the system is operated without making a

BUSY FLAG check. If so, make a BUSY FLAG Check. § Check if the interface pins (RS, R/W, Eand DB0-DB7) are connected properly or not. § Check the signal timings. Check that all setup

times are followed. q Improper Character Display § When the characters to be displayed aremissing in between, the data read/write is too fast. A slower interfacing frequency would rectify the

problem. § If a character not found in the font table is displayed, or a character is missing, the CG

ROM is faulty and the controller IC has to be changed. § In a multi line display, if the display of

characters in the subsequent lines doesn’t take place properly; send proper DD RAM Addresses in

the initialization code. § The display ON / OFF flag is turned OFF by the internal initialization

routine. This flag has to be explicitly turned ON and it is always better to send an initialization

routine after power up. § If particular pixels of the characters are missing, or not getting activated

properly, there could be an assembling problem in the module. q Data cannot be read § Check if the

connections and polarity of RS and R/W are as per the manual specification. § Check if there is a

contention between any peripheral equipment and the data bus. § Check the signal timings. Checkthat all setup times are followed. § See if the system is operated without making a BUSY FLAG

check. If so, make a BUSY FLAG Check. § Check for errors in the software. q In case any otherproblems are encountered, you could send the module to our factory for testing and evaluation.

CRYSTALONICS DISPLAYS Bright Future…

CONTACT INFORMATION: CRYSTALONICS DISPLAYS (P) LTD

PLOT NO 38,SIPCOT PHASE II,HOSUR, TAMIL NADU, INDIA.

TEL: 04344-260 389/199

FAX: 04344-260391MOBILE:09944977176

E-Mail: [email protected] & [email protected] MARKETING OFFICES:

BANGALORE DIGIPROTEK 403, 6th main, 1st Cross, HAL 2nd Stage, Bangalore -- 560 008.

Telephone: 080- 25266706 / 25272659 / 25262639 Fax: 25263088 E-mail:

[email protected] Web Site: www.digiprotek.com NEW DELHI DIGIPROTEK Flat No. 2C,

Masjid Moth-1 G.K. Part III, New Delhi – 110 048 Telephone: 011- 26242297 / 26241604

Telefax: 011 - E-mail: [email protected] HYDERABAD DIGIPROTEK No. 28, Suman Housing

Colony, West Marredpally, Secunderabad - 500 026 Telephone: 040 – 55214521 Telefax: 040 -

27807278 E-mail: [email protected] All Rights Reserved. © 2003 Crystalonics Displays

Private Limited, India. MARKETING OFFICES: BANGALORE DIGIPROTEK 403, 6th main,1st Cross, HAL 2nd Stage, Bangalore -- 560 008. Telephone: 080- 25266706 / 25272659 / 25262639 Fax: 25263088 E-mail: [email protected] Web Site: www.digiprotek.com NEW

DELHI DIGIPROTEK Flat No. 2C, Masjid Moth-1 G.K. Part III, New Delhi – 110 048 Telephone011- 26242297 / 26241604 Telefax: 011 - E-mail: [email protected] HYDERABAD

DIGIPROTEK No. 28, Suman Housing Colony, West Marredpally, Secunderabad - 500 026

Telephone: 040 – 55214521 Telefax: 040 - 27807278 E-mail: [email protected] All RightsReserved. © 2003 Crystalonics Displays Private Limited, India.





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