Proportional Motor Controller PMC V1

Copyright Global Innovations Technologies GLINTEC2006

Reproduction forbidden without Global Innovation Technologies’ written authorization - All Rights Reserved

Proportional Motor Controller

(PMC) Ver. 1.0 ON-OFF & Proportional Controller

Embedded System By GLINTEC®

The PMC is a helpful platform designed for implements

control systems like temperature control system and speed

control system in CD motors (rpm) and stepper motors too.

This manual explains some features of the PMD platform; the

system is based in the PIC microcontroller 16F882.

High-Performance RISC CPU:

• Operating speed: - DC – 20 MHz

oscillator/clock input - DC – 200 ns instruction cycle

Special Microcontroller Features:

• Precision Internal Oscillator:

- Software selectable frequency range of

8 MHz to 31 kHz - Software tunable

- Crystal fail detect for critical applications

• Wide operating voltage range (2.0V-5.5V)

• Industrial and Extended Temperature range • High Endurance Flash/EEPROM

cell: - 100,000 write Flash

endurance - 1,000,000 write EEPROM

endurance - Flash/Data EEPROM

retention: > 40 years

• Program memory Read/Write

during run time • In-Circuit Debugger (on

board) Low-Power Features:

• Standby Current: - 50 nA @ 2.0V, typical • Operating Current:

-11 μA @ 32 kHz, 2.0V,

typical

-220 μA @ 4 MHz, 2.0V, typical • Watchdog Timer Current:

-1 μA @ 2.0V, typical Peripheral Features: • 24/35 I/O pins with

individual direction control: - High current source/sink

for direct LED drive - Ultra Low-Power Wake-up (ULPWU)

• Analog Comparator module

with:

- Two analog comparators - Programmable on-chip

voltage reference (CVREF) module (% of VDD)

- Fixed voltage reference (0.6V)

• A/D Converter: - 10-bit resolution and 11/14

channels • Enhanced USART module:

- Supports RS-485, RS-232, and LIN 2.0

• In-Circuit Serial

Programming TM (ICSPTM) via two pins



The schematic of the IC is showed in the figure below

for more information about the Pic 16f882, refer to

[Microchip].

Figure 1.1. PIC 16F882 Schematic.

2. Features of PMC platform.

PMC platform can be programmed externally for implements

ON-OFF controller or Proportional plus Bias controller. Each

one has its parameter range from 0 to 100% in increments of

10%. For program the parameter(s) in the controller; the

user has to implement an interface with three buttons each

one manipulates the increment, decrement and enter. The

values of the parameters can be displayed into LCD display;

specifically a “parallel LCD display” of two lines (see

figure 2.2).

Figure 2.1. Configuration Pins of the LCD display.

When the circuit is turn on, in the LCD you must to see

a shift message like show in the figure 2.2.

Figure 2.2. Initializing PMC.



Continuing with the sequence appears a message which

displays the name of the application “PROPORTIONAL MOTOR

CONTROLLER” (PMC V1.0). If everything is correct, you must

to see other label; “Sel Opc...” (Select option) you can

select three options of control.

1. Controlling a Servo Motor.

2. Controlling a Stepper Motor.

3. Controlling a Direct Current Motor.

Each one will be explained in the next sections.

Figure 2.3. Select option.

For select a specific option, you must enter an easy

code, only pressing one or two buttons (see sections 3 to

5).

3. Controlling a stepper motor.

Stepper motor is an actuator very useful in robotics,

because it has a high precision to pose the final actuator

in a manipulator, or get the odometry in mobile robotics.

There are two kinds of stepper motors, unipolar and bipolar,

each one has pros and cons, the difference in these

actuators are the number of pins, the first has 4 terminals

and the second 6 terminals; but this chip is capable to

control both, one schematic is showed in the figure 3.1.

Figure 3.1. Unipolar and bipolar stepper motor

The user can control a stepper motor through these steps:



1. Select the routine named “Stepper Motor Controller”

(PRESSING THE DECREMENT BUTTON), in the LCD appears

“Stepper Motor”.

2. Put the number of degrees to move the stepper motor (SM)

pressing the increment or decrement button. Remember

that you’re using a relative reference, i.e, the initial

position is 0°, you can select (1°, 180°] in range (only

half turn). Obviously, the range is only half turn but

is not a weakness of the platform because you can set

more than 1 spin if you wish (maximum 180). Now if you

agree with the value, press the enter button.

3. In these step you must assign the proportional gain (Kp)

try to assign the optimum gain pressing the increment or

decrement button; remember that the gain is the main

element into the controller if you don’t set a correct

gain, probably you’ll see an unexpected behavior. When

you’re agree with the proportional gain value (Kp) press

the enter button.

4. The third parameter to set is the number of turns, by

default is assigned to 1 but you can set other value

(maximum 180), just press the increment decrement

button; if you finish to setting the value, press enter.

5. Enjoy the sequence that you programmed.



Example I. The current example shows step by step how to run

a sequence in the Control Stepper Routine. Suppose that you

want to set the reference to 90°, remember that the current

position is in 0° (relative position) so:

1. Select the routine named Stepper Motor Controller” in

the LCD menu then press enter.

2. Put the number 90 into var[0], these are the degrees

value in this example; then press the enter button.

3. Press the increment button and set the value to 1; in

this case we don’t want to get more than 1 turn; press

enter.

4. Probably in this case, the current value of the

proportional gain is not correct but only is an example,

the value assigned is 32, press the enter button.

5. Now watch what happen with your earlier assignations.

Does it work correct? Was it the 90°?

Example II. In the previous example only we want 90° but

in this the reference will be 360°+90°=450°, is the same

to 1 turn 90°. Remember that is not possible to assign

450° in the platform, but, how can we do it? Well just

follow the steps:

1. Select the routine named “Stepper Motor Controller” in

the LCD menu then press enter.

2. Put the number 90, this is the degrees in this example

and then press the enter button.



3. Press the increment button and set the value to 1; in

this case we want to get 1 turn (360° more); press

enter.

4. The current value of the proportional gain is set up to

34, if you make the previous example you observed that

the current value was 32 this is because the system has

a local memory and preserve the earliest values. Press

the enter button.

5. Does it work correct? Was it the 450°?

4. Controlling a Servo motor.

Servo motor is likewise an actuator very useful in

robotics; there are 2 kinds of servo motors, each with an

operational range of 0 to 90° or 0 to 180°. The main

features are the high torque, the precision and few

connections only 3 wires 2 of them are to supply the energy

and the third for control the orientation; one picture in

the figure 4.1.

Figure 4.1 Servo motor.

The user can control the servo motor through these steps:

1. Select the routine named “Servo Motor Controller”

(PRESSING THE INCREMENT BUTTON) in the LCD appears the

label “Servo Motor Controller” and starts to blink one

led (indi_1).



2. Enter the number of degrees to move the servo motor

pressing the increment or decrement button. Remember the

servo motor has limits 90° or 180° so the value must be

consistent with the specifications of your servo. Now if

you agree with the degrees to move, press the enter

button.

3. The second parameter to set is the proportional gain it

must be between 0 to 100%, by default is assigned to 0

but you can set other value (maximum 180), just press

the increment decrement button; if you finish to setting

the value, press enter.

4. Although there are a third variable to be entering this

has a value of 1 by default, so if you want to press

enter no problem!.

5. Enjoy the sequence that was programmed you must see in

the LCD something similar to the following figure.

5. Controlling a CD motor (Fan).

This section explain about how you can control a current

direct control, like a fan of CD, with this you can control

the temperature inside of a canister. Controlling the



temperature is very important in the industry, many process

needs a specific temperature to produce a good product. This

section.

The user can control the temperature using a CD motor (fan):

1. Select the routine named “Temperature Controller”

(PRESSING THE INCREMENT BUTTON and DECREMENT at the

same time) in the LCD appears the label “Temperature

Controller” and starts to blink one led (indi_3).

2. The first value is the degrees; if you’re using the LM35

temperature sensor, you will have measurements in

Celsius; otherwise like LM34 you’ll Fahrenheit degrees.

For a correct use of the PMC use a LM35. The operational

range is in 1 to 100°C (check the datasheet about LM35).

3. The second variable to introduce is the proportional

gain, with this and like before, you’re using a

proportional controller and the gain is in percentage (0

to 100%) try to set a correct value for your system. Now

if you agree with the constant (Kp), press the enter

button.

4. Finally the third variable is the Bias value, you can

put it or not, remember is only a Bias in the

controller. The limits are 1 to 180.

5. After all, you must see something like this in your LCD,

where SP means Set Point of the temperature that you set

in the step 2 and CT (Current Temperature) is the

temperature that measures the LM35. If you see the value

65530 like in the figure, means that the LM35 doesn’t

work properly, or there is nothing connected in the PMC.

6. Enjoy your sequence that was programmed.



6. Connecting the PMC in your test board.

In this section you learn how to wire your own circuit

for control 3 different kinds of motors, put attention while

you connect the sources and remember, the motor is an

actuator with much more current sink than the

microcontroller, probably you must have a different source

to supply them. The schematic configuration of the PMC

platform is showed in the figure 6.1.

Figure 6.1. Configuration of the PMC

The CI has 28 pins each one with a function to control a

specific actuator, to display information and to acquire the

signal input through the sensor or pressing the buttons. The

basic connections for this platform are explained in

follows.

6.1 Visual Indicator Section.

Each device must has a signal that specifies if it works

properly or not, the best form is using visual indicators

like lamps or leds, PMC has three indicators leds to ensure

its correct performance; each one is active when a specific

subroutine is active; the led is blinking while the program

is executing. Figure 6.1.1 shows a proposed connection with

the PMC.



Figure 6.1.1. Schematic Indicators.

6.2. Selecting Section.

Now you know that the PMC has three modes of control

(Servo motor Control, Stepper Motor Control and Temperature

control), the way to accede at one subroutine is by 3

buttons in the same form you must assign the values of

reference signal and gain’s controller.

Figure 6.2.1. Schematic Indicators.

6.3. Fan Controller Section.

This section provides a simple circuit to operate a fan

DC the objective is keep constant temperature inside a

canister, remember the DC motor it cannot be connected

directly to the PMC. A schematic diagram for connected is

showed in the figure 6.3.1; keep in mind that if your Fan

needs more than 500 mA and 12 VCD probably you must design

other circuit.



Figure 6.3.1. Connecting a Fan

6.4. Stepper Motor Controller Section.

This section shows a schematic to interface with a

bipolar Stepper motor the circuit to use is the H bridge

L293B IC for protect the PMC platform like showed in the

figure 6.4.1.

Figure 6.4.1. Interfacing a Bipolar SM.

6.5. LCD Section.

The LCD gives a easy way to see the values and data

points that the PMC platform is sending, and the values that

you are entering into the controller. You find in this

section a schematic to implement (Figure 6.5.1); in the

right side you can see the pins assignation of the PMC

platform. While in the figure 6.5.2 shows the virtual board

(double layer) within the specifications of the components

shown in the last sections.



Figure 6.5.1. LCD and PMC schematic section.

Figure 6.5.2. Virtual board of PMC top and bottom layer.



Notes:

Documents

Proportional Motor Controller PMC V1