Eng .Samra EssalaimehEng .Samra EssalaimehPhiladelphia UniversityPhiladelphia University

2013/20142nd Semester

PIC MicrocontrollersPIC Microcontrollers

Computer Systems

The PC system main unit.

PC motherboard

Block diagram of PC motherboard.

Word processor Operation

PC Microprocessor System

Block diagram of PC microprocessor system.

System Operation

•Program ExecutionThe ROM and RAM memory contain program information and data in numbered locations.The ISD contains address decoding logic which allocates a particular memory chip to a range of addresses. The I/O port registers, which are set up to handle the data transfer in and out ofthe system, are also allocated particular addresses by the system designer, and accessed by the CPU in the same way as memory locations.

•Execution Cycle

PC Engineering Applications

The MicrocontrollerThe microcontroller can provide, in a

simplified form, all the main elements of the conventional microprocessor system on a single chip.

less complex applications can be designed and built quickly and cheaply

A Microcontroller Application

Microcontroller keypad display system

Programming a Microcontroller

Information CodingNumber Systems: 1.Decimal: Base 10

2. Binary: Base 2

3. Hexadecimal: Base 16

hexadecimal is used as a way to represent binary numbers in a compact way, while allowing easy conversion back to the original binary

Examples of equivalent values

Counting:The rules for counting in any number system:1.Start with all digits set to zero.2. In the right digit position (LSB), count up from zero to the maximum digit available (1 in binary, 9 in decimal, F in hexadecimal). 3. If a column value is at its maximum, reset it to zero, and increment (add 1 to) the next column to the left.In microprocessors, there is a fixed number of digits in the registers which store binary numbers (8, 16, 32 bits or more). If the number storage space has a fixed number of digits, leading zeros must be used to fill the empty positions, because each register bit must be either 1 or 0, and leading zeros do not alter the value.

Bits, Bytes and Words:

One binary digit represents a ‘bit’ of information. A group of 8 bits is called a ‘byte’, and larger binary codes are called ‘words’. This last term is used fairly loosely, but it sometimes refers to a 16-bit code, with a 32-bit code called a ‘long word’, specifically in the Motorola 68000 CPU, which was widely used in the past. As we now know, in hexadecimal four bits are represented by one hex digit, so a byte is 2 hex digits, and so on. Thus, register and memory values are typically displayed as hexadecimal numbers with 2, 4, 8, 16 . . . digits.

Machine Code ProgramsData Words:

Machine Code

8086 Machine Code

PIC Machine Code

ASCII Code:ASCII (American standard code for information interchange)

is a type of binary code for representing alphanumeric characters, as found on your computer keyboard.

The basic code consists of seven bits. For example, capital (or ‘upper case’) ‘A’ is represented by binary code

100 0001 (65), ‘B’ by 66, and so on to ‘Z’ = 65+25 = 90 = 101 10102. Lower case letters

and other common keyboard characters such as punctuation, brackets and arithmetic signs, plus some special control characters also have a code in the range 0–127. The numerical characters also have a code, for example ‘9’ = 011 10012, so you sometimes need to make it clear if the code is the binary equivalent 10012 or the ASCII code 011 10012.