1. ES C263 Microprocessor Programming and Interfacing
Lecture 2
ES C263 Microprocessor Programming and Interfacing

2. ES C263 Microprocessor Programming and Interfacing
Last Lecture
Evolution of Computers and Microprocessors
Moore's Law
ES C263 Microprocessor Programming and Interfacing

3. ES C263 Microprocessor Programming and Interfacing
Today's Lecture
Instruction Set Architecture
Overview of a Microprocessor
Design Example
ES C263 Microprocessor Programming and Interfacing

4. Processor (8086 through Pentium
The Personal Computer
Speaker
Processor (8086 through Pentium
Timer logic (8253)
Coprocessor (8087 through
System ROM
640KB DRAM
System bus (data, address & control signals)
Keyboard logic (8253)
DMA Controller (8237)
Expansion logic
Interrupt logic (8259)
Video card
Disk controller
Serial port
Keyboard
...
ES C263 Microprocessor Programming and Interfacing
Extension slots

5. Instruction Set Architecture (ISA)‏
ISA refers to the actual set of programmer visible instruction set.
Serves as a boundary between the hardware and software.
Seven dimensions of ISA
Class of ISA: general purpose register architectures, where operands are either memory or register locations.
ES C263 Microprocessor Programming and Interfacing

6. ES C263 Microprocessor Programming and Interfacing
Memory Addressing: Byte addressing to access memory locations.
Addressing Modes: specify the address of register, constant operands and memory objects- - register, immediate, displacement.
ES C263 Microprocessor Programming and Interfacing

7. ES C263 Microprocessor Programming and Interfacing
Types and sizes of operands: supports operand sizes of 8 bit, 16 bit, 32 bit.
Operations: data transfer, arithmetic, logic, control.
Control flow instructions: support conditonal branches, unconditional jumps, procedure calls and returns.
Encoding an ISA: fixed length or variable length.
ES C263 Microprocessor Programming and Interfacing

8. ES C263 Microprocessor Programming and Interfacing
ES C263 Microprocessor Programming and Interfacing

9. ES C263 Microprocessor Programming and Interfacing
Memory Overview
ES C263 Microprocessor Programming and Interfacing

10. ES C263 Microprocessor Programming and Interfacing
ES C263 Microprocessor Programming and Interfacing

11. Evolution of programming: machine language
late 40’s / early 50’s: programmers coded directly in machine language
each machine had its own set of instructions (sequences of 0's & 1's) corresponding to its underlying hardware
 extremely tedious, error-prone
ES C263 Microprocessor Programming and Interfacing

12. ES C263 Microprocessor Programming and Interfacing
-Fetches Instruction
-Executes Instruction
ES C263 Microprocessor Programming and Interfacing

13. ES C263 Microprocessor Programming and Interfacing
Computer Hardware Organization
Example: 3 Instructions of a program
Input Value from port 05
Add 7 to this value
Output the result to port 02
Control
unit
common bus
Arithmetic
logic
unit
memory
output
input
Registers
program
data
unit
unit
storage
storage
ES C263 Microprocessor Programming and Interfacing

14. ES C263 Microprocessor Programming and Interfacing
Add
Bus
CPU
Data
Bus
Control
signals
ES C263 Microprocessor Programming and Interfacing

15. ES C263 Microprocessor Programming and Interfacing
Memory
Add Bus
Data Bus
Read
Write
Memory – Registers to hold bits
ES C263 Microprocessor Programming and Interfacing

16. ES C263 Microprocessor Programming and Interfacing
Ex :
8 Registers
4 bits
Add lines : 3 (Unidirectional)‏
Data lines : 4 (Bidirectional)‏
ES C263 Microprocessor Programming and Interfacing

17. ES C263 Microprocessor Programming and Interfacing
Design Example
ES C263 Microprocessor Programming and Interfacing

18. ES C263 Microprocessor Programming and Interfacing
Design a microprocessor based system to control pH of a solution in a reactor tank.
User enters desired pH (0-14) and controller gain
Reactor tank provided with three pH sensors, to compute the average pH.
Reactor tank has three inputs.
(acid, base flow controlled by valves, effluent discharged from factory)
ES C263 Microprocessor Programming and Interfacing

19. ES C263 Microprocessor Programming and Interfacing
Valve Control
Controlled by stepper motors
1 step is by 1.8 degrees rotation
Valve opening = kP * error
Where error = desired pH – measured pH.
Error positive- close fully acid valve and open base valve accordingly
Error negative- close fully base valve and open acid valve accordingly.
0 – 360 degrees correspond to 0 to 200 steps.
ES C263 Microprocessor Programming and Interfacing

20. ES C263 Microprocessor Programming and Interfacing
Parallel I/O
Serial I/O
Memory
I/O Interface
CPU
Data
Address
Control
ES C263 Microprocessor Programming and Interfacing

21. ES C263 Microprocessor Programming and Interfacing
Stepper Motor sequence:
A B C D
ACW CW
Use a 4- bit port driver (nearly 1 A current)
ES C263 Microprocessor Programming and Interfacing

22. ES C263 Microprocessor Programming and Interfacing
pH sensor
Vout pH 7 14
Voltage output 60mV/pH
-420mV mV
ES C263 Microprocessor Programming and Interfacing

23. ES C263 Microprocessor Programming and Interfacing
Interfacing Analog to Digital Converter
8-bit ADC I0 I7 D0 D7
Start A B C
EOC OE
ALE
ADC 0809
ES C263 Microprocessor Programming and Interfacing

24. ES C263 Microprocessor Programming and Interfacing
Input Keys
Numeric keys 0 – 9
Function keys
pH, kP, enter
Matrix Keypad interfacing!!
- 2 four bit ports.
ES C263 Microprocessor Programming and Interfacing

25. ES C263 Microprocessor Programming and Interfacing
Two digit Display
Two seven segment display devices to display pH
Memory Interfacing
ROM (4K) - FF000H – FFFFFH
SRAM (4K) H – 00FFFH
ES C263 Microprocessor Programming and Interfacing

26. ES C263 Microprocessor Programming and Interfacing
Method of Approach
Identify input and output devices
Memory requirements
Suitable memory and I/O interfacing
ALP
Assumptions made
ES C263 Microprocessor Programming and Interfacing