1. 15: Microprocessor and microcontroller
Lecture 14

2. 15.1: Control
µprocessor systems – use as control system and are term as embedded microprocessor
Dedicated to controlling a specific function
Self-started, self-contained with own operating program
Requiring no human intervention

3. 15.2: Microprocessor systems
Have 3 parts:
Central processing unit (CPU) – recognise and carry out program instruction
Input/output interface – handle communication between computer and outside world
Memory – to hold program instructions and data
µprocessor with memory and various input/output arrangement all on the same chip - microcontroller

4. 15.2.1: Busses
Digital signals move from one section to one another along paths called buses
Data bus – data associated with processing function of CPU
Address bus – indicate where data to be found, selection of memory or input/output ports
Control bus – carry out signals related to control actions i.e. READ, WRITE

5. General form of microprocessor system

6. 15.2.2: General architecture of µp
Arithmetic and logic unit (ALU) – to perform data manipulation
Register – temporarily hold internal data that CPU is currently used
Control unit – determine timing and sequence of operations

7. General internal architecture of microprocessor system

8. Registers – temporary storage
Accumulator – data for i/p to ALU
Status register – flags, indicate status of latest operation
Program counter (PC) or instruction pointer (IP) – keep track position of instruction in a program
Memory address – address of data
Instruction register (IR) – store instruction
General purpose register – temporary storage for data or address
Stack pointer register (SP) – form address which defines top of stack in RAM

9. 15.2.3: Memory
Memory unit – stores binary data and takes the form of one or more integrated circuits
ROM – read only memory, fixed program i.e. operating system
PROM – programmable ROM, used for ROM chip that can be programmed by user
EPROM – erasable and programmable ROM,
EEPROM – electrical and erasable PROM, erasure b high voltage
RAM – random access memory, temporary data
Programs stored in ROM – firmware, RAM used program storage - software

10. 15.3: Microcontroller
Integration of a microprocessor and input/output interfaces and other peripherals such as timers, on a single chip
Has pins for external connections –i/o, power, clock, control signals
i/o ports – single port 8-bit word or two ports 16-bit word

11. Block diagram of a microcontroller

12. Micro
Small, Compact
Controller
Read inputs 
Process
Produce output

13. Applications of Microcontroller
Electronic gadget
Mobile phone
Toys
Robotics
Radio
DVD player
etc

14. There are a lot of different microcontrollers available in the market
There are a lot of different microcontrollers available in the market. For example, Atmel, Motorola, Intel and PIC.
Each one has its own advantages and disadvantages.
There are a lot of similarities between the microcontrollers.
Emphasis on PIC16F877A.

15. 15.3.3: Microchip microcontroller
PIC microcontroller – Peripheral Interface Controller
E.g. PIC16AXX, PIC16FXX,
Harvard architecture – instruction are fetched from program memory using busses that are distinct

16. Harvard architecture

17. PIC16C74A

18. Why PIC?
Easy to buy, inexpensive, low cost development tools and powerful.
You can get from Farnell, RS and Hitectron. You can even get free sample from Microchip website.
The development software is distributed as freeware (MPLAP, PCCLITE and ICPROG).
One basic microcontroller system cost less than RM 50.

19. CORE PIC FAMILY PICs come with 1 of 4 CPU ‘cores’:
12bit cores with 33 instructions: 12C50x, 16C5x
14bit cores with 35 instructions: 12C67x,16Cxxx,16Fxxx
16bit cores with 58 instructions: 17C4x,17C7xx
‘Enhanced’ 16bit cores with 77 instructions: 18Cxxx, 18Fxxx

20. PACKAGING PIC FAMILY PICs come in a huge variety of packages:
8 pin DIPs, SOICs: 12C50x (12bit) and 12C67x (14bit)
18pin DIPs, SOICs: 16C5X (12bit), 16Cxxx (14bit), 16Fxxx (14bit)
28pin DIPs, SOICs: 16C5X (12bit), 16Cxxx (14bit), 16Fxxx (14bit)
40pin DIPs, SOICs: 16Cxxx (14bit), 17C4x (16bit)
pin PLCCs*: 16Cxxx (14bit), 17C4x / 17Cxxx (16bit)

21. SPEED PIC FAMILY PICs require a clock to work.
Can use crystals, clock oscillators, or even an RC circuit.
Some PICs have a built in 4MHz RC clock. Not very accurate, but requires no external components!
Instruction speed = 1/4 clock speed (Tcyc = 4 * Tclk)
All PICs can be run from DC to their maximum spec’d speed:
12C50x 4MHz
12C67x 10MHz
16Cxxx, 16Fxxx 20MHz
17C4x / 17C7xxx 33MHz
18Cxxx, 18Fxxx 40MHz

22. MEMORY PIC FAMILY PIC program space is different for each chip.
Some examples are:
12C bit instructions
16C71C 1024 (1k) 14bit instructions
16F84A 1024 (1k) 14bit instructions
16F (8k) 14bit instructions
17C (16k) 16bit instructions

23. PROGRAM MEMORY PIC FAMILY
PICs have two different types of program storage:
1. EPROM (Erasable Programmable Read Only Memory)
Needs high voltage from a programmer to program (~13V)
Needs windowed chips and UV light to erase
Note: One Time Programmable (OTP) chips are EPROM chips, but with no window!
PIC Examples: Any ‘C’ part: 12C50x, 17C7xx, etc.
2. FLASH
Re-writable (even by chip itself)
Much faster to develop on!
Finite number of writes (~100k Writes)
PIC Examples: Any ‘F’ part: 16F84, 16F87x, 18Fxxx (future)

24. DIGITAL I/O PORT PIC FAMILY
All PICs have digital I/O pins, called ‘Ports’
the 8pin 12C508 has 1 Port with 4 digital I/O pins
the 18pin 16F84A has 2 Ports with 13 digital I/O pins
the 40pin 16F877A has 5 Ports with 33 digital I/O pins
the 68pin 17C766 has 9 Ports with 66 digital I/O pins
Ports have 2 control registers
TRISx sets whether each pin is an input or output
PORTx sets their output bit levels
Most pins have 25mA source/sink (directly drives LEDs)

27. 15.4.2: Application- Domestic washing machine
A. Inputs
water temperature, motor speed – ADC
Water level switch – Port A
B. Outputs
Hot/cold water valve
Water pump control
Door lock
Buzzer
Motor direction
Heater control

28. 15.4.2: Application- Domestic washing machine (cont.)
C. Outputs
Displays
Inputs from keyboards
D. Others
PWM – provide signal to motor
Interrupt – stopped if interrupt i.e. door opened

29. Domestic washing machine

30. 15.5: Programming steps
Define problem – function to perform, i/o required, constraints – speed, accuracy, memory size, etc.
Define algorithm – sequence of steps
Flowchart and pseudo code –steps and program flow
Translate flow chart/algorithm into instruction using language – assembly, C
Test and debug program

31. Flow chart symbols

32. Flow chart

33. Sequence

34. WHILE-DO

35. IF-THEN-ELSE

36. End of Lecture 14