prof. jorge a. ramón introducción a microcontroladores
TRANSCRIPT
Microprocessor VS Microcontroller
1. CISC Architecture
2. Many pins
3. Many instructions
4. External devices needed for operation (memory, I/O, etc)
1. RISC Architecture
2. Fewer pins
3. Fewer instructions
4. No external devices needed for operation (memory, I/O, etc are already built into IC)
Microchip PIC16F84 Microcontroller Outline
8 bits
8 bits5 bits
35 instructions64 bytes
68 bytes
1K x 14
Clock / Instruction Cycle
Q1 Instruction Fetch Q2 Instruction Decode Q3 Execute Q4 Write Back
Pipelining: each instruction is executed in one cycle.
Two cycles for JUMP and CALL instructions .
Instruction Set Summary
Byte OrientedBit OrientedLiteralControl Operations
Only 35 instructions!!
Impressive!!!
Programming Example
Setting PORTB as Output
1. Set RP0 in Status Register to switch to BANK1. This allows access to TRISB.
2. Write 0x00 into TRISB.
3. Clear RP0 in Status Register to switch to BANK0. This allows access to PORTB.
Programming Example
Setting PORTB as Output
1. BSF STATUS, RP0
2. MOVLW 0x00
3. MOVWF TRISB
4. BCF STATUS, RP0
5. MOVLW 0xFF
6. MOVWF PORTB
Assembly Programming
Steps to write some code
1. Tell the assembler which MPU you are using.
2. Include the header file.
3. Set PC to 0
4. Write some code
5. Keep an endless loop.
6. Use the end directive.