1. By Muhammad Ali Mazidi, Rolin McKinlay, Danny Causey
Ch. 2- Assembly Lang - PIC
The PIC Microcontroller and Embedded Systems:  Using Assembly and C for PIC18
By Muhammad Ali Mazidi, Rolin McKinlay, Danny Causey

2. http://microdigitaled.com/PIC/Software/PIC_tools.htm Install MPLAB
Install C18
Read tutorials from -

3. Finish!!!?
Now work at home n learn – based on the concepts of Intel 8086’s Assembly Language =======

4. Working Register

5. Only one!
WREG – Working REGister is same as Accumulator in other microprocessors
WREG us used for all arithmetic and logic instructions

6. MOVLW instruction MOVLW  move 8-bit data into the WREG reg.
MOVLW k
 Move literal value of k into WREG
L  Literally – a number must be used
Similar to immediate value of 8086’s assembly language
MOVLW 25H
 Move value 25H into WREG

7. MOVLW ‘L’ stands for literal
Immediate value concept of other microprocessor
‘W’ for WREG
MOVLW  move a literal value to WREG reg.

8. ADDLW

9. ADDLW
Add ‘k’ to register WREG
Put the result back in the WREG

10. WREG & ALU using literal value

11. MOVLW 5h
MOVLW 05h
MOVLW ;in binary
Moving a value larger than 255 (FF in hex) into the WREG register will truncate the upper byte and cause a warning in the .err file

12. 2.2: File Register File register == data RAM == data memory
== (general-purpose-reg. + special-function-reg.)
Data memory space is different from program (code) memory

13. Data RAM == special-function-reg + general-purpose-reg
Special-fn.reg. [SFR] for specific functions, e.g.,
ALU status
Timers
Serial communications
I/O ports
ADC
Etc.

14. SFR…
Function of each SFR is fixed by the CPU designer at the time of the design – as it is used for control of the microcontroller or peripheral
8-bit registers
No. of locations in the file reg.?
7 to over a hundred
more timers in a PIC, the more SFR reg. it has

15. Data RAM == special-function-reg + general-purpose-reg
GPR / RAM
Used for data storage and scratch pad
8 bits wide
The space that is not allocated for SFRs – typically is sued for GPR

16. File reg. size [in bytes]
PIC File register = SFR + GPR
PIC12F bytes
PIC16…
PIC18F

17. GPR RAM vs. EEPROM GPR – internal data storage, used by the CPU
EEPROM – as an add-on memory, can add externally to the chip

18. File register & access bank in PIC18
PIC18 family can have a max of 4096 (4k = 212) bytes
So, address range of the file reg. = 000h ~ FFFh
File reg. is divided into 256-byte banks
So, 4069/256 = 16 banks
At least one bank for the file reg. – called access bank

19. 256-byte access bank  two 128 bytes sections = GPR & SFR
The 128 bytes – from locations 00H to 7FH – as General-purpose reg.
used for read/write storage
Scratch pad
For storing data & parameters by PIC18 programmers & C compilers
The other 128 bytes – from locations F80H to FFFH – as special-function reg.

20. So far for PIC
MOVLW
ADDLW
Literal
WREG

21. 2.3: Using instructions with the default access bank
MOVWF  it tells the CPU to move (in reality, copy) the source reg. of WREG – to a destination in the file reg. (F)
So, the location (new) in file reg. will have the same value as reg. WREG.
F – file reg. – stands for a location in the file reg.
W – WREG

22. Move to SFR MOVWF PORTA MOVLW 55H ;WREG = 55H
; move the contents of WREG  into SFR reg. called PORTA
MOVLW 55H ;WREG = 55H
MOVWF PORTB ;copy WREG to Port-B
MOVWF PORTC ;copy WREG to Port-C .
PortB, PortC, and PortD are part of the special function reg.
They can be connected to the I/O pins of the PIC mic.

23. Q: Can literal values directly into SFR?
Move to GPR
Move [copy] contents of WREG GPR/RAM
MOVLW 99H ;WREG=99H
MOVWF 0H
;move [copy] WREG contents to location 0h …
Cant move literal [immediate] values directly into the general-purpose RAM locations in the PIC18.
They must be moved there via WREG.
Q: Can literal values directly into SFR?

24. ADDWF ADDWF fileReg, D ; =[WREG] + [fileReg] Sources:
ADDLW 15H ; =15h + [WREG]
ADDWF fileReg, D ; =[WREG] + [fileReg]
Sources:
Content of WREG
fileReg: Content of file register (special or general)
Destination: D  indicates destination bit
If D = 0, destination of the result is WREG, or
If D = 1, destination is file register