1. Assembly Language Programming for PIC

12. Control Directives #DEFINE Exchange one part of text for another Syntax: #define<text> [<another text>] Example: #define turned_on 1 #define turned_off 0

13. Control Directives cont… #INCLUDE Include an additional file in a program Syntax: #include <file_name> #include &quot;file_name&quot; Example: #include <regs.h> #include &quot;subprog.asm&quot;

14. Control Directives cont… EQU Defining assembler constant Syntax: <name_constant> equ <value> Example: five equ 5 six equ 6 seven equ 7

19. Control Directives cont… ORG Defines an address from which the program is stored in  C memory Syntax: <label>org<value> Example: Start org 0×00 movlw 0xFF movwf PORTB

20. Control Directives cont… END End of program Syntax: End Example: . . movlw 0xFF movwf PORTB end

23. A Simple PIC Application Block diagram

24. A Simple PIC Application cont… Circuit diagram

25. A Simple PIC Application cont… Flowchart

26. A Simple PIC Application cont… Assembly program

27. Assembling & Linking a PIC Program Editor Program Editor Assembler Program Linker Program Download to PIC’s ROM myfile.asm myfile.o myfile.err .lib additional library files .o additional object files .lkr linker script files myfile.out myfile.cod myfile.hex myfile.map myfile.lst

29. Flowchart

34. Example PortB = 8-bit output RA0, RA1 = input

35. Example

36. Example

38. Example

39. Example LOC OBJECT CODE LINE SOURCE TEXT VALUE 00000006 00001 PORTB EQU 06H ;PortB data register 00000010 00002 COUNT EQU 10H ;GPR register 00000011 00003 MYREG EQU 11H 00004 00005 ORG 0H 0000 3000 00006 movlw B'00000000' 0001 0066 00007 tris PORTB 00008 0002 0190 00009 CLRF COUNT ;COUNT = 0 0003 2??? 00010 BACK CALL DISPLAY 0004 2??? 00011 GOTO BACK 00012 00013 ;increase value & send it to PORTB subroutine 0005 0A90 00014 DISPLAY INCF COUNT,F ;count = count + 1 0006 0810 00015 MOVF COUNT,W 0007 0086 00016 MOVWF PORTB 0008 2??? 00017 CALL DELAY 0009 0008 00018 RETURN ;return to caller 00019

40. Example 00020 ;delay subroutine 00021 ORG 30H ;put delay at address 30H 0030 30FF 00022 DELAY MOVLW 0xFF ;WREG = 255 0031 0091 00023 MOVWF MYREG 0032 0000 00024 AGAIN NOP ;no operation wastes clock cycles 0033 0000 00025 NOP 0034 0000 00026 NOP 0035 0B91 00027 DECFSZ MYREG,F ;decrease until MYREG becomes 0 0036 2??? 00028 GOTO AGAIN ;repeat decrement process 0037 0008 00029 RETURN ;return to caller 00030 END 13-bit Before any CALL 1 2 3 4 0004 13-bit After CALL DISPLAY 1 2 3 4 0004 0009 13-bit After CALL DELAY 1 2 3 4 0004 13-bit After DELAY RETURN 1 2 3 4 13-bit After DISLAY RETURN 1 2 3 4

48. Execution Time

51. Program Data Table cont…

52. Program Data Table cont…

53. Program Data Table cont…

55. Exercise