The basic format of PIC microcontroller programming

　　In order to quickly grasp the basic structure of the PIC microcontroller source program, a typical program structure framework is given here. When creating a source program, first use the pseudo-instruction TITLE to provide the title of the program, then give a general description of the entire program, and use the list pseudo-instruction LIST to specify the microcontroller model and file output format used, and then use the INCLUDE pseudo-instruction to read the definition file provided in MPASM, such as "P16F84 INC", and then define the commonly used resources in the chip, and then give the basic structure framework of the general program. An example is given below.

TITLE "This is..."; Program title
　　; Program description
　　LIST P="16F84", F=1NHX8M
　　;
　　include
　　-config_RC_Qsc & _WDT_0FF…
　　；Resource definition and variable definition
　　STATUS EQU 03
　　FSR EQU 04
　　PORTA EQU 05
　　PORTB EQU 06
　　J EQU 01F
　　K EQU 01E
　　；……………………
　　　　　　ORG 0000 ；
　　　　　　goto MAIN ；Skip interrupt vector
　　　　　　ORG 0004
　　　　　　goto INTSRV ；Subroutine entry address
　　；……………………………………
　　MAIN　　　

　　 　　; Start from 0005H and put the main program
　　　　　　call Initports ; Port initialization
　　　　　　call InitTimers ; Timer initialization
　　　　　　 ...
　　INTSRV ... ; Interrupt service program area
　　SVBRTH... ; Subroutine area
　　　　END ; Program end mark
　　Of course, it can be adjusted according to the actual situation when writing the program. The following is an actual program list, which requires writing data 88H into the 20H unit of the internal EEPROM of PIC16F84, and then reading it out from the 20H unit.
　　LIST P="16F84", F=INHX8M
　　；………………………………
　　STATUS EQU 03 ；Define register
　　EEDATA EQU 08
　　EEADR EQU 09
　　INTCON EQU 0BH
　　EECON1 EQU 88H
　　EECON2 EQU 89H
　　；…………………………
　　RD EQU 0 ；Define bit
　　WR EQU 1
　　RP0 EQU 5
　　GIE EQU 7
　　；…………………………
　　　　　 　 ORG 0
　　　　　 　 GOTO WRSTART
　　；………………………………
　　　　　 　ORG 10H
　　WRSTART ；Start writing operation
　　　　　 　CLRW ；Clear W, make W=0
　　　　　 　BCF STATUS，RP0 ；Select BANK0
　　　　　 　MOVLW 20H
　　　　　 　MOVWF EEADR ；Address→EEADR
　　　　　 　MOVLW 88H
　　　　　 　MOVWF EEDATA ；Write data→
　　　　　　　　　　　　　　　　 ；EEDATA
　　　　　 　BSF STATUS，RP0 ;Select BANK1
　　　　　 　BSF EECON1,2 ;Enable write operation
　　　　　 　BCF INTCON, GIE ;Turn off all interrupts
　　　　　 　MOVLW 0X55
　　　　　 　MOVWF EECON2 ;55H→EECON2
　　　　　 　MOVLW 0XAA
　　　　　 　MOVWF EECON2 ;AAH→EECON2
　　　　　 　BSF EECON1, WR ;Start write operation
　　　　　 　BSF INTCON, GIE ;Restore interrupt
　　RDSTART ;Read operation starts
　　　　　 　BCF STATUS, RP0
　　　　　 　MOVLW 20H
　　　　　 　MOVWF EEADR ;Address→EEADR
　　　　　 　BSF STATUS, RP0
　　　　　 　BSF EECON1, RD ;Start read operation
　　　　　 　BCF STATUS, RP0
　　　　　 　MOVF EEDATA, W ;
　　　　　　　　　　　　　　　　 Read EEPROM data into W
　　END