Buying PICkit-2

Learn about PIC12F629

• PIC12F629 Data Sheet (.pdf 4,926KB)
• Instruction Set for PIC12F629
• blank12F629.asm template
• Notepad++ or VS Code
• PIC12F629.asm Chip as a “D” flip flop
• Library of Sub-routines “Cut and Paste”
• Library of routines: A-E E-P P-Z

This program will produce a tone from the piezo of approx 130Hz to show how fast the EEPROM can be accessed.
However the EEPROM only has a life of 1,000,000 cycles and if the project is activated for a period of time, EEPROM location 127 will fail after about 1 hour. That’s why we have selected the last location in EEPROM, as it will rarely be used for anything else.

Here is the code:

• EEPROMWrite.asm
• EEPROMWrite.hex

EEPROM Write for PIC12F509

;EEPROMwrite.asm
;How fast is EEPROM write?  Use this program to listen to the
;frequency that is produced with 2 EEPROM writes in each cycle.
;Our PIC12F629 produced a frequency of 133Hz
;  11-3-2010

;*******************************
;
;       --+------------ +5v
;         |
;         |
;         |Vdd ---v---
;         +---|1   Gnd|-------------+
;             |       |             |
;          ---|GP5 GP0|--           |
;             |       |             |
;            -|GP4 GP1|--       |
;             |       |     |  |    |
;           --|GP3 GP2|-----|\[\]|----+
;             -------       |  |    |
;            PIC12F629      piezo   |
;                                   |
;                                   |
;    -------------------------------+-- 0v

 list   p=12F629
    radix   dec
    include "p12f629.inc"

    errorlevel  -302    ; Don't complain about BANK 1 Registers during assembly

    __CONFIG    _MCLRE_OFF & _CP_OFF
                     & _WDT_OFF & _INTRC_OSC_NOCLKOUT  ;Internal osc.

;_MCLRE_OFF  - master clear must be off for gp3 to work as input pin

;****************************************************************
; variables - names and files
;****************************************************************


temp1       equ 20h


;****************************************************************
;Equates
;****************************************************************
status      equ 0x03
rp1     equ 0x06
rp0     equ 0x05
gpio        equ 0x05


status      equ 03h
option_reg      equ 81h


        ; bits on gpio

pin7        equ 0   ;GP0
pin6        equ 1   ;GP1
pin5        equ 2   ;GP2  Piezo between pin and 0v rail
pin4        equ 3   ;GP3
pin3        equ 4   ;GP4
pin2        equ 5   ;GP5


        ;bits

rp0     equ 5   ;bit 5 of the status register



;****************************************************************
;Beginning of program
;****************************************************************
    org 0x00
    nop
    nop
    nop
    nop
    nop
SetUp   bsf status, rp0     ;Bank 1
        movlw   b'11111000' ;Set TRIS  GP2 out
    movwf   TRISIO          ;
    bcf status, rp0     ;bank 0
    movlw       07h                 ;turn off Comparator ports
            movwf       CMCON           ;must be placed in bank 0
    clrf    gpio            ;Clear gpio of junk
    goto    Main


;****************************************************************
;* Sub Routines             *
;****************************************************************

    ;read takes the value 0 or 4 from EEPROM location 127 and puts it in w

read
    movlw   .127
    bsf status,rp0
    movwf   EEADR
    bsf EECON1,0     ;starts EEPROM read operation. Result stored in EEDATA
    movf    EEDATA,w     ;move read data into w
    bcf status,rp0
    movwf   temp1        ;temp1 has the value 0 or 4 to activate piezo on GP2
    retlw   00



write
    bsf status,rp0  ;select bank1
    movwf   EEDATA
    bcf status,rp0  ;select bank0
    movlw   .127
    bsf status,rp0  ;select bank1
    movwf   EEADR
    bsf eecon1,wren ;enable write
    movlw   55h         ;unlock codes
    movwf   eecon2
    movlw   0aah
    movwf   eecon2
    bsf eecon1,wr   ;write begins
    bcf status,rp0  ;select bank0
writeA  btfss   pir1,eeif   ;wait for write to complete
    goto    writeA
    bcf pir1,eeif
    bsf status,rp0  ;select bank1
    bcf eecon1,wren ;disable other writes
    bcf status,rp0  ;select bank0
    retlw   00


;****************************************************************
;* Main                     *
;****************************************************************

Main    movlw   b'00000100'
M1  call    write
    call    read
    movf    temp1,w
    movwf   gpio
    movlw   b'00000000'
    call    write
    call    read
    movf    temp1,w
    movwf   gpio
    goto    Main


;***************************************************************
;*EEPROM     location 127 will be used by the program
;****************************************************************

    org     2100h


    end