I2C with 16F628A mystery

[lilimike]

The chip is enclosed into a sealed device and the only thing exposed are the 4 pads for power and I2C. With trial and error... and trial and error over trial and error I managed to get what I need working. I know my program doesn't have much style but for now it does what it is supposed to do.

The process of my program is as follow:
When I press the switch I need to read address $04 and if it is > 5 it will flash the OK LED the number of the value found and then quit. If it is not greater than 5 then I want to set values $01,$01,$01,$3c,$3c,$3c,$3c,$3c,$3c,$08,$08,$08,$2 1,$21,$21,$FF all over.
I don't understand why I just write once and the chip gets updated all over but it works.

This device is hooked up to another device that will update the chip daily by setting address $04, $05, $06 to -1 each day.

I am definitely going to order some chips and test on breadboard until I get a good understanding of this.
In the mean time this is my working code:

@ __config _INTOSC_OSC_NOCLKOUT & _WDT_OFF & _MCLRE_ON & _LVP_OFF & _CP_OFF
clear
DEFINE OSC 4
TRISB = %00001000           
CMCON = 7                   ; Disable comparator
OPTION_REG = 0


SWSTAT      var byte
Dat         VAR byte
I           var byte
I2CAddr     Var word
I2CDevice   var byte
D1          var PORTA.2     ; Cartrige white wire
D2          VAR PORTA.3     ; Cartrage blue wire
Activate    var PORTB.2     ; select between reset=1 normal=0
GO          VAR PORTB.3     ; Start switch
OK          VAR PORTB.4     ; Green LED
NOTOK       var PORTB.5     ; Red LED

activate = 0                ; Normal operation
ok = 0                      ; Green LED off
notok = 0                   ; Red LED off

goto swstatus

Start:

;--------make sure reset is needed-----------
activate = 1                ; get ready to reset
swstat = 0                  ; reset switch debounce
pause 50                    ; give time or relay contact

i2cdevice = $A1
i2caddr = 3
i2cread d1,d2,i2cdevice,i2caddr.lowbyte,[dat]
pause 10

if dat > 5 then
    for I = 1 to dat
        ok=1: pause 500:ok = 0:pause 500
    next
    activate = 0                    ;------Resume normal operation
    goto SwStatus
else

    ok = 1: pause 3000: ok = 0  ; Green LED on for 3 seconds
    pause 5000
    I2CAddr = $0
    I2CDevice = $A0

    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$01]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$01]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$01]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$3c]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$3c]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$3c]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$3c]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$3c]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$3c]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$08]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$08]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$08]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$21]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$21]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$21]:i2caddr = i2caddr + 1:pause 10
    i2cwrite d1,d2,i2cdevice,i2caddr.lowbyte,[$ff]:pause 10

;---------------------make sure data was written-------------------------
    i2cdevice = $A1
    i2caddr = 4
    i2cread d1,d2,i2cdevice,i2caddr.lowbyte,[dat]
    pause 10
    activate = 0                ;------Resume normal operation
    if dat = $3c then           ;------all is good, flash green LED
        for I = 1 to 10
            toggle ok
        pause 500
        next
        ok = 0
    else                        ;------Something wrong, flash red LED
        for I = 1 to 10
            toggle notok
            pause 500   
        next
        notok = 0
    endif
endif

SwStatus:
if go = 0 then debounce
swstat = 0
goto SWstatus

debounce:
swstat = swstat + 1
pause 10
if swstat = 150 then start
goto swstatus

END

Thank you for your help.

Mike

[mackrackit]

Have you seen/tried this?
http://www.picbasic.co.uk/forum/cont...cation-routine

[lilimike]

Hi Dave,

I went a little too fast in my project, when I thought my circuit was good I built the PCB and dismantled my breadboard and its only after I saw this.

But thanks for the info

Mike