Code help please timer with 16f84a

[pasicr]

push darkroom timer german

Hi,
I send message before with explain my problem. I whill try again,
I use 4 digit countdown timer with pic 16f84a. The output is reley. I control heating element who work on 220v ac.
I need heating only untill countdown. The reley must be OFF before and after countdown. In my case when timer countdown 0000 reley going to OFF. This is OK. But when I reset counter reley going to ON position before I push start button to countdown.
Please some one help me.
The original code is for sound alarm dark room timer.
Regards

 

[Gorgon]

Hello,
I've just skimmed through the code, and I can't see that you initialize portb in the init routine. From what I saw, this is the old code from Stan Ockers darkroom timer.
I did a job on another project based on this code in April. I remember the guy making this had a problem with the watchdog timeout during writing to the eeprom.

You don't say anything about the bits used, but I assume you use portb.4 for the relay. This output is in conflict with the anode driver for the display. Since I dont know your hardware I can't tell if this will make a problem for you.

Please post some more info on your timer hardware.

TOK

 

[pasicr]

Hi Gordon,
My hadware is based on attached schematic. Diferent is, I use RB4 for drive reley via cuple of resistors and two transistor, and RB5 I dont use.
If you need more info please mail me,
regards

 

[Gorgon]

You could post a schematic for the relay driver, or describe it properly. Does it activate the relay on low or high output?

TOK

 

[pasicr]

Hi,
I activate relay with logic "1" or high output (BSF PORTB, RB4). The complete schematic for driver I have on my PC at work, but I send you attached picture, this is very similar to my driver,
regards