TMR0 stops working

[Archangel]

Hi shahidali55,
On the perfboard I would probably run a buss wire lengthwise under the pic and from each pin I would add .o1uf or even .001 uf capacitors to the buss wire which is hooked up to ground, I think you are getting RF into the chip from the outputs, RF is funny, it sort of crawls on the outside of conductors and does funny things. AS for things like cellphone chargers emitting RF I guess it depends upon which country's emission standards they meet or fail to meet. You might try using 2 bypass caps, 1 from each leg of the Mains power to ground right at the outlet. Ferrite beads are useful to trap RFI on wires on the circuit board. Be sure they are made for that high of a voltage,otherwise they pop like firecrackers Some links on RFI:

http://www.edn.com/archives/1995/010595/01df1.htm
http://www.eham.net/articles/12139

[shahidali55]

16F628A has been running stable for 10 days now.(Tried doing all sorts of things to make it reset, but its immunity is really good).
So i guess the only solution is to stick with the 16F628A . . .

[shahidali55]

My problem is still very much alive.
I had turned off the clock for over a month.
Now the clock "locks up" within 48 hours.
It has locked up twice at 7 hours , 14 minutes (7:14).
The mux routine works fine but the ISR just stops updating timing registers.
(The varibles that handle this are bres_hi ,bres_mid ,bres_lo.)
(uC is 16F628A and TMR0 used ot keep time)

[Darrel Taylor]

I'm still thinking it's related to voltage.

The device is being powered by 3.6V
But the 16F84A is only specified to work down to 4.5V

In post #3 you said the datasheet specifies 2.0V
But that's only for the 16LF84A

Edit: Doh! You're using the 628 now. Nevermind.
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[Darrel Taylor]

shahidali55,

Do you have an updated program?
I tried to compile the program from post#1, but it has too many errors.

It also has the pushbuttons on the same pins as the segments, and ASM opcodes in column 1.
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[shahidali55]

Hello Darrel,
As you suggested in post 2, the battery now charges from output from the 5v regulator (through a diode and a 2.2k resistor). The voltage at the PIC never rises above 4.6v. I tested this system with a 20v DC supply and the voltage at the pic pins is still at 4.63 volts (after 48 hours of running).

I have attached a copy of the file with the required include (Instant interrupts) as a zip archive.
The pushbuttons are not a concern now since the primary function of the device itself
(i.e. keeping time) is not met.

Is ASM opcodes in column 1 bad ?

[Darrel Taylor]

I have attached a copy of the file with the required include (Instant interrupts) as a zip archive.

I don't understand why you've modified DT_INTS-14 like that. There's no need.
I also don't like modified versions being posted on the Internet. Somebody will download it, it won't work, and then they'll blame me.

Is ASM opcodes in column 1 bad ?

Yes! Very BAD!
ONLY Labels can go in the first column of ASM code.
This applies to lines using the @ sign too. There must be a space after the @. (unless it's a label)

With opcodes in column 1, the program won't compile. So that can't be the program you are currently running in the chip.

DT