Microchip AN615

[shahidali55]

Thanks Acetronics, i'll try that out.
But sayzer, i want to use a PIC16C54A. It does not have TMR0 interrupt.
I have to mux 4 displays, check 4 buttons and keep accurate time.
How can i keep track of time without the interrupt???
Is there a way to keep time accurately without using hardware interrupts and do the rest of the stuff in PBP???
I have made a clock using a F84 and TMR0 interrupt...
Now i want to do the same thing without the TMR0 interrupt in PBP...

[Acetronics2]

Hi, Shahid

You're so right not to move to other Pics ... I tried some times ago from a 16C54 to a 16F84 ... ( was a " Berliner clock " !!! )

Result was not that !!! The differences between program counters and adressing make things really tricky ... possible to do, but very high upon my Pic's knowledge !!!

One thing about your program, I didn't tell you anything about PM and AM ...

if you want to use the alarm function, you'll have to add a flag for that ... look carefully at the digit overflows section : there are lines where hours units are cleared after hours tenths overflow : just toggle your flag here !!!
Of course, add a flag check to digits check for alarm raising ...

Alain

[sayzer]

Ali,

I guess you are targeting a low cost solution by selecting PIC16C54.

Am I right?

Edit: Ok. I just found this in your other post.
"I dont want to spend too much cash on erasable PICs cause once i give away the projects the IC will never be erased again..."


In this case, are there any other factors that make you use this chip?


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[shahidali55]

Ya i need to make these circuits at a low cost...
Actually i am facing a major problem with chips that do not have a TMR0 interrupt (12C508A).
All the devices need to have a basic accurate clock running in the background.
How can a implement a hour minute clock on PICs which do not have the TMR0 interrupt (but have timer0) and do other stuff also without much interference from the clock routine?
Is there a way i can do it in PICBASIC PRO ???

[mister_e]

I never found a PIC with a accurate internal clock. It shift at least with temperature.

You can still skip the interrupt and use MPASM Stopwatch (or else) to trim your program timing using a simple loop.

[Acetronics2]

Hi, Steve

IF you want a program for a real time clock ( trimmable ) with a lonesome 12C50x ...

I Have !!!

hi,Hi ...

Alain

OK, there's a trick somewhere ... but it works !!!

PS: Even OTP device programs can be modified ( "1"s can be overwritten by "0"s ) ... do not repeat it !!!

[shahidali55]

Can anyone give me a piece of code that can do the time keeping in PICBASIC without using interrupts ? ? ? Even if it just detects the roll-over and polls a flag, it'll do...
I wrote a PICBASIC code for a digital clock without interrupts.
No matter what prescaller i select, the clock runs 3 times slower.
I check the timer roughly every 50 instructions for a roll-over (By checking the MSB). . .
When i enable interrupts for the same code with same prescaler, it works fine.