Hello again,

I guess I will be well known to this list because of my multiple
questions addressed to you. I have now over 1 year experience with
PIC's, but still have a lot of questions...
This one regards a simple issue (as it is the case with many of my
questions): I am trying to make a routine to keep count of the seconds.
I have a 20MHz PIC, and need one second period. I use Timer0, with no
prescaler and have inspired myself after the "zero-error" procedure of
Roman Black. My code is the following:

        if (T0IF) {
                if (bres_mid == 0) {
                        bres_hi--;
//some counters - is there a problem with them here ?
                        if (!(serialcount--))
                                serialflag=1;
                        if (txcount)
                                txcount--;
                        if (waitcount)
                                waitcount--;
                }
/////////////////////////////////
                bres_mid--;
                if (bres_mid == 0 && bres_hi == 0) {    //one second has
passed
                        bres_hi = BRES_HI;
                        bres_mid = BRES_MID;
                        bres_lo += BRES_LO;
                        #asm
                        btfsc   _STATUS, 0
                        incf    _bres_mid
                        #endasm
//code executed each second - incrementing some time registers
                }
        }

Now, my time period is bigger than 1 second as in 10 minutes, it delays
about 20 seconds. Where is the problem ? With the code in (bres_mid ==
0) or is the code after the second period too large ? The counters in
(bres_mid == 0) are for some routines needing a period smaller than one
second...
I'm sorry if this seems too simple for you, but I'm trying to understand
what is wrong here.
Thank you !

Lucian

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