Working clock example using 32K watch crystal

[malc-c]

' Description : PicBasic Pro program using external 32K watch xtal and Timer1

But 50% of the program is in assembler

[Darrel Taylor]

But 50% of the program is in assembler

Then show him how it's done. (in straight PBP)
This task is worth 2 free 4x20 Parallel LCD's ... shipping outide of US/Canada extra.

In case of multiple responses ... style will prevail.
As judged by Darrel Taylor
Ends 11/10/2010 Midnight Mountain Time

[Archangel]

INCLUDE "DT_INTS-18.pbp" ; Base Interrupt System
INCLUDE "ReEnterPBP-18.pbp" ; Include if using PBP interrupts"

[timc]

The earlier versions I wrote had NO asm but lost almost a minute an hour. To make up for that one could re-tune using TMR1H and TMR1L with a larger value. Problem is every change made to the program would mean spending a few days retuning and it would never be as precise.

So yea I would love to be able to do this without asm in PBP AND be as accurate!

Down the road I intend to join this interrupt sample with a SNTP internet program so I can have a near perfect millisecond low power $60 clock.

Regards
Tim C

[Bruce]

   ' Int handler doesn't mess with any PBP system variables - or lower 15-bits
   ' of TMR1 accumulated time. Uses only 4 instructions to set TMR1H high bit,
   ' increment seconds, clear the interrupt flag bit, save & restore WREG, STATUS,
   ' BSR and return from int handler.
 
@myint                  ; create myint label
   TMR1H.7=1            ' Set TMR1 high bit for 1 second overflows
   seconds = seconds+1  ' Increment seconds
   PIR1.0=0             ' Clear TMR1 int flag
   @ retfie  FAST       ; Return with 'auto restore' of WREG, STATUS and BSR

Should do it.

[malc-c]

Then show him how it's done. (in straight PBP)

I wish --- (I'll remove my tongue from in my cheek now )

[timc]

Thank you Bruce
Smaller, tighter, yet perfect speed. Started the clock last night with your change and so far the PIC18F452 has not gained or lost one second.
Tim C

[Acetronics2]

Hi,

I didn't see that one :
http://www.pbpgroup.com/modules/wfse...hp?articleid=8

did I miss something ???

Alain

[timc]

Alain,
Darrel's great example uses one crystal mine uses 2. And oh if something is sitting there soldered to the dev board and you don't have code to see if it works!!

[Acetronics2]

Alain,
Darrel's great example uses one crystal mine uses 2. And oh if something is sitting there soldered to the dev board and you don't have code to see if it works!!

Hi, Timc

Lol ... I didn't remember I had modified Darrel's code to use a 32 Khz Xtal ...

and thought it was already done in the original release ...

Here it is.

Alain