Code Problems with 16F684

[Ryan7777]

I guess I was thinking that 1000 mS was equal to 1 second and 3000 mS was equal to 3 seconds in PIC time. turns out I was wrong, tweaked my pauses a little and got it to work right.
However, still having serial issues, unimportant now, But I suspect if I were using a better OSC it would clear up. I have a cap across the rails right at the pic but I may tack on a smaller one right across the power pins to see if that helps.

While I'm using up a post I might as well ask another question. I getting ready to do something with serial again, and I want to use a "two's complement addition" error checking routine and I'm a bit afraid of the math involved. I guess an example of some code could help, or if someone could explain how to add three bytes with no carries or how to discard the overflow bits? To explain it in terms of (A+B+C) ? discard some things = 0 using actual PBP operators would be the most helpful. Or if someone has a ready to use routine? or is there something easier?


Thanks as always ahead of time.

[cncmachineguy]

I don't know about your current question, but I think I can shead some light on you solution. You have OSC = 8 for an 8meg clock, but the pic you are using defaults to 4 meg. To use 8 you need to set up OSCCON reg for 8 meg clock. The DEFINE OSC just tells PBP how fast you INTEND to run, so it is able to calculate the delays for your pause. I am guessing your pauses were taking twice as long? so 1000 = 2 sec and 3000 = 6 sec?

This will also affect your serial issues

[Dave]

Ryan7777, I can't help but notice that you are missing a compare value in the last statement:
IF aTOd < 45 AND aTOd ??????? THEN DutyCycle1 = 1023
ENDIF

I think I would write this routine it as follows to save you some cycles:

SELECT CASE aTOd
CASE < 94
DutyCycle1 = 10
CASE < 187
DutyCycle1 = 10
CASE < 280
DutyCycle1 = 30
CASE < 373
DutyCycle1 = 50
CASE < 466
DutyCycle1 = 70
CASE < 559
DutyCycle1 = 90
CASE < 652
DutyCycle1 = 110
CASE < 745
DutyCycle1 = 130
CASE < 838
DutyCycle1 = 150
CASE < 931
DutyCycle1 = 170
CASE <= 1023
DutyCycle1 = 200
END SELECT

That should save you some cpu cycles...

Dave Purola,
N8NTA

[Ryan7777]

Thanks for your replies. I had always assumed that the 16F68Xs just defaulted to 8 instead of 4 Mhz. I'll OSCTUNE it to 8, as you said, it seems like everything is timing out to be twice as long. That explains a lot, Thanks! And yeah, I'll re-write it for select case for the end version, I was still hashing it out and ended up with rough code trying to figure out the timing issue. Now that I have that figured out, and If i can use serout to debug my dimming feature, I can tighten it all up.

Thanks again to the both of you, You guys are awesome.

Ryan

[mackrackit]

i'll osctune it to 8

nope!!!

DEFINE OSC 8              
OSCCON = %01110000