Elapsed timer not working as expected at 64MHz

[Demon]

Roger, oveur.

[longpole001]

yep there was no elapsed-18_k22

[richard]

seems to me the easiest way to restore correct function for "ticks" when the post scaler is in use is to move the ticks loop inside the post scale loop , no extra vars no extra overhead

ClockCount:
@ RELOAD_TIMER                   ; Reload TIMER1

    T1Post = T1Post + 1
    IF T1Post = T1PS THEN
      T1Post = 0
     Ticks = Ticks + 1
        IF Ticks = 100 THEN
           Ticks = 0
           Seconds = Seconds + 1
           SecondsChanged = 1
           IF Seconds = 60 THEN
              Seconds = 0
              Minutes = Minutes + 1
              MinutesChanged = 1
           ENDIF
           IF Minutes = 60 THEN
              Minutes = 0
              Hours = Hours + 1
              HoursChanged = 1
           ENDIF
           IF Hours = 24 THEN
              Days = Days + 1
              DaysChanged = 1
              Hours = 0
           ENDIF
       ENDIF
    ENDIF
@ INT_RETURN                     ; Restore context and return from interrupt

[Demon]

I can only think that there was a reason why Darrel did it as he did. The dude could probably code this stuff while playing ping pong; the Bruce Lee of PBP and ASM.

There's more than one way to solve a problem, he probably took the one that worked for all PICs (until the K22 series came along). And even that he's solved the problem, it just wasn't widely known. I can only think he had greater concerns on his mind. Can you imagine how much of a headache it must have been tracking the new releases versus his routines? Makes me appreciate and miss him even more.

I now fear the day when Microchip releases a new product line. I love the K22 like I loved the 16F628 and 16F877, I'm not changing unless I'm forced to change.

Shoot, I might even stay on PBP 2.6. LOL

[richard]

it has nothing to do with the k22's its the problem exists whenever the T1PS value is >1 on any chip
its all to do with the way he implemented the post scaling , the loops are inside out . its no bigie to fix . its only apparent if you need to use "ticks" .
imho most of the time using ticks is pointless by the time you process the reading and then display it it's already meaningless and out of date . if you want to time events to such accuracy trigger times need to be allowed for and properly sync'ed , there are much better ways
ps
the k22 interrupt vagaries are a separate issue and unrelated to ticks not being 100th's of a sec

[Demon]

its only apparent if you understand what's going on .

There, fixed it for you. LOL

I never dealt with timer guts before. I always thought pre-scaling and post-scaling were what the fish looked like when my mom prepared them.

Oh and I don't like fish.

Robert

[richard]

you have to toggle your led at the correct place in the loop
the interrupt runs at 4x the speed required (because of high fosc not chip type ) for timing so the post scaler divides it by 4

ClockCount:
@ RELOAD_TIMER ; Reload TIMER1

T1Post = T1Post + 1
Robert toggle your pin here eg latd.0=!latd.0 for 2.5mS
IF T1Post = T1PS THEN
T1Post = 0
Ticks = Ticks + 1
Robert toggle your pin here eg latd.1=!latd.1 for 10mS
IF Ticks = 100 THEN
Ticks = 0
Seconds = Seconds + 1
SecondsChanged = 1
IF Seconds = 60 THEN
Seconds = 0
Minutes = Minutes + 1
MinutesChanged = 1
ENDIF
IF Minutes = 60 THEN
Minutes = 0
Hours = Hours + 1
HoursChanged = 1
ENDIF
IF Hours = 24 THEN
Days = Days + 1
DaysChanged = 1
Hours = 0
ENDIF
ENDIF
ENDIF
@ INT_RETURN ; Restore context and return from interrupt

[Demon]

you have to toggle your led at the correct place in the loop
the interrupt runs at 4x the speed required (because of high fosc not chip type ) for timing so the post scaler divides it by 4

I know that now because I've spent 3 days on this. LOL

But ask me in a week and I won't remember, I'll spend another day running around my tail wondering why I get 4 times too many ticks at 64MHz.

I might eventually remember this long-term, if I do it for weeks. But I have sleep apnea that can't be treated completely, so what I experience during the day doesn't always get stored properly overnight in my sleep. Consider me as obsessive compulsive against my will. I can leave comments about quadruple ticking, but I'll glance over the comment and ignore it until it bites my face for a day or so. LOL

Shoot, my wife gave me $600 a month ago and I totally forgot.

Robert

[Demon]

...imho most of the time using ticks is pointless by the time you process the reading and then display it it's already meaningless and out of date . if you want to time events to such accuracy trigger times need to be allowed for and properly sync'ed , there are much better ways
ps
the k22 interrupt vagaries are a separate issue and unrelated to ticks not being 100th's of a sec

I disagree. This is the first time I have a specialized need for a timer and it requires knowing how long a tick really is. I want to debounce using interrupts, so I press a button, look how long it takes for the contact to close and open again, take an arbitrary average and add maybe 25%, that's my debounce in mSeconds.

I know others use timers in what I consider a more complicated way, I have no clue how a preload value works and can never remember if the timer counts up or down from there (I have a hard time remembering little details like that). To them it's easier, I prefer the elapsed timer approach.

I turn a LED on and off, check the interval on the Saleae probe (I should get a commission every time I typed that), and that's it. Ticks=10mS is stuck in my brain ever since I first saw it on Darrel's include. I just count the ticks until I get my interval.

When you think about it, if we were that concerned with accuracy, we'd program in assembler.

Robert