trying to relearn PASM

TreeLab

Greetings All;
After several years away, I am trying to code a PASM routine to control a pulse. And with advancing age, I am having limited success.
The program is to output a pulse (pin 0) followed by a controlled delay. When this delay is hard-coded into a PASM variable (OffDuration) the program works as expected, all the time. WHen I try to have the PASM code rdlong the delay count from hub memory (variable dT), it gives sporadic pulses. I have tested to see if the OffDuration is zero and toggle Pin1 to show this : this works fine for hard-coded values, but when I rdlong the dT=zero from hub, it doesn't see it as zero, and Pin1 is unaffected.

If behaves badly even if I only do the rdlong once, before the repetition loop is entered, so I don't think the time to synch the cog is the issue.

Obviously I am missing something pretty basic here. I would very much appreciate any help that folks can provide.
Cheers!

CON
  _clkmode   = xtal1 + pll16x                           
  _xinfreq   = 5_000_000                                'Set to standard clock mode and frequency (80 MHz)

VAR
  long  dT
pub start(ptr)

  cognew(@PulseEntry, @dT)

pub Main 
  dira~~
  dT := 40*80
  start(@dT)

  repeat
  
dat
                        org     0

PulseEntry              mov     temp, par
                        rdlong  OffDuration, temp                               ' read from hub the off time in clock cycles
                        mov     dira, dira__                                    ' set up the dira register

:PulseLoop              cmp     OffDuration, #0      wz                         ' set the Z flag if off-time=0

            if_z        mov     outa, #2                                        ' DEBUG : use pin 1 as an indicator of the z flag  

            if_nz       mov     outa, #1                                        ' set the pin high if the off-time is >0  
                        mov     Time, cnt                                       
                        add     Time, OnDuration
            if_nz       waitcnt Time, #0                                        ' only delay if the pin was set high (ie off-time>0)
                        mov     outa, #0                                        ' set the pin low, regardless

                        mov     Time, cnt
                        add     Time, OffDuration

                        ' rdlong  OffDuration, temp                             ' get value of off-time to be used for next cycle
            if_nz       waitcnt Time, #0                                        ' do the wait iff the off time was >0
                        jmp     #:PulseLoop

temp                    long    0
OffDuration             long    80*90
OnDuration              long    80*10
Time                    long    0
zero                    long    0
dira__                  long    |< 0 + |<1                                      ' pin 0 is the one to use, pin 1 is for debug tracking of Z flag

Phil Pilgrim (PhiPi)

-Phil

tonyp12

VAR
  long  dT
pub start(ptr)

  cognew(@PulseEntry, @dT)

pub Main 
  dira~~
  dT := 40*80
  start(@dT)
 repeat

I'm pretty sure you have to put {pub start} after {pub Main}, as the code will go in order and run pub start first and then main will run it again.
And you passing along a prt in start, but are not using it so change it to:
pub start(ptr)
cognew(@PulseEntry, ptr)

TreeLab

tonyp12 : absolutely! Thank you very much! The ptr was just to do debugging, but the code sequence was the ticket. Forgot all about that.

It's not the loss of memory that gets you, it is the not-knowing that you have forgotten ...

Thanks again!