trouble passing variables

GrantmcF

Still having trouble passing variable between cogs. In the attached code I'm trying to start a cog, have it run for 4 min then set a global variable as a flag for a later decision. The problems I'm having is that I can never get the flag set and the 240 sec timer doesn't always work. Any help is appreciated.

Duane Degn

Change

Pub Prewet(Pre_wet_done2)
repeat 240                        'Repeat for 240 times = 4 minutes because of 1 second wait    
  Dira[13..15] :=1             'Sets direction of pins 13-15 to output
  outa[13..15] :=0             'Sets pin 13 high and pins 14 and 15 low
  waitcnt(clkfreq + cnt)          'Wait 1 second
Pre_wet_done2 := 1                'Set status of Pre_wet_done 

 

To:

Pub Prewet(Pre_wet_done2)
repeat 240                        'Repeat for 240 times = 4 minutes because of 1 second wait    
  Dira[13..15] :=1             'Sets direction of pins 13-15 to output
  outa[13..15] :=0             'Sets pin 13 high and pins 14 and 15 low
  waitcnt(clkfreq + cnt)          'Wait 1 second
[COLOR=#ff0000]byte[Pre_wet_done2] [/COLOR]:= 1                'Set status of Pre_wet_done 

Alternatively, you can just use:

Pub Prewet(Pre_wet_done2)
repeat 240                        'Repeat for 240 times = 4 minutes because of 1 second wait    
  Dira[13..15] :=1             'Sets direction of pins 13-15 to output
  outa[13..15] :=0             'Sets pin 13 high and pins 14 and 15 low
  waitcnt(clkfreq + cnt)          'Wait 1 second
[COLOR=#ff0000]Pre_wet_done [/COLOR]:= 1                'Set status of Pre_wet_done 

Since all cogs within one object have access to all the global variables.

I suppose it doesn't hurt to keep setting the direction and output state of the pins but you could do these just once at the beginning of the method and then just loop your waitcnt only. Also the current method of waiting 240 seconds will be little off since it doesn't take into account the loop overhead. I think the waitcnt section of the Propeller manual has instructions on how to have more accurate wait times.

JonnyMac

Here's how I'd do it:

pub pre_wet(seconds, flagpntr) | t

  dira[13..15] := %111
  outa[13..15] := %100

  long[flagpntr] := false

  t := cnt
  repeat seconds
    waitcnt(t += clkfreq)

  long[flagpntr] := true
  cogstop(cogid)

Call it like this using the address of a long that is in the global variable declarations:

cognew(pre_wet(240, @wetdone), @stack)

I think passing the timing allows you to forget about the internals of this method once it works; your main code can adjust timing.

StefanL38

Hi GrantmcF,

I want to point again onto

  DirA[13..15] := %111

instead of

  DirA[13..15] := 1

if you want to set more than one pin to value 1
you need to assign a value where every bit is set to 1
easiest way to do this is to use binary numbers through using the "%" in front of the digits

  DirA[13..15] := %111

is the same as

  DirA[13..15] := 7

best regards
Stefan

GrantmcF

I figured out the problem. It wasn't in the variable passing. It was the repeat loop continually resetting the new cog. The count never finished, so the variable never got a chance to be passed. Another flag and state check before the cog start lets it bypass the cog start if it is already running. Thanks for the help guys.