Need a recommendation

CannibalRobotics · 2008-10-03 16:53

I have been unable to get my head wrapped around where a variable lives in the prop and how it is most efficiently referenced/modified from multiple cogs. Can someone recommend a good tech note on this aspect of the architecture/language.

Thanks,
Jim-

Paul Baker · 2008-10-03 17:39

Hi Jim,
You need to be a little more specific with your request, are you talking about intraobject or interobject, are you talking about assembly to assembly, assembly to spin, or spin to spin?

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Paul Baker
Propeller Applications Engineer

Parallax, Inc.

StefanL38 · 2008-10-03 18:12

Hello Jim.

as long as all cogs are started by cognew from the SAME *.SPIN-File
you can access them simply by the name of the variable
here is a demo which shows that

CON
  _clkmode = xtal1 + pll16x
  _xinfreq = 5_000_000

  
VAR
  long heart_stack[noparse][[/noparse] 20]
  long CogStack1[noparse][[/noparse] 20]
  long CogStack2[noparse][[/noparse] 20]
  
  long MyTestVar

OBJ
  'heart : "heartbeat" little object from the obex making an LED blink so i can see Prop is working
  debug : "FullDuplexSerial"


PUB Main
'the FIRST PUB-Method inside a spinfile is ALWAYS the startpoint where the program starts to run
  'heart.Start(27, 200)
  debug.start(31, 30, 0, 9600)
  
  MyTestVar := 100
  debug.str(string("Start MyTestVar="))
  debug.dec(MyTestVar)
  debug.Tx(13)

  cognew(M1,@CogStack1)
  cognew(M2,@CogStack2)
  
  repeat
    waitcnt(clkfreq + cnt)
    debug.str(string("MyTestVar="))
    debug.dec(MyTestVar)
    debug.Tx(13)



PUB M1
  repeat
    waitcnt(ClkFreq * 3 + cnt)
    MyTestVar := 1


PUB M2
  repeat
    waitcnt(ClkFreq * 5 + cnt)
    MyTestVar := 2

if you want to access variables ACROSS different objects
define the variables in your top-object-file
and pass the ADRESS of the variables by using the "@"-operator (the adress-operator

VAR
  long MyVar1
  long Pointer_to_MyVar1

  long MyVar2
  long Pointer_to_MyVar2

OBJ
  MyObj1 : "MyObject"

PUB Main
  Pointer_to_MyVar1 := @MyVar1
  Pointer_to_MyVar2 := @MyVar2
  'then give the value of the pointer to the other object as a parameter 
  'of some kind of setup-method to the other object
  MyObj1.Start.....
  MyObj1.SetupPointers(Pointer_to_MyVar1,  Pointer_to_MyVar2)

now INSIDE the file MyObject.spin

there have to be variables for the pointervalues

VAR
  long Ptr1
  long Ptr2

PUB SetupPointers(p_Pointer1,  p_Pointer2)
  Ptr1 := p_Pointer1 'through this setup you can use the pointers in every PUB or PRI-method inside THIS object
  Ptr2 := p_Pointer2

'and then you can access the variables inside THIS object by

  long[noparse][[/noparse]Ptr1] := ....
  long[noparse][[/noparse]Ptr2] := ....

best regards

Stefan

Mike Green · 2008-11-04 19:45

heathclf,
What you've posted seems unnecessarily complicated, like why are you using pointers?

You've got the simple case of a method (subroutine) that is running in its own cog with everything together in one object. Good!

Here it is simpler:

VAR
Byte stack1[noparse][[/noparse]30], highTime

CON
   maxHigh = 1200*80
   minHigh = 975*80
   totalTime = 20000*80
   servoPin = 0

PUB main
   highTime := maxHigh
   cognew(PulseServo, @stack1)

   repeat until highTime < minHigh
      waitcnt(clkfreq + cnt)
      highTime := highTime - 100

PUB PulseServo | myTime

'This assumes that the pulseis going to an inverter (for 5VTTL conversion), and so the timing is reversed

   dira[noparse][[/noparse]servoPin]~~ ''Output Pins
   repeat
      myTime := highTime   ' reference it once so, if it's changed between the waitcnt's, the timing will still be correct
      waitcnt(totalTime - myTime + cnt)
      outa[noparse][[/noparse]servoPin]~
      waitcnt(myTime + cnt)
      outa[noparse][[/noparse]servoPin]~~

Post Edited (Mike Green) : 11/4/2008 7:50:32 PM GMT

Need a recommendation

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