Generateing multiple Frequencies

Armondo522

Hi,
I am new to the Propeller Chip. It looks like I can find lots of uses for it. But i am having a tough time getting over this one hurdle. I am trying to generate 4 distict frequencies on 4 different output pins. I have loaded up the demo Freq sysn program, and it will let me generate only 2 of the 4 freq's i need. I have enclosed a sample of the code... Any suggestion will be appreciated..


Thanks...


CON
· _CLKMODE = XTAL1 + PLL16X
· _XINFREQ = 5_000_000
· Pin·· = 0
· PinA· = 1
· PinB· = 2
· PinC· = 3
· Frequency = 204_700·································· 'DC to 128MHz
· FrequencyA = 245_760
· FrequencyB = 1_600_000
· FrequencyC = 1_900_000
·
VAR
long stack[noparse][[/noparse]20]
OBJ
· Freq : "Synth"
·
PUB CTR_Demo
·
· cognew(Freq.Synth("A",PinB, FrequencyB),@stack)
·· Cognew(Freq.Synth("B",PinC, FrequencyC),@stack)
···· Freq.Synth("A",Pin, Frequency)
·· Freq.Synth("B",PinA, FrequencyA)

Mike Green

You only need one additional cog to generate 2 signals. You can't use the same stack space for two cogs running at the same time. Try this:

PUB CTR_Demo
  cognew(SecondCtr,@stack)
  Freq.Synth("A",Pin,Frequency)
  Freq.Synth("B",PinA,FrequencyA)
PUB SecondCtr
  Freq.Synth("A",PinB,FrequencyB)
  Freq.Synth("B",PinC,FrequencyC)

Armondo522

Thanks Mike for the fast response

This is what i have put in the program,




CON
· _CLKMODE = XTAL1 + PLL16X
· _XINFREQ = 5_000_000
· Pin·· = 0
· PinA· = 1
· PinB· = 2
· PinC· = 3
· Frequency = 204_700·································· 'DC to 128MHz
· FrequencyA = 245_760
· FrequencyB = 1_600_000
· FrequencyC = 1_900_000
·
VAR
long stack[noparse][[/noparse]18]


OBJ
· Freq : "Synth"
·
··
PUB CTR_Demo
· cognew(SecondCtr,@stack)
· Freq.Synth("A",Pin,Frequency)························ 'Synth({Counter"A" or
··Freq.Synth("B",PinA,FrequencyA)
·repeat················································ 'loop forever to keep cog alive

PUB SecondCtr
· Freq.Synth("A",PinB,FrequencyB)
· Freq.Synth("B",PinC,FrequencyC)

··But,·Frequency B & C still do not work, Also I do not understand why the synth module is so particular when passing the A & B parameters. I originally Added C & D IF statements just to try and the whole module stopped working.··I see how it should work, but it doesnt...

thanks again..


···

Mike Green

I think you will need a repeat in SecondCtr as well. I'm sorry I didn't think of it. Without the repeat or something similar, the method returns at its end and this causes an implicit stop which shuts down the counters in the cog.

If you look at the code for Synth, it just does some calculations, then sets up either the A counter or the B counter based on the first parameter. There's an A and a B counter and other associated registers for each cog, so you can set up two independent frequency outputs per cog. The A and B counters are identical in function and each consist of two identical sets of 3 registers (CTRx,PHSx,FRQx) and associated logic.
Mike