assignment problem - am I stroked with blindness?

virtuPIC

I want to measure period times of an input pin signal. To test the code I want to run debug output on the same cog. To reduce the data load to a reasonable amount I try to run the output only ten times per second. The code fails: Debug output is sent every loop cycle. Find the stripped down code below. It should print the values of cnt and variables cntdisplay and cnt0 ten times per second. I see many more writings - but cntdisplay always has value 0. That am I missing here?

Any help appreciated!

CON
  _clkmode = xtal1+pll16x
  _clkfreq = 80_000_000

OBJ
  pc :  "PC_Text"
   
PUB theremin | cnt0, cntdisplay
  pc.start(pc#TXPIN)
  cntdisplay := cnt
  repeat
    cnt0 := cnt  
    'delay will go here
    cnt0 := cnt - cnt0
    if cnt - cntdisplay >= clkfreq / 10
      pc.dec(cnt)
      pc.str(string(" "))
      pc.dec(cntdisplay)
      pc.str(string(" "))
      cntdisplay := cnt
      pc.dec(cnt0)
      pc.str(string($0d))

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Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys

Post Edited (virtuPIC) : 5/15/2009 11:58:15 AM GMT

James Long

virtuPIC said...
I want to measure period times of an input pin signal. To test the code I want to run debug output on the same cog. To reduce the data load to a reasonable amount I try to run the output only ten times per second. The code fails: Debug output is sent every loop cycle. Find the stripped down code below. It should print the values of cnt and variables cntdisplay and cnt0 ten times per second. I see many more writings - but cntdisplay always has value 0. That am I missing here?

Any help appreciated!

CON
  _clkmode = xtal1+pll16x
  _clkfreq = 80_000_000

OBJ
  pc :  "PC_Text"
   
PUB theremin | cnt0, cntdisplay
  pc.start(pc#TXPIN)
  cntdisplay := cnt
  repeat
    cnt0 := cnt  
    'delay will go here
    cnt0 := cnt - cnt0
    if cnt - cntdisplay >= clkfreq / 10
      pc.dec(cnt)
      pc.str(string(" "))
      pc.dec(cntdisplay)
      pc.str(string(" "))
      cntdisplay := cnt
      pc.dec(cnt0)
      pc.str(string($0d))

I would probably rearrange some of this to be easier to read like this:

CON
  _clkmode = xtal1+pll16x
  [s]_clkfreq = 80_000_000[/s]
  _xinfreq = 5_000_000
 
OBJ
  pc :  "PC_Text"
   
PUB theremin | cnt0, cntdisplay, Time_delay

  Time_delay = clkfreq/10
  pc.start(pc#TXPIN)
  cntdisplay := cnt
  cnt0 := cnt
  cnt0 += Time_delay  
  repeat  
    'delay will go here
    'cnt0 := cnt - cnt0 <----- I would comment out this line but I'm not sure what you are trying to see.
    if cnt >= cnt0
      pc.dec(cnt)
      pc.str(string(" "))
      pc.dec(cntdisplay)
      pc.str(string(" "))
      cntdisplay := cnt
      pc.dec(cnt0)
      pc.str(string($0d))
      cnt0 += Time_delay

James L

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James L
Partner/Designer

Lil Brother SMT Assembly Services

Post Edited (James Long) : 5/15/2009 10:03:30 AM GMT

Chris Micro

_clkfreq = 80_000_000
if cnt - cntdisplay >= clkfreq / 10

underline?

In my programms the headline looks like this:
CON

_clkmode = xtal1 + pll16x ' sysclk setup

_xinfreq = 5_000_000

OneSecond = 80_000_000 ' number of sysclk cycles during one second

James Long

Chris Micro said...
_clkfreq = 80_000_000
if cnt - cntdisplay >= clkfreq / 10

underline?

In my programms the headline looks like this:
CON

_clkmode = xtal1 + pll16x ' sysclk setup

_xinfreq = 5_000_000

OneSecond = 80_000_000 ' number of sysclk cycles during one second

Ha, didn't catch that.

James L

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James L
Partner/Designer

Lil Brother SMT Assembly Services

virtuPIC

Chris Micro said...
_clkfreq = 80_000_000
if cnt - cntdisplay >= clkfreq / 10

underline?

In my programms the headline looks like this:
CON

_clkmode = xtal1 + pll16x ' sysclk setup

_xinfreq = 5_000_000

OneSecond = 80_000_000 ' number of sysclk cycles during one second

What do you mean with 'underline'? Writing '_clkfreq' and reading 'clkfreq' is perfectly correct according to the propeller manual. The other way round is wrong.

I just looked up '_clkfreq' vs. '_xinfreq' in the manual. Both are possible. You can read the number of sysclk cycles per second from 'clkfreq' - no matter which of the two you define.

I tried your proposal. Doesn't help. Anyway, I hadn't expect it would since the problem doesn't seem to be in the counter.

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Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys

mpark

    if cnt - cntdisplay >= clkfreq / 10

">=" does not mean "less than or equal"; it is an assignment operator. "a >= b" is the same as "a := a > b". Use "=>" instead.

virtuPIC

mpark said...
">=" does not mean "less than or equal"; it is an assignment operator. "a >= b" is the same as "a := a > b". Use "=>" instead.

AAAaaarrrggghhh!!!!!! I was stroked with blindness. I know why I prefer to program in PASM instead of SPIN.

This little correction helped a lot.

Thank you very much!!!

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Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys

mpark

Of course I meant to write "greater than or equal".

Rayman

This is another thing pushing me towards the C compiler... It's hard programming in C++ and SPIN at the same time!

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My Prop Info&Apps: ·http://www.rayslogic.com/propeller/propeller.htm

agodwin

I keep writing ':=' in my C code .. :-(

virtuPIC

Yeah... Regarding operators SPIN has some great features. Some additional operators that directly map to propeller instructions (e.g. ||, **, ~>, <----). Some more or less usable features that abbreviate the code a little (e.g. ~, ~~, |<...). But some operators that are different from the equivalent operators in C, Java et al. (e.g. :=, @, >=, ?...)

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Airspace V - international hangar flying!
www.airspace-v.com/ggadgets for tools & toys