Pulse Measurement Help

lardom · 2018-06-11 02:16

I want to be able to measure 2.4ms, 1.2ms and 0.6ms. I looked at 'pos detector' and counter mode 24 26. They both look the same to me but I'm trying to figure out how to get it to return once the i/o pin goes low.
Will this work?

PUB test_counter_mode   

   frqa := 1
   ctra := 0
   dira[1]~       
  
   repeat      
     ctra := (%11010 << 26 ) | (1)                    ' accumulate while A = 1   
     waitpne(0 << 1, |< 1, 0)                                                   
     waitpeq(0 << 1, |< 1, 0)                                                                                                      
     pulseWidth := phsa  
     phsa:=0

Bean · 2018-06-11 12:13

I think you want something like:

PUB test_counter_mode   

   frqa := 1
   ctra := 0
   dira[1]~           
   ctra := (%11010 << 26 ) | (1)                    ' accumulate while A = 1   
   repeat
     waitpne(0 << 1, |< 1, 0)    ' wait for pin to go low
     phsa = 0                            ' Reset count
     waitpeq(0 << 1, |< 1, 0)    ' wait for pin to go high                                                                                                
     waitpne(0 << 1, |< 1, 0)    ' wait for pin to go low
     pulseWidth := phsa            ' Get the count

Bean

JonnyMac · 2018-06-11 12:41

You want to use POS DETECT mode like this:

pub main | pw                                                        
                                                                 
  setup

  ctra := (%01000 << 26) | PG_PIN                               ' POS DETECT mode
  frqa := 1

  repeat
    waitpne(PG_MASK, PG_MASK, 0)                                ' wait for low
    phsa := 0                                                   ' clear accumulator

    waitpeq(PG_MASK, PG_MASK, 0)                                ' wait for pulse                                                           
    waitpne(PG_MASK, PG_MASK, 0)
    
    pw := phsa / US_001                                         ' convert to microseconds

    term.dec(pw / 1000)                                         ' display as x.xxx
    term.tx(".")
    term.rjdec(pw // 1000, 3, "0")
    term.tx(13))

The attached program (tested on Propeller Activity Board) starts a pulse-generator in in a background cog so that the foreground code (above) can measure it. This is one of my favorite things about the Propeller: I can use a spare cog to simulate an input from a device that I don't have connected.

lardom · 2018-06-11 14:40

@Bean and @JonnyMac, Thanks very much. I see the similarity in some code that I got from the OBEX. It used 'counter mode 21' which looks like it returns a differential result. I have a difficult enough time wrapping my brain around 'single ended' results.
@JonnyMac, thanks for the zip. I'll be testing both IR and ASK. Testing wireless communication with only a single Propeller will make life 'so' much easier!

Bean · 2018-06-11 15:49

So is there any difference between "POS DETECT" mode and "LOGIC A" mode ?

Bean

JonnyMac · 2018-06-11 17:47

So is there any difference between "POS DETECT" mode and "LOGIC A" mode ?

I don't think so -- either works in the little demo I wrote.

@lardom Are you wanting to do this for SIRCS coms? If yes, I have an object that you're welcome to. I'm sitting in the Dallas office of a laser-tag client at the moment. The product using SIRCS type packets in the IR coms ("bullets" and command and information packets)

lardom · 2018-06-11 21:38

@JonnyMac
"@lardom Are you wanting to do this for SIRCS coms?"
Yes, kind of. I plan to tweak it a bit.
"If yes, I have an object that you're welcome to. I'm sitting in the Dallas office of a laser-tag client at the moment. The product using SIRCS type packets in the IR coms ("bullets" and command and info`rmation packets)"
Yes, I would appreciate it. I had success with the nRF24L01 transceivers even though my modules turned out to be clones. I would have posted the code but I didn't get the sense that there's much interest in the project that I built with it.
Now I want to see what I can do with 433Mhz modules.

DigitalBob · 2018-06-11 22:03

I think I found this one on the forum

JonnyMac · 2018-06-11 22:34

Yes, kind of. I plan to tweak it a bit.

Here's my generic SIRCS receiver -- do with it what you will!

lardom · 2018-06-12 00:37

@JonnyMac, thank you.
I don't know why wireless transmitters that use data as opposed to multiple channels aren't more popular but I think there are definite advantages. I can imagine some pretty amazing things if the code is written in PASM!

Pulse Measurement Help

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