Duration counter

Jkane · 2015-03-12 08:03

Hello,

i have another question

what I am doing is running a repeat for 1 second, during that one second i collect data, then break out using a repeat while, then I post a message and reset for the next second of reading

the issue that seems to be occuring is that most of the time, I get 1 second intervals, but every so off i get a burst of messages, as if the repeat while is being by passed.

I thinik it is the way I set up the one second interval. loop and the test are wrong

Here is the code

{Object_Title_and_Purpose}


CON
        _clkmode = xtal1 + pll16x                                               'Standard clock mode * crystal frequency = 80 MHz
        _xinfreq = 5_000_000

VAR
                
  long Transition_counter
  long pin_state
  long previous_pin_state
  long GPM
  long GPM_temp
  long Dt
  long record_number
  long t
 
  

OBJ
   term   : "FullDuplexSerial"
   fMath : "FloatMath"
  '  fMath : "Float32full"   
  fString : "FloatString"
  
PUB Main 

term.start(31, 30, 0, 115200)

record_number := 1

t := 0

dira[8]~  ' set to input := 0

dT  := clkfreq

repeat
  term.tx(13)
  term.str(string(" Rec Num: "))
  term.dec(record_number)
  record_number++
    
  t := clkfreq + cnt               ' get next second
  repeat while cnt < t              ' loop until second is up
     
     pin_state := ina[8]         ' check high or low
    
        if pin_state == previous_pin_state
             'do nothing
        else
            previous_pin_state := pin_state   ' make new pin state
            transition_counter++              ' and count the transision

I tried different ways, but the results is usually the same. most of the examples I have seen are using waitcnt for delays, but I want to process during the second, and not delay

regards

Jeff

kuroneko · 2015-03-12 08:09

Spin comparisons are always signed. IOW your repeat while cnt < t will occasionally misbehave. In this case I'd suggest using deltas (see FullDuplexSerial, rxtime method).

Mike Green · 2015-03-12 08:13

CNT is an unsigned 32-bit number while the less-than and greater-than operators work on 31-bit signed numbers, so "cnt < t" won't work as you expect. You need to do something like:

startTime := cnt
repeat while (cnt - startTime) < clkfreq
   'stuff

Jkane · 2015-03-12 09:05

Thank you,

works fine now, no runaway output

New code

 t := cnt
   repeat while (cnt - t) < clkfreq
       pin_state := ina[8]    ' check high or low

old code (which did not work)

't := clkfreq + cnt               ' get next second
  'repeat while cnt < t              ' loop until second is up

regards

Jeff

Duration counter

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