Spin demo code for the TSL235?

vanmunch

Hey everyone, I'm evaluation some different color sensors and I would like to try a TSL235 (?R?), but I haven't been able to find any Spin code for it. http://www.parallax.com/product/604-00084 There is an example for using an Arduino from Parallax, but nothing for the Propeller chip. I think the world is upside down....
http://learn.parallax.com/tsl235r-light-frequency-converter-arduino-demo

I've also checked the Obex and no luck, does anyone have a simple demo that they would be willing to share?

Thanks for your time,

Dave

vanmunch

Phi suggested a work around that I tested and found that it works here. http://forums.parallax.com/showthread.php/159974-My-suggestion-is-that-if-you-sell-a-sensor-provide-Spin-demo-code.

JonnyMac

There are many more ways to "skin the cat" as it were when using the Propeller. Do you want to read the frequency periodically, or would you like to devote a cog so that you have constant updates? If the latter, how often? Is once per second enough?

vanmunch

JonnyMac wrote: »

There are many more ways to "skin the cat" as it were when using the Propeller. Do you want to read the frequency periodically, or would you like to devote a cog so that you have constant updates? If the latter, how often? Is once per second enough?

Hey JonnyMac,

Thanks for asking.

The goal is to find the best method and sensor(s) for detecting (individually) red, green, blue, IR, & UV light reflected from an object about 2-3 inches away.
I've currently been testing a number of different sensors (photo-resistors, photo-resistor diodes, TSL235, etc.) In the end I'll create an array of 5-12 covering an area about 8 inches wide. The refresh rate will need to be at least 10 hz. I had been planning on dedicating a cog for this job.

BTW I always enjoy reading your articles in N&V.

Dave

JonnyMac

I don't have one of those sensors, but I do know how to program the Propeller. I did a direct port of the Arduino demo in just a few minutes. I set the loop time to 10ms so that the output would be an even fraction (1/100) of the input frequency. Since I don't have one of those sensors I used the Synth object to create a test frequency.

var

  long oldcount 
  long temp 
  long avg 
  long freq 
  long loopcount 


pub main | t

  setup

  t := cnt
  repeat
    waitcnt(t += (10 * MS_001))
    temp := phsa                                                 ' capture current count
    freq := temp - oldcount
    avg := avg + freq
    if (++loopcount == 25)
      term.tx(CR)
      term.dec(avg / 25)
      term.tx(CLREOL)
      avg := 0
      loopcount := 0
    oldcount := temp


pub setup

'' Setup IO and objects for application

  term.start(RX1, TX1, %0000, 115_200)                           ' start serial for terminal

  ctra := (%01010 << 26) | TSL                                   ' setup pin to count positive edges
  frqa := 1

  ' for testing only -- remove this line when sensor is connected

  synth.synth("B", TSL, 300_000)

The key to my code is using a counter in POSEDGE mode -- this mimics the edge-triggered interrupt of the Arduino. You can easily drop this code into a Spin cog to provide a count/period to your foreground application.

JonnyMac

Here's how easy it is to monitor the sensor in the background, getting an update every 100ms (10Hz) -- as you would expect, the result is the input frequency frpm the TSL235 / 10.

var

  long  cycles


pub main | t

  setup

  t := cnt
  repeat
    waitcnt(t += (10 * MS_001))
    term.tx(HOME)
    term.dec(cycles)
    term.tx(CLREOL)


pub setup

'' Setup IO and objects for application

  term.start(RX1, TX1, %0000, 115_200)                           ' start serial for terminal

  cognew(run_tsl235(TSL, @cycles, 100), @tslstack)               ' start TLS monitor cog
  

  ' for testing only -- remove this line when sensor is connected

  synth.synth("B", TSL, 300_000)



con

  { ----------------------------- }
  {  T S L 2 3 5   M O N I T O R  }
  { ----------------------------- }


var

  long  tslstack[32]
  

pri run_tsl235(pin, p_result, ms) | new, old, t

'' Monitor TSL235
'' -- updates long at p_result every ms milliseconds

  ms *= clkfreq / 1000                                           ' convert ms to ticks

  new := 0
  old := 0
  
  ctra := (%01010 << 26) | pin                                   ' setup pin to count positive edges
  frqa := 1
  phsa := 0

  t := cnt                                                       ' sync with system timer
  repeat                                                         ' loop forever
    waitcnt(t += ms)                                             ' wait ms milliseconds
    new := phsa                                                  ' capture current count
    long[p_result] := new - old                                  ' report count to foreground
    old := new                                                   ' save for next cycle

Tracy Allen

Are you also considering integrated RGB color sensors, such as the TCS3472, TCS3490 or ISL29125? Those use the i2c interface.