require("IRReceiver") - out of memory (eventually)

[espruino-discuss]

Posted at 2016-05-26 by Wilberforce

require("IRReceiver").connect(NodeMCU.D1, function(code) {
  console.log(code);
  if ( code.length >= 33 ) {
    var l=parseInt(code.slice(1,16),2);
    if ( l === 15344 ) {
        lcd.setCursor(0,1);
      var k=parseInt(code.slice(17,21),2);
      console.log({k:k,b:button[k]});
      lcd.clear();
      lcd.print(button[k]);
    }
  }
});

I have discovered at night a fluro lamp triggers the IR reciever. These random pulses after a couple of hours trigger this:

11111111111111111111111111111111111111111111111111111111111101111111111110111
11111111111111111110111111111111111111111110
1111111111111111111111111111111111111111111110111111111111111111101111
11111111111111111111111111111111011111111111
0111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111101111111111111111111111111111111111111110111111111111110111101111111111111111111111111111111111111111111111110111111111111111111111111111111111111111111111111111111
11111111111111111111110111011111111111111111111111111111111111111111110111111111111111111111111111110111111111111111111111111101111111111111111111110111111111111111111111111011111111111111111111111011111111111111111110111111111111111111111111111111111111111111111101010111111111111111111111111111111111111111111111110111011111111111111111111111111111111111101111111111111111111101101111111011111111111111111011111111111111111101111111111111111111111111111111111111111011111111111101011111111111111111111111
ERROR: Out of Memory!
ERROR: Ctrl-C while processing watch - removing it.
Execution Interrupted during event processing.
at line 1 col 40
...astTime;b&&(clearTimeout(b),b=void 0);.04<c?(""!==a&&e(a),a=...
                              ^
in function called from system
> 

it appears to be in this block:

 // set our callback to happen whenever pin goes low (eg, whenever pulse starts)
  setWatch(function(e) {
    var d = e.time-e.lastTime;
    if (timeout) {
      clearTimeout(timeout);
      timeout = undefined;
    }

I believe the cause is here:

    if (d>0.04) { // a gap between transmissions
      if (code!=="") callback(code);
      code = "";
    } else {
      code += 0|d>0.0008;

So code just keeps getting longer.... I wondering what the best way is to make this robust?

Set a watch dog timer that truncates the code string if it gets too long, or simply controls it's length?

http://www.espruino.com/modules/IRReceiver.js

[gfwilliams]

Posted at 2016-05-26 by @gfwilliams

I wonder how long the string actually was?

Some kind of timer might be a good idea as you say - but then it screws up the low power sleep states on the proper Espruino boards as it'll be waking up every so often.

I guess the other option is to replace if (d>0.04) { with if (d>0.04 || code.length>100) {

Hopefully it won't add too much to the execution speed.

[espruino-discuss]

Posted at 2016-05-26 by Wilberforce

Not sure how to determine the string length. - I could save to this in a local version of the module and monitor that.

I'll try the 100 length.

The remotes I have seem to send 1's after fixed length (33 bytes in most cases) as repeat code if a button is constantly hit. If the constructor knew the length, a repeated event could be emitted. Not sure how to handle or perhaps retrigger the code sent?
I've bee also thinking about how the codes could be shortened instead of sending a string of 1 and 0's, perhaps a hex code?

[gfwilliams]

Posted at 2016-05-26 by @gfwilliams

The remotes I have seem to send 1's after fixed length (33 bytes in most cases) as repeat code if a button is constantly hit

Yes, but they do this after a gap - which if (d>0.04) should normally pick up? Perhaps it's one of those ESP8266 gotchas again - after all, this module's been around for years and nobody has reported a problem with it before.

Potentially you could have a varying length, but it does complicate usage - and you might want to use the same receiver to detect different types of remote controls which have different signal lengths.

I've bee also thinking about how the codes could be shortened instead of sending a string of 1 and 0's, perhaps a hex code?

It's done this way for speed of processing - single character string appends are nice and fast, so I wouldn't advise changing it.

Realistically bits come in once a millisecond maximum, so to fill up available memory 0 even on an ESP8266 - you've got to have a continuous burst of 10 seconds of IR. I think that's so unlikely that memory efficiency isn't really an issue.

What's the 'fluro lamp' that's triggering the receiver, and are you using a proper receiver?

Maybe you could check getPinMode on the receiver pin, to make sure it really is in input_pullup mode.

Most receivers need a ~40kHz series of IR pulses to trigger, and then to run out of memory there needs to not be a gap of more than 40ms for a whole 10 seconds. It all seems really unlikely unless something is wrong.

[espruino-discuss]

Posted at 2016-05-27 by Wilberforce

if (d>0.04 || code.length>100) {

Seems to have fixed the issue.

Would you like me to do a pull request?

[gfwilliams]

Posted at 2016-05-27 by @gfwilliams

Yes, that'd be great - thanks!