Pico JS compilation issue with peek32/poke32

[espruino-discuss3]

Posted at 2016-04-06 by Trogdor1967

I tried to use the example code provided on the JS Compilation page: http://www.espruino.com/Compilation .

The code is as follows:

function toggler() {
  "compiled";
  var pB2 = 0|B2.getInfo().out_addr;
  var cnt = 1000000;
  for (var i=0;i<cnt;i++) {
    poke32(pB2, 1); // on
    poke32(pB2, 0); // off
  }
}

However, when I call toggler(), the pin does not change. If I substitute ...

digitalWrite(B1,1);

... for the first poke32(), it does work, generating a square wave with a large negative duty cycle. That makes sense, since much more code is executed before the digitalWrite() is complete.

Likewise, I can use digitalWrite to reset the pin, and poke32 to set the pin, and I get a square wave with a large positive duty cycle.

But, using poke32 for both set and reset generates no change on the pin.

Has anyone tried this example on the Pico? Can anyone confirm this problem?

[espruino-discuss3]

Posted at 2016-04-06 by @gfwilliams

Ahh, this is because the pin mode hasn't been set to an output first. digitalWrite does it for you (one of the reasons that it is slower)

Try:

digitalWrite(B2,0);
// or pinMode(B2, "output")
toggler();

I imagine that will work fine - I'll update the documentation to mention it.

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Posted at 2016-04-06 by Trogdor1967

That did it!

Thanks for the help, and I really am enjoying the Espruino!

Note: I get a 7MHz square wave, not 8MHz. Nice and fast, and proves the point about compilation and direct STM register access!

Screenshot attached.

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Attachments:

• 2016-04-06 11_24_30.jpg