Testing the 32kHz Watch Crystal

[espruino-discuss3]

Posted at 2015-02-04 by AntiCat

According to http://www.espruino.com/Clocks the Watch Crystal will automatically be detected and used.
I don't have an oscilloscope or a frequency counter.
Is there any way to verify that the Espruino did indeed switch to the crystal like a function that prints the status?

[espruino-discuss3]

Posted at 2015-02-04 by @gfwilliams

Sure - there's nothing built-in, but it's what I use for testing:

function getClockSource() {
  return ["NONE","LSE","LSI","HSE"][((peek32(0x40021020)&768)>>8)];
}
getClockSource();

It checks the actual registers in the chip to see what it's set to.

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Posted at 2015-02-04 by AntiCat

Thank you Gordon!

I listed the meaning of the abbreviations below, for any one else who might also use the snippet:
LSE = Low-speed external user clock
LSI = Low-speed internal
HSE = High-speed external user clock