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kaluma-project / kaluma

A tiny JavaScript runtime for RP2040 (Raspberry Pi Pico)
https://kalumajs.org
Apache License 2.0
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Cannot access VSYS(GPIO29, ADC3) on rp2 #504

Closed Runc2333 closed 2 years ago

Runc2333 commented 2 years ago

According to Raspberry Pi Pico's official documentation...

A few RP2040 GPIO pins are used for internal board functions, these are:
GPIO29 IP Used in ADC mode (ADC3) to measure VSYS/3

But I can't use analogRead(29) or board.adc(29).read() to get the voltage at VSYS. This is important when a battery is connected at VSYS and estimate its charge by voltage. Could you help me with that?

Runc2333 commented 2 years ago

Also, I mentioned that if I flash the rp2 a few times (maybe 5~6 times) without the power cut, the board will hang up until you reconnect it's power. Is this a bug or is it just designed this way?

niklauslee commented 2 years ago

@communix Can you comment on this?

Runc2333 commented 2 years ago

@niklauslee I build a version of kaluma which changes targets/rp2/src/adc.c from

if ((pin >= 26) && (pin <= 28)) {
  return pin - 26;  // GPIO 26 is channel 0
}

to

if ((pin >= 26) && (pin <= 29)) {
  return pin - 26;  // GPIO 26 is channel 0
}

and it just works. board.adc(29).read() * 10 - 0.1 equals the voltage at VSYS.

Runc2333 commented 2 years ago

I created a pull request for this, you can review it to check if it works.