ESP8266 Community Forum

- Sun Oct 04, 2015 11:51 am #30482 Hi there,
i found a strange behavior of the internal ADC of my NodeMCU v.0.9 (the yellow one):
after setting:

ADC_MODE(ADC_VCC);

I tried to read VCC:

Serial.printf("Vcc: %d \n",analogRead(A0));

but get always 65535 !

Has anybody got same results ?
Any idea on how to solve/work around this problem ?

Regards

Paolo

- Sun Oct 04, 2015 1:29 pm #30495

Serial.printf("Vcc: %d \n",analogRead(A0));

Try ESP.getVcc() (no parameter) instead of analogRead().

More details here

https://github.com/esp8266/Arduino/blob ... cific-apis

- Sun Oct 04, 2015 2:03 pm #30498 Here's a working snip from my Nodemcu LUA , maybe this will help ?

adc_id = 0
adc_val = 512


adc_value = adc.read(adc_id)
if adc_value > 1023 then
adc_value = 1023
elseif adc_value < 0 then
adc_value = 0
end

- Thu May 19, 2016 11:46 am #47667 I would like to do the following:

First read Internal VCC (get_vcc) and then continue reading an Analog Input with ReadAnalog. This would require me to have a pin connected to A0.

How can i achieve this?