4 ms·
> [ESP32 LOLIN32 Lite] Analog input maximum voltage 1.0V Where did this number come from? AFAIK all pins should operate at 3.3v, and I see no mention of a 1v
by declaredapple 3y ago
> [ESP32 LOLIN32 Lite] Analog input maximum voltage 1.0V
Where did this number come from?
AFAIK all pins should operate at 3.3v, and I see no mention of a 1v maximum for that board, or the esp-chip either.
- pantalaimon 3y agoUsually you have a reference voltage for the ADC, that is the maximum you can measure. A 1V band gap voltage reference is common. You could also use 3.3V Vcc instead, but there is no guarantee that that’s actually 3.3V as it's provided by an external circuit. The band gap voltage is always 1V, so I see why it would be the default.
- gh02t 3y agoThe ESP32 usually uses a 1.1V reference, however (unlike the ESP8266), it has a variable attenuation setting that allows you to measure voltages higher than Vref. https://docs.espressif.com/projects/esp-idf/en/v4.4/esp32/api-reference/peripherals/adc.html https://docs.espressif.com/projects/esp-idf/en/v4.4/esp32/ap... The Micropython code the post has at the bottom initializes the ADC to the default, which I think 0 DB attenuation setting, which gives you a range of roughly 0.1-0.95 V. It'll be fine physically if you hook it up to 3.3 V, but the readings will saturate unless you use the higher attenuation setting. There's not much advantage to enabling the attenuator for this test regardless, it just adds more noise.