ESP8266 Community Forum

- Tue Apr 10, 2018 2:18 pm #75265 Hello!

I have an ESP-07 from which I am trying to read voltage on A0 (not from internal ADC).
I thought 1V would equal 1024 but actually I need to put between 1.13 to 1.17V to get 1024 (not sure why it fluctuates "so" much).

Is that expected?

Thank you

- Tue Apr 10, 2018 3:33 pm #75266 The 1V value is a nominal value. It is not precision, it is not calibrated. The A/D measurement of the ESP8266 is one of it's weak points. Because of the poor A/D ability I use digital sensors when possible. Or an external A/D converter if I really need to measure a voltage.

- Wed Apr 11, 2018 2:26 am #75275

Or an external A/D converter if I really need to measure a voltage.

Do you have any recommendations?

I've ordered an ADS1115 a couple of days ago (4 ch, I2C); do you have any experience with it?

Assumption is the mother of all f*ckups. At least: that's what I'm assuming.

- Thu Apr 12, 2018 5:21 am #75313 It also depends a bit on what your intended usage of the ADC is.

Although the internal ADC initial scale is pretty variable from device to device ( I normally see +/- 5%), it is reasonably stable. I add a calibration factor into my ADC routines (adjustable remotely) and when this is used then the ADC is quite usable for things like battery monitoring.