- Thu Feb 07, 2019 12:43 pm
using the 400k in series to the "reserved" pin is applying a voltage divider by using this and the internal 100k between esp_A0 and gnd, leaving alone the 220k between esp_A0 and analog in of nodemcu.
You could also just use an 180k in series going to analog in of nodemcu (resulting in 220k+180k // 100k == same 400k // 100k divider @ esp_A0). As the acs712 has a buffered output, there should be no problem with the 80k load.
This would (in plain theory) spread the 1V range of the esp to 5V. How linear and how exakt the 5V would equal the 1023 value is another story ...