Input adc
Posted:
Tue May 24, 2016 11:51 pmby artic1980
Hello to all I have to convert the signal of a pH sensor that goes from -0.5 to +0.5 I must convert it to connect it to the analog input ADC that if I'm not mistaken reads from 0 to + 1 .
how can I do?
Thank
Re: Input adc
Posted:
Wed Jul 19, 2017 12:19 amby Javigrop
Could you solve it? I'm struggling with the same, I will use a voltage divider I think
Re: Input adc
Posted:
Thu Jul 20, 2017 11:07 pmby trackerj
You can find more informations about ESP8266 ADC in these related articles:
ESP8266 Internal ADCStep by step ADC input - voltage divider - the easy way exampleADC input - autorange frontend designA good example to follow is also this one:
Voltage Level Shifter and amplifier module for ACS712.
You will find there all the bits and pieces to design your own desired range high precision Voltage Level Shifter.
Happy breadboarding,
TJ
Re: Input adc
Posted:
Fri Jul 21, 2017 5:27 amby btidey
If you can tolerate losing some resolution in the interests of simplicity then you could just use a simple voltage divider plus an input resistor to offset negative bias of the sensor.
For example a 47K / 10K divider across the 3.3V to 0V and a 10K input from the sensor to the junction gives 0.09 -> 0.54V to feed into the ADC. This mean the swing from end to end is now only 0.45V rather than 1V.
This assumes the sensor has a low impedance compared to the 10K. Stability of the 3.3V rail is important.