The project is battery powered water pile sensor.
Hardware: KIT0139 with SEN0262 Current to Voltage converter, cap 25V 330uF and boost buck converter 12v out 2.5-12v input.
Below I will refer to the KIT0139 pressure sensor as sensor.
The converter in is on the + vbat and - on gnd.
The converter out + high side to the SEN0262 and - to - of sensor.
Cap + on A0 and - gnd.
SEN0262 to 3v3, gnd and A0.
SEN0262 high side there is only the 12v source from the converter connected to test if A0 reads 0mV. The problem is it doesn’t.
With this configuration, it reads between around 150mV - 133mV. Without capacitor this range is way bigger. I would like to have it at 0 when sensor is not connected. This is the case when the input of the convertor is connected to its own power source. Not ideal to have 2 separate power sources. Something in the nrf9151 feather generates the 150-130mv offset. This offset is a bit to big to use the sensor reliably. With the ofset it would be like 7cm and without around 1-2cm. I could increase the cap capacity but this is non-optimal of the power that it uses.
Do you know this problem or have any suggestions?
So far I’m happy with the nrf9151 feather it’s a good product!
