MorganS:
PA5/AN4/VREF can be configured to do at least 3 different things. That's why it has 3 names. From the outside, it is impossible to tell what it is configured as.Most likely it is an analog input, but they could be doing something clever by operating it in its VREF mode.
how can i just use the bare sensor and get the math to make this thing read. i have a calibration solution to help me get the numbers right but i dont know how to get the numbers or calculate the resistor.
i have a cheap water conductivity pen that has a broken lcd screen and i was able to disassemble the meter and recovery the sensor in working order. the sensor is no more that 2 metal probes that measure conductivity via a reference voltage. my question is how can i calculate the resistor and math in the code to make this work. i could feed this sensor 3.0v and read the voltage on the other end but i dont know how to make sense of the number. i can however make a know calibration solution to help me calibrate the numbers?