I've looked through the archives and as such I am using a 220ohm resistor to read the voltage of 4mA-20mA humidity sensor that takes 12-24vdc. I've mapped the sensor readings as follows: senConv = map(senReading, 180, 900, 0, 100)
where 4mA*220ohms= .88v 20mA*220=4.4v and for mapping 180= .88v/5v*1023 900=4.4v/5v*1023
The problem that I am having is that the sensor will not read above 70% humidity which is equal to around 3 volts. Is it possible that the resistor is causing too much of a voltage drop such that the 0-5v scale can not be realized?
Thanks in advance for any feedback.