I've got a mysterious problem with my ADC12 on my MSP430F235. Independently of using it in single or sequence conversion mode, the ADC seems to be not able to use his full-scale range from 0V to 2.5V (internal reference voltage). It behaves like this:
Input voltage: 0V => ADC value: 0 => RIGHT
Input voltage: about 1.95 V => ADC value: about 3180 => RIGHT
Input voltage: about 2 V and more (but less than 2.5 V) => ADC value always 2047 (constant) => WHY THAT?
Curiously the channels A1 and A2 are both only able to measure voltages above 1.25 V e.g. ADC values larger than 2047. Voltages below 1.25 V always result in ADC values 0.
I also measured the 2.5 V reference voltage, which is pretty okay. Of course I also checked my hardware for short circuits, but everything is fine and the voltages to measure appear correctly at the analog input pins of the microcontroller.
Has anyone ever had this problem or an idea what can be wrong?