Why Is the Output Code Stuck at All Ones?
This could happen if the voltage reference is not working properly. Check the reference voltage. Perhaps the reference input was inadvertently shorted to ground. Use a handheld DVM to measure between the reference input and ground, right at the ADC’s pins. If the ADC has a shutdown pin, use an oscilloscope to verify that shutdown is not active. Some parts permit the shutdown pin to be left unconnected (floating); other parts require it to be driven high or low. Use an oscilloscope to check the DOUT pin of the ADC. See if the part is performing conversions. Perhaps there is a wire broken somewhere.
