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S12ZVC Supply Voltage Measurement

Question asked by Amit Dhand on Jul 9, 2015
Latest reply on Jul 9, 2015 by Radek Sestak



I am calculating Supply Voltage (12 volts ) through the ADC0 internal channel by enabling BATS module (which connects the VSUP with ADC channel).
MC9S12ZVCRM V1.2 Page 326 say that input Analog signal are unipolar and must be within the potential range of  VSSA to VDDA.


So accordingly


Supply Voltage - 12,000 mVolts

VSSA - 0,00 volts
VDDA - 5,000 mVolts


Using 12 bit resolution of the ADC, it should give result correctly but that is not the case it is not giving correct answers.

Am I measuring the Supply voltage correctly or need to step down the voltage or something else?


Thank you