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About the MC56F82748 of ANB1 ADC pin impedance

Question asked by Kris Ke on Mar 30, 2016
Latest reply on Apr 6, 2016 by Kris Ke


I measure the MC56F82748 demo board.


Measuring the impedance other impedance of ADC pins are normal about Mohm.


but measuring the GPIOB1 / ANB1 impedance just only about 3kohm.


I wanted to clarify whether the question on the register settings, the trouble you help.


1. want you to use your company's example code to measure ANB1 impedance.


2. If the measured impedance and 3kohm ANB1 many difference, please provide example code.


I have try the ADC function. I try use same resistor divider, but get difference result.


I use two 4.6kohm divider, but the measure is very difference.


If I use ANB1 get the ADC result is 10032 and use ANB0 get result is 16208.


According to calculations, the 16208 is right, why the ANB1 result is wrong.