KEAZ64AMLH ADC problem

[hansonhe]

Dear,

Problem Description:
We meet below problem for channel AD2 and AD3.
When AD2, AD3 two channel sampling. During the loading test, the AD2 connection wire will fall off, so AD2 pin PTA6 is not connected with other thing, at this situation we sample AD3, and then AD2, it is found that the value of AD2 changes with the change of AD3 value. In addition, if you read the value of the AD2 first and read the value of the AD3, this problem does not exist.
At present, all the boards can repeat the problem. The attachment is the test code and the schematic diagram. Please help see if there is any other special attention to ADC. Thank you.

[Robin_Shen]

Hi Hanson,

Same question in Case 00149224.
Consider the ADC is used to detect keyboard, it does not require very high accuracy.
Please pullup or pulldown a large resistor at ADC pin, it will ensure the ADC value to high or low when the ADC input is floating.

Best Regards,

Robin

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