Kinetis IO mux for Analog pin

[daweiyou]

Hi guys:

I have a question about analog pin, for example ADC0_SE pin, the default mux is ADC pin, and could change to GPIO output functionality after reset.

But before the GPIO output take effect, what's the output? Hi-Z or undifined?

[Jorge_Gonzalez]

Hello Dawei:

For digital-only pins, the default is Disabled (High Impedance). But for default analog pins, it depends on the internal circuitry. In this case for ADC, there is not an output, and the voltage level depends on your external circuitry. Give a check to the next diagram about internal circuitry for ADC pins:

Hope this helps.

Regards!,
Jorge Gonzalez

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[daweiyou]

Hi Jorge:

thx your reply.

the input pin, marked yellow, is other ADC input channel.

And from above simplified input circuit, the ADC pin, as ouput maybe undefined level, the Radin and Cadin determine Zadin, which is not large.