How long to wait after configuring adc?

[rickstuart]

Hi,

I'm multiplexing a processor pin between a digital-out (SPI/Clock) and an analog-in.  Every time I switch to the analog-in I make about a dozen test reading separated by 100ms.  Every time the reading start high and drop.  Not stabilizing for 3 or 4 reading.  That's 300ms to 400ms of waiting!  I scoped the processor pin and looked at many events.  The voltage during the analog-in phase is rock-steady-flat. That leaves the processor.

So, what's going on inside the processor?  Why does the processor's ADC feature take hundreds of milliseconds to stabilize?

-thanks

[kerryzhou]

Hi rich stuart,

    Thank you for your updated information, and that's very good to hear your problem is solved.

    If you still have question about this topic, you still can let me know!

Have a great day,
Jingjing

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[rickstuart]

The ADC was not initialized correctly.  Works good now.