PINE64
Spurious interrups from KEYADC - Printable Version

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Spurious interrups from KEYADC - StefanB - 01-30-2016

During U-Boot startup I see the following message repeated

Code:
key pressed value=0x1

This is obviously caused by interrupts from the KEYADC. As far as I can see, this pin is left floating, but should likely be weakly (1..10 MOhm) pulled to GND.

I assume the purpose of this pin is to implement an R2R ladder input, like

http://hackaday.com/2012/03/02/r2r-ladder-connects-multiple-buttons-to-one-adc-pin/

RE: Spurious interrups from KEYADC - tllim - 01-30-2016

(01-30-2016, 08:36 AM)StefanB Wrote: During U-Boot startup I see the following message repeated

Code:
key pressed value=0x1

This is obviously caused by interrupts from the KEYADC. As far as I can see, this pin is left floating, but should likely be weakly (1..10 MOhm) pulled to GND.

I assume the purpose of this pin is to implement an R2R ladder input, like

http://hackaday.com/2012/03/02/r2r-ladder-connects-multiple-buttons-to-one-adc-pin/

Good catch, I will inform our Android software engineer to check out.

RE: Spurious interrups from KEYADC - clode10164 - 11-29-2017

this is true on the ic ALLWINNER A64 MAIL IC it is the PIN A16 which is an analog input with 6bit resolution
in the documentation : http://files.pine64.org/doc/datasheet/pine64/A64_Datasheet_V1.1.pdf
look at page 8 and 9