Using Analog pin for battery voltage detection

Discussion about writing software for VS1005 and the VSOS Operating System. Also posts about VS1005-related hardware design and device drivers should be posted here.
treverwagenhals
Senior User
Posts: 21
Joined: Thu 2018-03-01 15:45

Re: Using Analog pin for battery voltage detection

Post by treverwagenhals » Fri 2018-06-08 14:47

So it appears that the IOVDD voltage value is actually 2.5V for some reason. So, it looks like this is running perfectly fine. That was my mistake, as I assumed it would be 3.3V read back.

While I'm mentioning it though, what is the easiest way to adjust the voltage value of IOVDD so that it will actually be 3.3V?

Hannu
Senior User
Posts: 36
Joined: Mon 2016-05-30 11:54

Re: Using Analog pin for battery voltage detection

Post by Hannu » Mon 2018-06-11 7:44

Hi!

IOVDD should be 3.3V or 1.8V unless it has been readjusted. 3.3V is selected by pulling GPIO0_7 up during boot.

Easiest is to use setclock program. First start without any parameters. It should show the IOVDD. Then change slightly (-iv) and see if it really changes. setclock -h gives brief help and VSOS shell document has rest of the information.

If voltage doesn't change, my first suspect would be something pulling IOVDD down on the board. LED without series resistor might do that.

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pasi
VLSI Staff
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Joined: Thu 2010-07-15 16:04

Re: Using Analog pin for battery voltage detection

Post by pasi » Tue 2018-06-12 11:28

Another possibility is that IOVDD is configured to 1.8V (GPIO0_7 being low during reset) and external connected devices using 3.3V drive current through the protection diodes which pulls the voltage up to 2.4-2.5V.

Either way, the problem should be located and fixed.
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