[meta-xilinx] JTAG versus OS - XADC differences in temperature

[Giordon Stark]

I should note that the reason I ask is that when I program the board
without loading the OS - i find that the Hardware Manager's output over
JTAG is working as expected. When I program the board, and boot from the
SDCard - I find that the JTAG output is not working correctly.

On Fri, Mar 24, 2017 at 1:40 PM Giordon Stark <kratsg at gmail.com> wrote:

> Hi,
>
> I'm not sure if anyone's seen this before or if I'm doing something wrong.
> http://i.imgur.com/KPRvx42.png - here's a screenshot of what I'm seeing
> through the Hardware Manager for a Zynq-7000 (7020 evaluation) board. In
> the OS, I combine the numbers from three memory-mapped files to calculate
> the temperature of the board.
>
> On average, i'm seeing ~42C from the OS via command line, while I'm seeing
> ~47C over JTAG in the hardware manager. Is there a known discrepancy? Which
> do I trust more?
>
> Command I run:
>
> $ cat /sys/devices/soc0/amba at 0/f8007100.ps7-xadc/iio\:device0/in_temp0_*
> | tr '\n' '\t' | awk '{print ($1 + $2)*$3}'
>
> Note that
>
> $ cat /sys/devices/soc0/amba at 0/f8007100.ps7-xadc/iio\:device0/in_temp0_*
>
> produces an output like
>
> -2219
> 2584
> 123.040771484
>
> So it just looks like I'm meant to add the first two, and multiply by the
> 3rd -- and this gives me a number in milliCelsius.
>
> Giordon
>
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