Hi all,
On Apr 28, 2024, at 9:46 AM, Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
> Agreed - by my reading the original patch is correct. Maybe it would act
> as cleaner 'documentation' to have the sign_extend32() for the cold junction be
> from bit 12 rather than 15, but I'm not sure it's worth the effort.
>
> Andrew, would be great if you can review this fix in case we are all missing
> something!
I also agree that Dimitri’s original patch appears correct per the data sheet.
I think of the cold junction register as a 16 bit 2s complement signed integer,
despite the limited range. I like sign extending it from bit 15 rather than from 12.
I applied Dimitri’s patch and stuck a dev board in my icebox.
Before patch:
# cat /sys/bus/iio/devices/iio:device0/in_temp_raw
65222
# cat /sys/bus/iio/devices/iio:device0/in_temp_ambient_raw
65256
After patch:
# cat /sys/bus/iio/devices/iio:device0/in_temp_raw
-260
# cat /sys/bus/iio/devices/iio:device0/in_temp_ambient_raw
-212
Looks good to me! Thanks for the patch Dimitri, and thanks to all for the review!
Andrew
