Re: [PATCH] iio: light: as73211: Increase measurement timeout

[Christian Eggers]

On Wednesday, 9 September 2020, 18:58:39 CEST, Andy Shevchenko wrote:
> On Wed, Sep 9, 2020 at 6:45 PM Christian Eggers <ceggers@xxxxxxx> wrote:
> > We found some sensors which are much slower (20% at room temperature)
> > than nominal. According to the data sheet, up to 27% is possible. Now I
> > add 33% to the nominal time out, hopefully this is enough.
> 
> I'm wondering if this is a function of temperature.
> And if that has an actual thermistor inside...
 I haven't designed the hardware, but I guess that clock generation is done 
using an RC oscillator which depends on temperature. Temperature measurement 
is possible, but I think the recommended way is to externally control the 
integration time using the SYN pin and to get the actual number of RC cycles 
from a register. But generating the required waveform for the SYN pin using a 
uC general purpose timer seems challenging.

I wouldn't be surprised if the measurement results also depend on the exact 
value of the supply voltage.