Re: [PATCH 2/2] iio: temperature: ltc2983: Add support for ADT7604

["Nuno Sá" <noname.nuno@gmail.com>]

On Fri, May 08, 2026 at 12:46:50PM +0000, Stan, Liviu wrote:
> On Fri, 8 May 2026 Jonathan Cameron wrote:
> > > > As for the IIO_TEMP question, the chip's custom sensor table stores
> > > > temperature in Kelvin (same as the LTC2984 custom RTD table). For the
> > > > leak detector, coverage data is encoded as (P + 273.15) K, so when the
> > > > chip converts Kelvin to Celsius on output, after the driver applies the
> > > > 1000/1024 scale, the IIO output is P * 1000 millidegrees C - 0% reads
> > > > as ~0 millidegrees, 100% reads as ~100000 millidegrees. But yes, the
> > > > actual useable quantity is coverage percentage, not temperature. Is there
> > > > a more suitable existing IIO channel type for coverage percentage?
> > > >
> > >
> > > Will defer this to Jonathan but if we can have a real of the coverage
> > > given the temperature, I guess this is ok. Given that I think we don't have
> > > a better channel (unless we add one?) for this. Or just extended_info...
> > >
> > 
> > I have no idea what coverage percentage means in this case.
> > Can you provide some more details or a reference?  Google isn't giving me
> > anything useful.
> 
> A leak detector is a sensor like the raindrop detection modules, whose 
> resistance decreases as more of its surface is contacted by liquid. In this case, 
> for example, if half of the sensor's surface is in contact with a liquid, the 
> ADT7604 should, with an appropiate user-provided resistance-vs-coverage 
> table, report 50% coverage in the IIO channel.

And, AFAIU, depending on the coverage the resistance changes and that's
how we get into the indirect temperature variations?

- Nuno Sá

> 
> Thanks,
> Liviu