Board Sensor Calibration

[Patrick Williams]

On Thu, Aug 20, 2020 at 11:15:33AM -0500, Patrick Williams wrote:
> On Wed, Aug 19, 2020 at 10:39:15AM -0700, Maxim Sloyko wrote:
> > Hi OpenBMC!
> > 
> > We would like to have a value reported by a certain sensor changed
> > according to our calibration results. This is a temperature sensor and the
> > calibration has nothing to do with the sensor itself -- so no need to
> > change the driver or anything -- but with a sensor placement on the board.
> > Basically we want to infer the temperature at a different location by
> > calibrating the sensor.
> > 
> > Are there any tools in OpenBMC that would allow us to add the calibration
> > curve to, say, phosphor-hwmon and have it report the value different from
> > the one reported by the underlying sensor? Did anybody else have to deal
> > with something like this and what was your solution? Do people more
> > familiar with sensor architecture have any recommendations on how best to
> > handle this?
> > 
> > Thank you.
> > 
> > -- 
> > -MS
> 
> There is work being implemented now under phosphor-virtual-sensor[1]
> which is intended to cover exactly this case (among others).  We have a
> similar situation where sensors need to be calibrated based on values
> from one or more other sensors.  An example might be a voltage regulator
> which reads high as it gets hotter.  phosphor-virtual-sensor will allow
> you to forumlate a secondary sensor (the "virtual" sensor) using math
> applied to one or more real sensors.
> 
> -- 
> Patrick Williams

Forgot to include the link.

1. https://gerrit.openbmc-project.xyz/q/status:open+project:openbmc/phosphor-virtual-sensor

-- 
Patrick Williams
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