Re: [PATCH v2] iio: adc: ltc2485: add support for Linear Technology LTC2485 ADC
From: Alison Schofield
Date: Fri Sep 02 2016 - 15:16:29 EST
On Mon, Aug 29, 2016 at 05:01:14PM +0100, Jonathan Cameron wrote:
> On 25/08/16 06:48, Alison Schofield wrote:
> > Adds basic support for the LTC2485 ADC - a delta-sigma analog-to-digital
> > converter with an I2C interface that operates in single shot conversion
> > mode.
> >
> > The driver supports an on board 5V reference and the power-on default
> > configuration which rejects both 50hz & 60hz line frequencies and
> > operates in 1x speed mode.
> >
> > Signed-off-by: Alison Schofield <amsfield22@xxxxxxxxx>
> > Cc: Daniel Baluta <daniel.baluta@xxxxxxxxx>
> > ---
> > Changes in v2:
> > - changed the wait conversion time function to use monotonic rather than
> > real time and to use milliseconds rather than nanoseconds.
> > - made conv time a constant int.
> >
> > Same notes as in v1:
> > Reviewers: In addition to commenting on what is present, please comment
> > on what is absent and the priority in which you would like to see
> > additional features added to this driver, or needed in this first submittal.
> None of the below are needed for initially submital.
> All 'value' add features at the end of the day. Job one: get reading from
> ADC done :)
>
> I made a few really small white space changes and applied this to the
> togreg branch of iio.git. Will be initially pushed out as testing
> in a few minutes time to check the autobuilders can't find anything.
>
> Thanks,
>
> Jonathan
>
> >
> > Not supported:
> > 1. External Vref
> > 2. Additional Configuration Modes
> > Temperature Sensor Mode: report temp data (not voltage).
> >
> > Line Frequency Rejection Mode: select to reject 50Hz or 60Hz
> > or both. (both is default)
> This is interesting... Will need some new ABI. It's a filter so we probably
> want to try and fit it in with the existing filter ABI.
> >
> > Speed Mode: Default speed mode (1x) performs two conversions each
> > cycle and combines the results. 2x speed mode only does one
> > conversion each cycle.
> Really simple case of oversampling. So this one is easy ;)
>
> > 3. Power management
> > 4. DT Bindings
> > 5. Triggered buffers
> Device is really slow, so no real rush on this one. Nice to have for
> the convenience of using standard interfaces in libiio etc, but
> at 7sps reading sysfs will work fine for all usecases!
>
> > 6. What else?
> Other power supply regulators..
> (allows complete power disabling if there is an appropriate controllable
> regulator on the board).
>
Thanks Jonathan!
I need more direction on the power supply regulators.
When you say power supply regulator, is that the same as reference
voltage?
The driver uses onboard vref now. I see how I can add support for an
external vref. But, it seems like maybe you are commenting that we can
have both, an external vref with an onboard vref as a fallback?
Thanks,
alisons