lkml.org 
[lkml]   [2024]   [May]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Supporting a Device with Switchable Current/Voltage Measurement
On Thu, May 02, 2024 at 01:36:23PM +0100, Jonathan Cameron wrote:
> Superficially sounds like you want a mixture of appropriate analog front ends
> and a Mux. I haven't tried the combination but it should be possible to do
> something like this with
>
> An IIO mux via this binding
> https://elixir.bootlin.com/linux/v6.9-rc6/source/Documentation/devicetree/bindings/iio/multiplexer/io-channel-mux.yaml
> (that includes a gpio-mux example).
>
> Consumed in turn by a pair of AFE devices.
>
> Then you should be able to just read from which ever of the AFE device you want.
> A sysfs read from
> /sys/bus/iio/devices/iio\:deviceA/in_voltage_raw
> will switch the mux to appropriate place then request the
> voltage from the iio-mux, which in turn requests it from the ADC IIO driver.
>
> /sys/bus/iio/devices/iio\:deviceB/in_current_raw
> switches the mux the other way and otherwise the flow as above.
>
> Jonathan
>

On Thu, May 02, 2024 at 03:49:03PM +0200, Peter Rosin wrote:
> I just realized that it's also possible to do this "the other way around". Maybe
> that makes more sense?
>
> Cheers,
> Peter
>
> mux: gpio-mux {
> compatible = "gpio-mux";
> #mux-control-cells = <0>;
>
> gpios-mux = <&main_gpio0 29 GPIO_ACTIVE_HIGH>;
> };
>
> rcs: raw-current-sense {
> compatible = "io-channel-mux";
> io-channels = <&adc 0>;
> io-channel-names = "parent";
> #io-channel-cells = <1>;
>
> mux-controls = <&mux>;
>
> channels = "raw-current", "";
> };
>
> rvs: raw-voltage-sense {
> compatible = "io-channel-mux";
> io-channels = <&adc 1>;
> io-channel-names = "parent";
> #io-channel-cells = <1>;
>
> mux-controls = <&mux>;
>
> channels = "", "raw-voltage";
> };
>
> current-sense {
> compatible = "current-sense-shunt";
> io-channels = <&rcs 0>;
> io-channel-name = "current";
>
> shunt-resistor-micro-ohms = <3300000>;
> };
>
> voltage-sense {
> compatible = "voltage-divider";
> io-channels = <&rvs 1>;
> io-channel-name = "voltage";
>
> output-ohms = <22>;
> full-ohms = <222>;
> };
>
> Cheers,
> Peter

A lot of good information. I didn't know about the iio-mux. It might
solve our problem, and I will do some testing with it.

Thanks a lot for the help!

Regards,
João Paulo Gonçalves

\
 
 \ /
  Last update: 2024-05-27 18:13    [W:0.052 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site