On 01/06/2024 21:35, Jonathan Cameron wrote: > On Fri, 31 May 2024 22:42:27 +0300 > Dumitru Ceclan via B4 Relay <devnull+dumitru.ceclan.analog.com@xxxxxxxxxx> wrote: > >> From: Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx> >> >> Add support for: AD4111, AD4112, AD4114, AD4115, AD4116. >> >> AD411x family ADCs support a VCOM pin. The purpose of this pin is to >> offer a dedicated common-mode voltage input for single-ended channels. >> This pin is specified as supporting a differential channel with VIN10 on >> model AD4116. >> >> AD4111/AD4112 support current channels. Support is implemented using >> single-channel and "adi,current-channel". >> >> Signed-off-by: Dumitru Ceclan <dumitru.ceclan@xxxxxxxxxx> > I like the common-mode-channel solution to the pseudo differential > description. It makes things explicit whilst avoiding an ugly differential > but not differential mess. > > However, it feels like a general thing to me not a vendor specific one. > Perhaps makes sense to put in adc.yaml? > Sure > One other question that is more me being curious and failing to understand > the datasheet than a request to change anything. >> --- >> .../devicetree/bindings/iio/adc/adi,ad7173.yaml | 192 ++++++++++++++++++++- >> 1 file changed, 190 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml b/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml >> index ea6cfcd0aff4..d8474eee553e 100644 >> --- a/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml >> +++ b/Documentation/devicetree/bindings/iio/adc/adi,ad7173.yaml >> @@ -19,7 +19,18 @@ description: | >> primarily for measurement of signals close to DC but also delivers >> outstanding performance with input bandwidths out to ~10kHz. >> >> + Analog Devices AD411x ADC's: >> + The AD411X family encompasses a series of low power, low noise, 24-bit, >> + sigma-delta analog-to-digital converters that offer a versatile range of >> + specifications. They integrate an analog front end suitable for processing >> + fully differential/single-ended and bipolar voltage inputs. >> + >> Datasheets for supported chips: >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4111.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4112.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4114.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4115.pdf >> + https://www.analog.com/media/en/technical-documentation/data-sheets/AD4116.pdf >> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7172-2.pdf >> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7172-4.pdf >> https://www.analog.com/media/en/technical-documentation/data-sheets/AD7173-8.pdf >> @@ -31,6 +42,11 @@ description: | >> properties: >> compatible: >> enum: >> + - adi,ad4111 >> + - adi,ad4112 >> + - adi,ad4114 >> + - adi,ad4115 >> + - adi,ad4116 >> - adi,ad7172-2 >> - adi,ad7172-4 >> - adi,ad7173-8 >> @@ -129,10 +145,54 @@ patternProperties: >> maximum: 15 >> >> diff-channels: >> + description: | >> + This property is used for defining the inputs of a differential >> + voltage channel. The first value is the positive input and the second >> + value is the negative input of the channel. >> + >> + Family AD411x supports a dedicated VINCOM voltage input. >> + To select it set the second channel to 16. >> + (VIN2, VINCOM) -> diff-channels = <2 16> >> + >> + There are special values that can be selected besides the voltage >> + analog inputs: >> + 21: REF+ >> + 22: REF− >> + Supported only by AD7172-2, AD7172-4, AD7175-2, AD7175-8, AD7177-2: >> + 19: ((AVDD1 − AVSS)/5)+ >> + 20: ((AVDD1 − AVSS)/5)− > > That's what it says on the datasheet (so fine to copy that here) but I'm curious, what does > that mean in practice? How can we have negative and postive signals of the difference > between two power supply voltages where I'm fairly sure AVDD1 always greater than AVSS. > I have not tested that as I do not have a model that supports this wired up. If I had to guess they are the same signal but one should be connected to the positive input, one to the negative input...but I could be wrong. > Anyhow, that's a problem for the person reading the datasheet to figure out :) > >> + >> items: >> minimum: 0 >> maximum: 31 >> >> + single-channel: >> + description: | >> + This property is used for defining a current channel or the positive >> + input of a voltage channel (single-ended or pseudo-differential). >> + >> + Models AD4111 and AD4112 support current channels. >> + Example: (IIN2+, IIN2−) -> single-channel = <2> >> + To correctly configure a current channel set the "adi,current-channel" >> + property to true. >> + >> + To configure a single-ended/pseudo-differential channel set the >> + "adi,common-mode-channel" property to the desired negative voltage input. >> + >> + When used as a voltage channel, special inputs are valid as well. >> + minimum: 0 >> + maximum: 31 >> + >> + adi,common-mode-channel: >> + $ref: /schemas/types.yaml#/definitions/uint32 >> + description: >> + This property is used for defining the negative input of a >> + single-ended or pseudo-differential voltage channel. >> + >> + Special inputs are valid as well. >> + minimum: 0 >> + maximum: 31 >> + >
