boards: sparkfun: Fix sparkfun_pro_micro_rp2040 gpiomap

[ulmanyar]

The SparkFun Pro Micro pins are numbered 1, 0, GND, ... from top left whereas the SparkFun Pro Micro RP2040 and the RP2040 Community Edition boards are numbered 0, 1, GND, ... , so the pro_micro: connector gpio-map should reflect that.

Graphical Datasheet for SparkFun Pro Micro RP2040: https://cdn.sparkfun.com/assets/e/2/7/6/b/ProMicroRP2040_Graphical_Datasheet.pdf

Graphical Datasheet for SparkFun Pro Micro:
https://cdn.sparkfun.com/assets/f/d/8/0/d/ProMicro16MHzv2.pdf

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[soburi]

Hi, @ulmanyar

The pro-micro connector is defined here,

zephyr/dts/bindings/gpio/sparkfun-pro-micro-header.yaml

Lines 17 to 30 in ad7086a

	This binding provides a nexus mapping for 18 pins, as depicted below:
	0 TX0 RAW -
	1 RX1 GND -
	- GND RST -
	- GND VCC -
	2 D2 D21/A3 21
	3 D3 D20/A2 20
	4 A4 D19/A1 19
	5 D5 D18/A0 18
	6 D6 D15 15
	7 D7 D14 14
	8 D8 D16 16
	9 D9 D10 10

but from this definition the settings before the change are correct.

[ulmanyar]

The more I look at this, the more it seems like a game of telephone where inconsistencies propagate and multiply.

I would argue that the pro-micro connector definition you linked is incorrect, as I think it should reflect the pins of the original Pro Micro. I will add that to this PR.

I also looked at what boards are using this, and it seems it's only the SparkFun Pro Mirco RP2040 that I originally addressed, but also the Adafruit KB2040 so I can add that as well.

As a side note: in the naming of the KB2040 pins, they have labeled D0 and D1 as "CircuitPython Name", whereas Sparkfun Pro Micro label them as "Arduino", and I don't know if they are supposed to be 1:1 or not. I have never worked with CircuitPython, but in practice they do not seem to be 1:1 based on:
https://github.com/adafruit/circuitpython/blob/54e78c89fc9e0d2b31544dfd03c30a159e8540a4/ports/raspberrypi/boards/sparkfun_pro_micro_rp2040/pins.c#L25
https://github.com/adafruit/circuitpython/blob/ad6bc74f28fcfc8cfa656122f62ba27495721dc5/ports/raspberrypi/boards/adafruit_kb2040/pins.c#L17

[ulmanyar]

Any additional feedback on this? This was merged downstream in ZMK but it would be great to be able to use the board from Zephyr directly.

[fabiobaltieri]

if there's two versions of the number it may be a good idea to make the description here reflect that

[ulmanyar]

See comment below. I think this is the only variant in Zephyr.

[fabiobaltieri]

Cool, then maybe add a comment after the table here describing that the first two pins are swapped on some boards and that this binding is used for both variants?

[ulmanyar]

I realised I could be clearer: This documentation describes the (original) SparkFun Pro Micro header and its corresponding pin numbers. In that original header, the order is 1, 0, GND, ...

Each Pro Micro-compatible board--such as SparkFun Pro Micro RP2040 which n.B. is a different board, or any board that wants to be Pro Micro-compatible--then defines a gpio_map that maps that board's pinout to the header described here so that shields can be defined using the &pro_micro pins and seamlessly be used with any Pro Micro-compatible board.

So in my opinion, it does not make sense to add every compatible board in this header description, as they are really not variants, but unique boards with compatible pinouts. I hope this clarifies the confusion I made!

[fabiobaltieri]

Ok I see what you are saying now, sorry https://cdn.sparkfun.com/assets/e/2/7/6/b/ProMicroRP2040_Graphical_Datasheet.pdf got me really confused about the whole story.

[fabiobaltieri]

Actually, could you add a link to https://cdn.sparkfun.com/assets/f/d/8/0/d/ProMicro16MHzv2.pdf in this file maybe? Just for convenience, doubt that url will go anywhere anyway.

[ulmanyar]

There, fixed a few minor things (inconsistent use of both Dx/Ay and only Dx, as well as a typo where TX0 became TX0, and RXI became RX1), and added the link. This should be ready for merge now?

[fabiobaltieri]

cc @petejohanson

[soburi]

The more I look at this, the more it seems like a game of telephone where inconsistencies propagate and multiply.

I would argue that the pro-micro connector definition you linked is incorrect, as I think it should reflect the pins of the original Pro Micro. I will add that to this PR.

I also looked at what boards are using this, and it seems it's only the SparkFun Pro Mirco RP2040 that I originally addressed, but also the Adafruit KB2040 so I can add that as well.

As a side note: in the naming of the KB2040 pins, they have labeled D0 and D1 as "CircuitPython Name", whereas Sparkfun Pro Micro label them as "Arduino", and I don't know if they are supposed to be 1:1 or not. I have never worked with CircuitPython, but in practice they do not seem to be 1:1 based on: https://github.com/adafruit/circuitpython/blob/54e78c89fc9e0d2b31544dfd03c30a159e8540a4/ports/raspberrypi/boards/sparkfun_pro_micro_rp2040/pins.c#L25 https://github.com/adafruit/circuitpython/blob/ad6bc74f28fcfc8cfa656122f62ba27495721dc5/ports/raspberrypi/boards/adafruit_kb2040/pins.c#L17

I checked some external connector definitions, and this modification seems to work fine. As @fabiobaltieri pointed out, please update the documentation.

[github-actions]

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