boards: shields: Adding Adafruit 5x5 Neopixel Grid BFF

[raveious]

The Adafruit 5x5 NeoPixel Grid BFF is a little shield for any of the Xiao compatible boards with a 5x5 grid of WS2812B RGB LEDs on the back.

[raveious]

@soburi @simonguinot Would you two mind reviewing this?

[raveious]

@soburi @simonguinot Any thoughts on this one?

[simonguinot]

Hi @raveious,

First I apologize for the delay.

This PR looks good to me and except a typo (see my comment below) I don't have much to say.

But don't you want to wait for #68614 to be merged ? So you could add matrix support as well ?

[raveious]

Hi @raveious,

First I apologize for the delay.

This PR looks good to me and except a typo (see my comment below) I don't have much to say.

But don't you want to wait for #68614 to be merged ? So you could add matrix support as well ?

I think the answer is "Yes", but both of our PRs seemed to be stuck.

[raveious]

@soburi Do you have any guidance as to how I can add support for your matrix driver from #68614 ? Is it really just adding the matrix display option to the chosen section?

[soburi]

@raveious

@soburi Do you have any guidance as to how I can add support for your matrix driver from #68614 ? Is it really just adding the matrix display option to the chosen section?

This PR is the first user!

This module may work with this patch and #68614 changes.
Could you try it, please?

0001-bff_display.patch

And build and flush the west build -p -b adafruit_qt_py_rp2040 -d ../qt_py samples/drivers/display/ -- -DSHIELD=adafruit_neopixel_grid_bff_display

[raveious]

@raveious

@soburi Do you have any guidance as to how I can add support for your matrix driver from #68614 ? Is it really just adding the matrix display option to the chosen section?

This PR is the first user!

This module may work with this patch and #68614 changes. Could you try it, please?

0001-bff_display.patch

And build and flush the west build -p -b adafruit_qt_py_rp2040 -d ../qt_py samples/drivers/display/ -- -DSHIELD=adafruit_neopixel_grid_bff_display

So I tried out your changes this morning and everything seems to be working as intended. I did have to add start-from-right and circulative to the device tree based on how the LEDs are oriented on the board.

I do have one request though. Can you add some kind of "power limit" to the driver? These LEDs can take up a lot of power, and I was concerned about how hot the PCB was getting. So if you're planning on using even larger displays then some kind of power limit may be a good idea to implement. One valid implementation would be to rescale the desired values with the new limit, but its ultimately up to you.

Do you think it would be a good idea to just have everything into a single device tree overlay?

If you are curious, I have everything on a new branch that I'll merge/rebase into this one when #68614 gets merged.

[soburi]

@raveious

@soburi Do you have any guidance as to how I can add support for your matrix driver from #68614 ? Is it really just adding the matrix display option to the chosen section?

This PR is the first user!
This module may work with this patch and #68614 changes. Could you try it, please?
0001-bff_display.patch
And build and flush the west build -p -b adafruit_qt_py_rp2040 -d ../qt_py samples/drivers/display/ -- -DSHIELD=adafruit_neopixel_grid_bff_display

So I tried out your changes this morning and everything seems to be working as intended. I did have to add start-from-right and circulative to the device tree based on how the LEDs are oriented on the board.

Great!

I do have one request though. Can you add some kind of "power limit" to the driver? These LEDs can take up a lot of power, and I was concerned about how hot the PCB was getting. So if you're planning on using even larger displays then some kind of power limit may be a good idea to implement. One valid implementation would be to rescale the desired values with the new limit, but its ultimately up to you.

I don't think there is a way to directly limit the current.
However, I believe that this should be achieved through gamma correction.
In other words, the upper bound is rounded down by scaling with a translation table. (Of course, the color resolution will be reduced)
There are several possible implementation methods, but I think piecewise linear implementation is preferable.

Do you think it would be a good idea to just have everything into a single device tree overlay?

If you are curious, I have everything on a new branch that I'll merge/rebase into this one when #68614 gets merged.

I think the display interface is easier to use, so it would be good to integrate it. If anyone doesn't need it, turn off CONFIG DISPLAY to be okay.

[raveious]

I don't think there is a way to directly limit the current. However, I believe that this should be achieved through gamma correction. In other words, the upper bound is rounded down by scaling with a translation table. (Of course, the color resolution will be reduced) There are several possible implementation methods, but I think piecewise linear implementation is preferable.

Maybe less "power limit" and more "brightness limit"?

[soburi]

Maybe less "power limit" and more "brightness limit"?

Yes it is. The higher the brightness of a color, the more power it consumes, so this is a way to limit it.
In reality, there is a non-linear relationship between the brightness setting and the perceived brightness, so implementing gamma correction is good stuff.

[raveious]

@soburi @simonguinot I have rebased this branch to get the changes from #68614. Take a look when you get a chance.

[soburi]

#68514 also merged. You need to rebase this PR.
With this change, you should no longer need to define led-strip in the files inside boards.

[raveious]

#68514 also merged. You need to rebase this PR. With this change, you should no longer need to define led-strip in the files inside boards.

Rebase done. Those files are required because of the dependency on the PIO specific driver.

[soburi]

Wonderful!
Thank you for your continued support.

[simonguinot]

Thanks !