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Grand Central with NeoPxl8
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Grand Central with NeoPxl8

by DavidNeptune on Tue Mar 16, 2021 9:51 pm

It appears that there's little to no documentation on using the Neopxl8 Feather breakout or the Neopxl8 Friend with a Grand Central. I believe I've completely exhausted google at this point. The only relevant forum post appears to be this: viewtopic.php?f=63&t=156708&p=772999&hilit=grand+central+neopxl8#wrap And it never got a conclusive answer.

The product page for the NeoPxl8 Friend specifically says "The library runs on any of our ATSAMD21 (M0) and ATSAMD51 (M4) board" however the comments within the Neopxl8 library code regarding pins doesn't mention the Grand Central at all.

Is there a definitive answer for what pins would work for the Grand Central? It seems like all other M4 boards are spelled out pretty plainly.

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Re: Grand Central with NeoPxl8

by adafruit_support_mike on Thu Mar 18, 2021 11:00 pm

I can't see a list of pins for the M4, but you can cross-reference them by pin numbers.

The mandatory pins are (in order) PA23, PA22, PA21, and PA20. On the Grand Central, those are D7, D6, D5, and D4.

The recommended pins for the last four signals are (in order) PA17, PA16, PA19, and PA18. On the Grand Central, those are D36, D37, D34, and D35.

The alternate pins for the last four signals are (in order) PB16, PB17, PA12, and PA13. On the Grand Central, those are D14, D15, D26, and D27.

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Re: Grand Central with NeoPxl8

by DavidNeptune on Thu Mar 18, 2021 11:05 pm

adafruit_support_mike wrote:
The mandatory pins are (in order) PA23, PA22, PA21, and PA20. On the Grand Central, those are D7, D6, D5, and D4.

The recommended pins for the last four signals are (in order) PA17, PA16, PA19, and PA18. On the Grand Central, those are D36, D37, D34, and D35.

The alternate pins for the last four signals are (in order) PB16, PB17, PA12, and PA13. On the Grand Central, those are D14, D15, D26, and D27.


Thank you so much! I'll wire it up and report back asap.

DavidNeptune
 
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Re: Grand Central with NeoPxl8

by DavidNeptune on Tue Mar 23, 2021 7:58 pm

It appears that I'm still experiencing some issues with this setup. I currently have pins 7, 6, 5, 4, 36, 37, 34, 35 on the Grand Central connected to a feather format Neopxl8 on what would be pins 5, 6, 9, 10, 12, 13, 11, SCK respectively. From my understanding, these pins on the neopxl8 should be fine to use.

Any strips being driven off of 37, 34, and 35 are fine and work properly. Anything driven by pins 7, 6, 5, 4, and 36 do not function and instead are lit up seemingly at random.

The pin declarations are exactly: int8_t pins[8] = { 7, 6, 5, 4, 36, 37, 34, 35 };

Is something wrong with my setup?

DavidNeptune
 
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Re: Grand Central with NeoPxl8

by adafruit_support_mike on Wed Mar 24, 2021 8:47 pm

Hmm.. looks like I swapped documents while cross-referencing the pins. The port-pin designations are all correct: PA23, PA22, PA21, and PA20 are mandatory. PA17, PA16, PA19, and PA18 are recommended. The alternates are (in order from the library's .cpp file) PB17, PB16, PA13, and PA12.

Using those references to look up pins in the Grand Central's variant.cpp file, they map like so:

Code: Select all | TOGGLE FULL SIZE
    PA23 -> D30
    PA22 -> D31
    PA21 -> D32
    PA20 -> D33

    PA17 -> D36
    PA16 -> D37
    PA19 -> D34
    PA18 -> D35

    PB17 -> D15
    PB16 -> D14
    PA13 -> D27
    PA12 -> D26
The mandatory pins I listed earlier were completely wrong, but the others seem to be correct.

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Re: Grand Central with NeoPxl8

by DavidNeptune on Wed Mar 31, 2021 11:38 pm

I got everything working! Thanks for all the support.

For anyone reading this in the future, you can copy paste either of these, or any blend of the two.

Code: Select all | TOGGLE FULL SIZE
int8_t pins[8] = { 30, 31, 32, 33, 36, 37, 34, 35 };

int8_t pins[8] = { 30, 31, 32, 33, 15, 14, 27, 26 };

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Re: Grand Central with NeoPxl8

by adafruit_support_mike on Thu Apr 01, 2021 5:34 pm

Glad to hear you got things working. Thanks for posting the follow-up!

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Please be positive and constructive with your questions and comments.