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NeoPXL8 FeatherWing and Feather M0 LoRa
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Please be positive and constructive with your questions and comments.

NeoPXL8 FeatherWing and Feather M0 LoRa

by mh512 on Tue Aug 25, 2020 4:58 pm

Hi All

I've just purchased a Feather M0 with RFM95 LoRa Radio (https://www.adafruit.com/product/3179) and Adafruit NeoPXL8 FeatherWing (
Code: Select all | TOGGLE FULL SIZE
https://www.adafruit.com/product/3249
) and having read the learning guides, am in need of some reassurance before I embark on the project!

I know that he NeoPXL8 wing makes use of some fixed pins on the M0 that are unable to be configured (like some of the other pins) and I'm concerned that these will play havoc with the pins the LoRa radio requires.

I think though, that it is possible for me to get both the LoRa radio and the NeoPXL8 wing both working - is anyone able to confirm please?

As well as the neopixels, I need 4 other I/O pins for digital output in my project.

Thanks.
mh512
 
Posts: 64
Joined: Wed Nov 13, 2013 4:06 pm

Re: NeoPXL8 FeatherWing and Feather M0 LoRa

by mikeysklar on Tue Aug 25, 2020 5:26 pm

This will be a little tricky as the M0 RFM95 is going to want to use SPI to talk to the Radio and he NeoPXL8 is also going to want SPI. Sharing multiple devices on the same SPI bus is normally fine, but it means you need to use a CS pin to toggle control between teh NeoPXL8 and RFM95. So it is doable, but there will be trade offs such as not being able to have the radio always receiving / transmitting.

We do have a guide that uses a M0 RFM69 and NeoTrellis controller for a wireless NeoPixel setup.

https://learn.adafruit.com/neotrellis-n ... r/overview

Also some details about the M0 NeoPXL8 pin compatibility concerns:

https://learn.adafruit.com/adafruit-neo ... eatherwing

mikeysklar
 
Posts: 1943
Joined: Mon Aug 01, 2016 8:10 pm

Re: NeoPXL8 FeatherWing and Feather M0 LoRa

by mh512 on Tue Aug 25, 2020 5:39 pm

Thanks, understood.

If I were to only use the NeoPXL8 wing to control 3 NeoPixel strips would that help?

The guide says that for the M0 only outputs 3, 6 and 7 are fixed to specific Feather pins (13, A4, A3) and I can't see from the M0 LoRA pinout that these pins are required for the radio.

Would I be able to set (in code) all the pins for the other outputs to -1 to free up the conflicting pins for the radio?
mh512
 
Posts: 64
Joined: Wed Nov 13, 2013 4:06 pm

Re: NeoPXL8 FeatherWing and Feather M0 LoRa

by mikeysklar on Wed Aug 26, 2020 11:04 am

Controlling 3 NeoPixel strips or 4 should not make a difference unless you are encountering memory limitation issues which is possible with the M0.

I see the GPIOs available to you to drive NeoPixels with no conflicts are 5, 6, 10, 11 and 12. I would set aside pin #8 for use with the CS control. The #8 pin (CS) would be the one to toggle high when not using the radio.

https://learn.adafruit.com/adafruit-fea ... le/pinouts

#5 - GPIO #5
#6 - GPIO #6
#10 - GPIO #10
#11 - GPIO #11
#12 - GPIO #12


Screen Shot 2020-08-26 at 7.54.08 AM.png
Screen Shot 2020-08-26 at 7.54.08 AM.png (1.54 MiB) Viewed 19 times

mikeysklar
 
Posts: 1943
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Re: NeoPXL8 FeatherWing and Feather M0 LoRa

by mh512 on Sun Aug 30, 2020 4:41 pm

Thanks, sorry still a bit confused.

If I'm only using outputs 3, 6 and 7 I only require pins 13, A4, A3 of the M0.

These pins aren't used for the radio so I'm not sure why there'd be a conflict.

I'm going to need the radio to be 'listening' all the time.

Thanks,
Max
mh512
 
Posts: 64
Joined: Wed Nov 13, 2013 4:06 pm

Re: NeoPXL8 FeatherWing and Feather M0 LoRa

by mikeysklar on Mon Aug 31, 2020 7:21 pm

If the NeoPXL8 is using SPI and the Radio is using SPI you will need to share the bus which means the radio will need to be turned off by pulling the CS pin high while communicating with the NeoPXL8. So radio listening all the time will be a problem.

Otherwise the pins you want to use are fine.

mikeysklar
 
Posts: 1943
Joined: Mon Aug 01, 2016 8:10 pm

Please be positive and constructive with your questions and comments.