Repurpose unused pin for WS2812 Duet2

Topher

I see there is support for addressable LEDs for duet 3 using its dedicated LED port. Is it possible to use an empty pin from the Duet2 and repurpose it for a dotstar data pin?

Thanks in advance

dc42

I think you mean Neopixel, not DotStar. To drive a Neopixel string efficiently, you need to use an unused SPI channel. I think all the ones available on Duet 2 are already in use.

Topher

Oh yes, sorry, I meant NeoPixel/DotStar pin I saw it can be configured for either. So there is no possibility to reassign a digital or pwm pin? Similar to how it could be done with marlin?

droftarts

@LeckieTech see this thread, which has a number of different ways to set them up: https://forum.duet3d.com/topic/13600/how-can-i-control-addressable-rgb-leds/

Ian

dc42

My guess is that Marlin suspends everything else when you write to Neopixel LEDs. I think you will find that if you command the LEDs while printing, it pauses the print briefly.

On Duet 3 and 3 Mini we use a dedicated SPI channel with DMA to drive Neopixel LED strips.

There are threads on this forum about using an Arduino connected to the Duet to control Neopixel strips.

Topher

Oh yes, I have searched before posting this and did see it could be done with an Arduino but I was hoping for a more efficient wiring solution for my project since I have 60 printers to upgrade. The printer pausing wouldn't be a problem for me as I would only be sending data to the LED strip via M150 when the operations change (filament change, heating/cooling hot end/bed, printer ready/print in progress, etc). The whole purpose of the lights would be to have different color codes so they stand out on the rack at a glance when they need attention. Too many times I've walked by printers that have not been printing for hours because they'd finished or run out of filament and paused! I would still be interested if it is possible!

droftarts

@LeckieTech Do you need to use NeoPixels? Do you need more than one status light on at a time, showing different colours? If not, you can use a 4-wire RGB LED strip (or just one LED), wire the three LED PWM channels to spare heater pins (eg on the expansion connector if you don't have Duex5 board) and control the PWM to each fan channel to control the colour. See @appjaws post here: https://forum.duet3d.com/post/134969

Not sure how to do it using SPI. However, there are accessible SPI pins on the temperature daughterboard connector, PanelDue ribbon cable connector and expansion pins, so if you're not using one of those, maybe look to use one of those? See wiring diagram for location: https://duet3d.dozuki.com/Wiki/Duet_Wiring_Diagrams

Ian

Topher

I really wanted to use addressable LEDs, mainly because we already have many of our printers fixed with them running 8bit marlin boards. Were trying to roll out a wifi2 board upgrade with the least amount of labor/parts

zapta

@dc42 said in Repurpose unused pin for WS2812 Duet2:

My guess is that Marlin suspends everything else when you write to Neopixel LEDs. I think you will find that if you command the LEDs while printing, it pauses the print briefly.

@dc42, what is your estimation of the pause necessary to change the color of N WS2812 LEDS connected in serial?

According to the link below, 100 serial LEDs require less than 5ms, shorter than a retraction, and most users may still prefer it over having to attach an Arduino. (I would).

https://blog.ja-ke.tech/2019/06/02/neopixel-performance.html