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Unused Digital Pins

Posted by donhuevo 
Unused Digital Pins
May 22, 2014 01:53PM
I want to use an available digital pin to control a neopixel RGB LED. Looking at the RAMPS 1.4 schematic, in the AUX2 area, I see D40, D42 & D44 may be available. Trying to decipher pins.h knowing I have motherboard 33 to be sure these are available and I can't seem to find a definitive answer. I've hooked up to D44 and didn't get expected results.

My question is, given that I have motherboard 33 and a reprap discount LCD, what are my options for an available digital pin?
Re: Unused Digital Pins
May 23, 2014 01:12AM
Its not that easy

that device requires some very specific timings, which will interfear with normal ramps operation.

They normaly require a dedicated micro of their own.
Re: Unused Digital Pins
May 23, 2014 10:28AM
Hi Dust. Thanks for the quick reply. I know this isn't the first time you've had to tell someone this. I've also posted this issue in Adafruit's forums asking if anything can be done with neopixel timing to get it to play nice. I know it's a longshot. In the meantime, given my motherboard, are D40, D42 & D44 actually available?

I found //#define TEMP_STAT_LEDS in configuration.h and followed it to the manage_inactivity function in Marlin_main and ultimately the handle_status_leds function also in Marlin_main. I wrote something up paralleling that specifically for the neopixel, added the Adafruit_neopixel libraries to the mix and got it to compile. I used pin D44, hardcoded the color blue but I got a blinky salmon (probably the timing issue but I'm still not sure if 44 is truly free and available). I've attached a mockup of where I'd ultimately like to end up.
open | download - neopixel_E3d_test.JPG (41.8 KB)
Re: Unused Digital Pins
May 24, 2014 03:29PM
So here's what I learned... The 5V in the AUX2 group of pins isn't 5V but both 5V pins in AUX1 are. I'm pulling 5V from AUX1 & still using D44 from AUX2. The 'blinky' was coming from having less than 5V. The salmon was because I had a mistake in my math. It's working fine now. I have my led function being called from within the manage_inactivity function in Marlin_main. No issues with interrupts that I can see, the light is red and it's currently printing at 150%. I think we're good!
Re: Unused Digital Pins
May 30, 2014 10:09PM
It's boring but here's a video of my hot end heating up...
Neopixel displaying temp
Re: Unused Digital Pins
November 28, 2014 10:23AM
A quick tutorial... [forums.adafruit.com]
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