Hacking my motes


#1

So… the mote sticks are too big to fit on my current project. I saw the thread about cutting mote sticks and may resort to doing that, but then I thought “Mote sticks are just APA102s, so I could wire up my own strip of these and run them off the mote controller!” So I sliced up a USB cable and wired it to a strip of APA102 LEDs, as shown:


The problem is, when I plug in the USB Mote Controller, a random selection of the LEDs on the strip light up, then stay lit up whatever I do. Here’s an example of running rainbow.py from the examples, showing the proper mote sticks behaving properly, but not the APA102 strip:

While the mote sticks cycle through the rainbow happily, the strip stays static. And it doesn’t matter which port on the controller board I plug it in to…

Any ideas what I might be doing wrong?


Longer LED strips for MOTE
#2

Your assumptions are correct- I’ve got a Blinkt! somewhere which I successfully wired into Mote.

The pinout is detailed - poorly in retrospect - here. If you’ve been doing it by sheer force of genius up to this point it might help: http://docs.pimoroni.com/mote/#lighting-ports

VCC/GND are clearly working- although these LEDs are infamous for leeching power from the data lines, you’d notice if that was happening by the fact you can still see.

My guess would be that either the data/clock lines are reversed, or the soldering is just a little tenuous. I’m trying to wrap my brain around the pinout to see if might be the latter, but it’s too Monday morning for me to succeed just yet.

Also worth noting that them lighting up is probably due to electrical noise.

And also, is it my eyes/the angle or are there two different die types in those pixels? The first and fourth die’s look darker.


#3

Thanks for some ideas to consider - I’ll have a look when I get home this evening. A day of teaching about implementing scalar optimisations in compilers first! As I said on twitter, I’m fairly sure I’ve got the soldering right, as I’ve redone it several times and keep getting the same outcomes. But there’s definitely something wrong - I’ve also tried wiring up a shorter length to SPI0 and it’s not behaving properly, so maybe I’ve got a dodgy strip, but I think it’s far more likely that I’m doing something wrong. There’s a lot more about this on my blog https://glitterator.wordpress.com/2017/02/27/a-frustrating-weekend/ but probably not any useful new information.


#4

Woohoo! It was data and clock round the wrong way. Wire colours in USB do not correspond to wire colours used in supplied connectors. (From USB I have green connected to clock, white to data; supplied wiring had yellow to clock, green to data.) With this I get pretty rainbows: https://youtu.be/Vw9j6i04GAU