The pin layout documentation for the beaglebone is sorely lacking. Here is what they have for GPIO’s:
Where is the color legend?
I didn’t want to assume, so I counted all of the yellow stripes - all 65 of them - so I can now properly (still) assume they meant the yellow ones should be used for I/O.
This is too much for a beginner to grasp. I’ve been in IT since the mid 90’s in a support/sysadmin/developer role coming from Arduino, and I still had a lot of problems grasping it.
So looking at the SRM, what improvements do you suggest?
Oh, and make sure you look at the -xM version.
For the BB-xm I was using table 22 on the BB-xm System Reference Manual. What confused me to no end was the 2 GND pins pin 27 and pin 28. Why 2 GND on the same Main Expansion Header? Is it for the 2 different power rails - VIO-1V8 (pin1) and DC 5v (pin2)? is it fatal if you mix them up?
Also are there some website for Test Points on the BB-XM (eg I see TP6 and TP7 on the board) that will verify if it is really fried my new BB-XM and what chips in it were fried?
You are right - for a beginner like me it is a lot to grasp. I don’t mind frying chips and buying another (although whole boards are harder to swallow) so long as I can figure out what dumb thing I did wrong. Reluctant to “buy and fry” again!!!
Why not two grounds? It insures a better connection and it was better than leaving a pin unconnected. I din’t have anything else to put on it. Plus, not knowing exactly what would be plugged into I wanted to make sure it had a good ground. There is only one ground on the board. Signals having the same name are connected together.
The test points should be in the SRM on page 144.
Fry and buy? Why not just fry and we repair.