Wait, I just may have found the fundamental issue.
Are the MOSI and MISO connections from teensy to prop shield supposed to,be connected? I assumed all the wire connections are just connected to the teensy alone.
So which ones works and which ones do not?
For my issue, I tried all the simple solves first, like using the soundfonts as is, after I modified them, no directories on soundcards etc.
Part of my problem was improper diagnostics in the first few messages. Some of the issues were created from the same root cause, which was the teensy bricking.
Are you triple-darn-sure you have those hooked up right?
I even switched them before I tried another SD card reader , which actually has MOSI and MISO labeled on board as opposed to DI DO etc. I will try switching them again when the iron is hot.
Just to confirm, MOSI=DI which is connected to pad 11 on teensy.
MISO=D0 connected to pad 12.
Ideally you'd use an oscilloscope or a digital analyzer to see what is going on the SD card pins.
If you don't have any of those, you might try a multimeter (set it to AC to check for digital signals)
Also, there are digtal analyzer sketches for arduino/teensy, so you could potentially hook up another teensy or arduino to the relevant pins and run a sketch that lets you see what is going on.
Yes, that was the next step. The monitor is able to show info on accelerometers and such, so I didn't think it could be a propshield communication issue. At this point I am not sure if the MTP transfer is an unrelated issue or not. I will try the rawfile uploader sketch.
Perhaps one of the teensy to prop shield pins doesn't have a perfect connection, but my soldering is usually pretty good. If I find a misbehaving Pin, I will see which one is best to use as backup.
Rebooting the teensy typically doesn't help. Only removing the sd card or cutting the power actually helps
I had been pulling the blade typically. The teensy has no problem being recognized by the computer, and if there is not a SD card inserted, I can get serial monitor everytime.
I might try and dismantle the unit and try again from scratch, while I put together the 3.6. I dislike that idea, as I risk mucking up the pads if I'm hasty.