I had some success with Chip's new Spin2 interpreter and PNut's changes to support Spin2... After running several VGA example programs from PNut_v34a, unplugging from my MacBook and replugging into a host Raspberry Pi for power (and back to the MacBook again for re-uploading changes), I've got the red LED lit up and get the dreadful "Could not find a P2 on port /dev/cu.usbserial-..." message from loadp2 or PNut.
I'm fairly certain that I made an effort to unplug the USB cables before plugging or unplugging the Accessory VGA or HDMI boards, to make sure no power was on the pins. But, who knows...
The board shows up on the MacBook as: cu.usbserial-DN43WMDD in the /dev directory, so I know that the FTDI chip is working.
When I also plug the AUX USB into a 5v power source, I am able to use PNut or loadp2 to upload programs. The red LED goes OFF.
Note: the jumpers for LDO VIN 5v & VDD 1V8 are in-place. The jump for ACC HDR 5V is off.
So, what component is most likely blown (voltage regulator? something on the P2 chip itself?)? How do I check? Where to look for voltage, etc...?
Thanks for any insight!