I'm trying to write a Rust USB FS device driver for the LPC55S6x chips, using the LPC55S69-EVK board.
I'm using gdb to connect via JLinkGDBServer to a J-Link OB.
Following section 41.3 of UM11126, I'm trying to set DEV_ENABLE in the USBFSH PortMode register. This fails, and I can't even read out the value of this bit. Instead JLinkGDBServer starts losing connection to the device.
Is there any known reason why reading and writing the portmode might fail? Possibly some detail specific to the EVK board?
To make matters worse, I can no longer connect at all:
Connecting to target...ERROR: InitTarget(): PCode returned with error code -1
ERROR: Could not connect to target.
And even mass erasing flash via JFlashLite with J10 set fails.
So while I wait for a replacement board, any pointers are very much appreciated.