Julian Appel f60a29137c Fix bootloader hardware bring-up and add key-based boot entry ... Hardware-tested the UF2 bootloader end to end on a real VersaPad v2 board. Found and fixed a real bug: the bootloader's jump into the app (__set_MSP -> SCB->VTOR -> bx) hard-faulted on every standalone boot, even with the debugger fully disconnected; identical register/VTOR values injected directly by a halted debugger ran fine, which pointed at the missing __DSB()/__ISB() barriers ARM's own guidance requires for this exact pattern. Also fixed a USB PID collision (0x0011 is Adafruit's own Gemma M0 bootloader PID, misidentified by Windows as a Circuit Playground COM port instead of exposing VERSABOOT). This board has no dedicated reset/boot button, so add a hardware boot entry that doesn't need one: holding the bottom-right Cherry MX key (key_id 24) during reset/power-on drives its matrix row and reads its column directly in the bootloader, before the app is even validated. Also corrected the app-side flash_with_bootloader.ld (was missing the NVM carve-out flash_without_bootloader.ld already has) and boards/versapad.json (wrong flash/RAM size, wrong MCU macro, stale PID), and enabled the previously-commented-out env:versapad_usb. Documented findings in bootloader/README.md, bootloader/TESTING.md, and doc/09_known_limitations.md. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>		2026-08-05 21:28:15 +02:00
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versapad	Fix bootloader hardware bring-up and add key-based boot entry	2026-08-05 21:28:15 +02:00