diff --git a/board/aarch64/README.md b/board/aarch64/README.md index 580b25a4..0b869b56 100644 --- a/board/aarch64/README.md +++ b/board/aarch64/README.md @@ -12,3 +12,48 @@ FIT options: make board-enable-sparx-fit +### Unbricking + +1. Don't load a corrupt bootloader to begin with +2. Done + +If, for some reason, you didn't manage to follow step 1, you can use +the `FLASH_PROG`(`J4`) connector on the board to access the SPI flash +directly. + +Using a [Bus Blaster][BB3] in combination with [dangerspi][dangerspi], +you can load a new bootloader. The schematic below details how to +connect the Bus Blaster to the board, but the concept should be +portable to any debugger/device based around an FTDI2232 chip. + +``` +Bus Blaster: FLASH_PROG (J4): + .---. .---. + VTG >o o| VTG SCK >o o| GND + TRST |o o| GND MISO |o o| #RESET_FLASH + TDI |o o| GND o o| 3V3 + TMS |o o| GND #CS |o o| #SYSRESET + TCK o o| GND MOSI |o o| GND + RTCK o o| GND '---' + TDO |o o| GND + TSRST |o o| GND + DBGRQ |o o| GND +DBGACK |o o| GND + '---' +``` + +| Bus Blaster | FLASH_PROG | +|-------------|----------------| +| `VTG` | `3V3` | +| `GND` | `GND` | +| | | +| `VTG` | `#RESET_FLASH` | +| `GND` | `#SYSRESET` | +| | | +| `TDI` | `MOSI` | +| `TMS` | `#CS` | +| `TCK` | `SCK` | +| `TDO` | `MISO` | + +[BB3]: http://dangerousprototypes.com/docs/Bus_Blaster#Bus_Blaster_v3 +[dangerspi]: https://github.com/wkz/dangerspi