Boot straps¶
Rows on the silkscreen are 2 (top) then 1 (bottom). USB ROM is the same on both boards; normal boot is not.
| Mode | r24 (SD) | r30 (eMMC) |
|---|---|---|
| USB ROM (DFU) | SW2 left, SW1 left | SW2 left, SW1 left |
| Normal boot | SW2 right, SW1 left | SW2 left, SW1 right |
The switch that moves between USB and normal is SW2 on r24 and SW1 on r30.
Power-cycle rule¶
The STM32 samples boot source at power-on. A reset button or reboot does not pick up a new BOOT SEL position. Always remove power, wait a second, reapply.
If Linux never starts¶
- Photograph BOOT SEL.
- Compare to the table for your revision.
- If left in USB ROM, the SoC waits for DFU and will not mount the rootfs.