The Emcraft STM32MP1 Starter Kit supports several boot devices. Selection of a specific boot device is defined by the state of the switches on the SOM-BSB development board, as follows:
SW4.2 | SW4.3 | SW4.4 | |
Boot from SD Card | - | OFF | ON |
Boot from on-module eMMC | - | ON | OFF |
Boot from USB Serial Downloader | - | OFF | OFF |
Boot in Debug engineering mode | OFF | ON | ON |
Hardware Modifications for Boot in Debug Engineering Mode
Connect a 1k...3.3k resistor between +3.3V and S4 pin 2 (S4.2). The closest +3.3V points are the following:
U8.1 = C18.2
R16.2 (the farthest pin from S4)
Connect with a wire S4.2 to P2.1.
By default, the Starter Kit is configured to boot the default Linux configuration from the on-module eMMC. You can override this configuration by modifying the set of the switches on the SOM-BSB, as described above.
Refer to the following additional information on how to boot from the various devices:
Booting from USB Serial Downloader.