The Emcraft STM32MP1 Starter Kit supports several boot devices. Selection of a specific boot device is defined by the state of the jumpers on the JP10 header of STM32MP1-BSB and switches on the SOM-BSB development board, as described in the following sections.

1. Selecting Boot Device on STM32MP1-BSB

Selection of a specific boot device is defined by the state of the switches on the STM32MP1-BSB development board, as follows:

State ON means presence of a jumper on the corresponding pin of the JP10 header; state OFF means absence of a jumper.

2. Selecting Boot Device on SOM-BSB

Selection of a specific boot device is defined by the state of the switches on the SOM-BSB development board, as follows:

2.1. Hardware Modifications for Boot in Debug Engineering Mode

1. 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)

2. 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:

• -Old-Kits: Booting Linux from SD CardUNDEFINED

• STM32MP1-Old-Kits: Booting Linux from eMMC

• Booting from USB Serial Downloader.