Selecting Boot Device Print

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

  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: