You can create a bootable microSD card and use it to boot the ConnectCore MP25.

The ROM loader of the STM32MP25 can only boot from an SD card using SDMMC1 interface. On the ConnectCore MP25 the SDMMC1 interface is connected to the wireless chip, so wireless variants cannot boot from an SD card.

The microSD socket of the ConnectCore MP25 Development Kit is routed to SDMMC3 so this interface cannot be used to boot, either.

If booting from SD card is a desired feature of your product, you need:

  • a non-wireless variant of the ConnectCore MP25.

  • to connect a microSD socket to SDMMC1 lines on your carrier board.

Create a bootable microSD card

Requirements

  • Root/administrator permissions in your development computer

  • A microSD card with a minimum capacity of 1 GB

Build images suitable for microSD card

Refer to Create bootable sdcard image for information on creating an image for the microSD card. As a result of this process, you’ll create an artifact in the form ccmp2-<ram_size>.wks-<timestamp>-mmcblk.direct.

Program the microSD card

This process formats and erases all contents on the microSD card.

  1. Insert the microSD card on your development PC and note the device node assigned to it.

  2. Run the following command to write the full image to the microSD card:

    $ sudo dd if=ccmp2-<ram_size>.wks-<timestamp>-mmcblk.direct of=<microsd_dev>
$ sync

The microSD card is now ready.

Boot the target from microSD card

The ConnectCore MP25 Development Kit cannot boot from the microSD card (see note above).

  1. Insert the microSD card on a socket connected to SDMMC1 (non-wireless variants only)

  2. Change the boot mode switches to boot from the microSD:

    • BOOT.1: ON

    • BOOT.2: ON

    • BOOT.3: OFF

    • BOOT.4: OFF

  3. Apply power

The target boots from the microSD.