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STM32MP135F-DK

Board Identification

Identifier: STM32MP135F-DK

Yocto MACHINE:

  • stm32mp13-disco-welma

Documentation:

Features:

  • MPU: STM32MP135f ARM Cortex‑A7 32-bit
  • RAM: up to 1 GB DDR
  • Storage: microSD
  • RJ45 Ethernet
  • Two Quad-SPI memory interfaces
  • 1-Gbit/s Ethernet (RGMII)
  • 4 USB Host Type-A
  • Dual-lane MIPI CSI-2 camera module expansion connector

Boot Sequence

The boot sequence from an SD card is as follows:

  • The ROM Code loads TF-A (BL2, FSBL) from the first GPT partition (raw) into SRAM (System RAM inside MPU), and starts it.
  • TF-A:
  • Initializes DRAM (used in the following steps)
  • Loads the FIP container (SSBL) from the partition named "fip"
  • Launches OP-TEE (BL32)
  • OP-TEE launches U-Boot (BL33) (in DRAM)
  • U-Boot starts the kernel
  • The kernel mounts the initial ram file system (initramfs) and starts Init

Reference: Trusted Firmware-A

Glossary:

  • FSBL: First Stage Boot Loader
  • SSBL: Second Stage Boot Loader
  • DRAM: Dynamic RAM, external to the MPU
  • TF-A: Trusted Firmware-A

First installation

  • On a PC, copy the generate SD card image (.wic) file to the SD card:
$ SDIMG=tmp/deploy/images/$MACHINE/welma-image-minimal-dev-$MACHINE.wic
$ gunzip --keep --force $SDIMG.gz
$ sudo dd if="$SDIMG" of=/dev/mmcblk0 bs=1M
  • Insert the SD card into the device.
  • Your device is ready for booting Welma.

Regular Boot

The regular boot on a SD card is done as follows:

  • Insert a programmed SD card
  • Set the boot pins (SW1) to select the boot source SDMMC1 (used by the internal boot ROM):
    • BOOT0 = 1 (closed)
    • BOOT1 = 0 (open)
    • BOOT2 = 1 (closed)
  • Start the board.

Appendix

Connecting the board (power in & serial)

To power the board, connect its USB Type-C connector CN12 to a 5 V / 3 A USB Type-C charger.

To get a console, connect its micro-USB connector CN10.

Top side

Connecting to the board via IP/Ethernet

  • Connect a cable between your PC and the board (ETH1).

  • Set up a network interface on your PC (say eth0).

By default, Welma Linux has 2 default static link-local IP addresses : 169.254.0.1 and fe80::1.

  • Connect using ssh:
$ ssh root@fe80::1%eth0

Hardware watchdog

The hardware watchdog is:

  • Started by U-Boot (timeout 32 s)
  • Serviced by the Linux kernel (as long as no userspace process opens /dev/watchdog0 and takes over)
  • Then serviced by systemd