.. zephyr:board:: stm32mp257f_dk

Overview

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The STM32MP257F-DK Discovery kit is designed as a complete demonstration and development platform for the STMicroelectronics STM32MP257F microprocessor based on Arm® dual-core Cortex®-A35 (1.5 GHz) and Cortex®-M33 (400 MHz), and the STPMIC25 companion chip. Zephyr OS is ported to run on the Cortex®-M33 core, as a coprocessor of the Cortex®-A35 core.

Features:

• STM32MP257FAI3 microprocessor featuring dual-core Arm® Cortex®-A35, a Cortex®-M33 in a VFBGA424 package

• ST power management STPMIC25

• 32‑Gbit LPDDR4 DRAM

• 64-Gbit eMMC v5.1

• 1‑Gbit/s Ethernet (RGMII)

• Two USB 2.0 high speed

• USB 3.0 SuperSpeed PD (DRP/DRD)

• Wi‑Fi® 802.11b/g/n

• Bluetooth® LE

• Four user LEDs

• Two user, one tamper, and one reset push-buttons

• Wake-up button

• Four boot pin switches

• Board connectors:

  • Ethernet RJ45
  • Two stacked USB 2.0 HS Type-A
  • USB 3.0 USB Type-C® PD
  • microSD™ card holder
  • Dual-lane MIPI CSI-2® camera module expansion connector
  • HDMI®
  • LVDS
  • GPIO expansion connector
  • VBAT for power backup

• On-board STLINK-V3EC:

  • Debugger with USB re-enumeration capability: Virtual COM port and debug port
  • Board power source through USB Type-C®

• Mainlined open-source Linux® STM32 MPU OpenSTLinux Distribution and STM32CubeMP2 software with examples

• Linux® Yocto project®, Buildroot, and STM32CubeIDE as development environments

More information about the board can be found at the STM32MP257F-DK website_.

Hardware

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• Cores

  • 64-bit dual-core Arm® Cortex®-A35 with 1.5 GHz max frequency
  • 32-bit Arm® Cortex®-M33 with FPU/MPU, Arm® TrustZone®, and 400 MHz max frequency

• Memories

  • External DDR memory up to 4 Gbytes
  • 808-Kbyte internal SRAM
  • Two octo-spi memory interfaces
  • Flexible external memory controller with up to 16-bit data bus

• Power

  • STPMIC25 for voltage regulation (multiple buck/LDO regulators)
  • USB-C power input

• Clock management

  • 32.768 kHz LSE crystal
  • 40 MHz HSE crystal
  • Internal 64 MHz HSI oscillator
  • Internal 4 MHz CSI oscillator
  • Internal 32 kHz LSI oscillator
  • Five separate PLLs with integer and fractional mode

• Security/Safety

  • Secure boot, TrustZone® peripherals, active tamper, environmental monitors, display secure layers, hardware accelerators
  • Complete resource isolation framework

• Connectivity

  • 1x Gigabit Ethernet (RGMII)
  • USB 2.0 High-Speed Host (dual-port)
  • USB Type-C® DRP
  • GPIO expansion connector

• Display & Camera

  • LVDS interface (4-lane)
  • Camera CSI-2 interface (2-lane)

• Debug

  • STLINK-V3EC (onboard debugger with VCP, JTAG and SWD)

More information about STM32MP257F can be found here:

• STM32MP257F on www.st.com_

Supported Features

.. zephyr:board-supported-hw::

Connections and IOs

STM32MP257F-DK Discovery kit schematic is available here: STM32MP257F-DK Discovery kit schematics_

System Clock

Cortex®-A35

Not yet supported in Zephyr.

Cortex®-M33

The Cortex®-M33 Core is configured to run at a 400 MHz clock speed.

Programming and Debugging

---

.. zephyr:board-supported-runners::

Prerequisite

Before you can run Zephyr on the STM32MP257F-DK Discovery kit, you need to set up the Cortex®-A35 core with a Linux® environment. The Cortex®-M33 core runs Zephyr as a coprocessor, and it requires the Cortex®-A35 to load and start the firmware using remoteproc.

One way to set up the Linux environment is to use the official ST OpenSTLinux distribution, following the Starter Package. (more information about the procedure can be found in the STM32MPU Wiki)

Loading the firmware

Once the OpenSTLinux distribution is installed on the board, the Cortex® -A35 is responsible (in the current distribution) for loading the Zephyr firmware image in DDR and/or SRAM and starting the Cortex®-M33 core. The application can be built using west, taking the :zephyr:code-sample:blinky as an example.

.. zephyr-app-commands:: :zephyr-app: samples/basic/blinky :board: stm32mp257f_dk/stm32mp257fxx/m33 :goals: build

The firmware can be copied to the board file system and started with the Linux remoteproc framework. (more information about the procedure can be found in the STM32MP257F boot Cortex-M33 firmware_)

Debugging

Applications can be debugged using OpenOCD and GDB. The OpenOCD files can be found at device-stm-openocd_. The firmware must first be started by the Cortex®-A35. The debugger can then be attached to the running Zephyr firmware using OpenOCD.

• Build the sample:

.. zephyr-app-commands:: :zephyr-app: samples/basic/blinky :board: stm32mp257f_dk/stm32mp257fxx/m33 :goals: build

• Copy the firmware to the board, load it and start it with remoteproc (STM32MP257F boot Cortex-M33 firmware_). The orange LED should be blinking.
• Attach to the target:

.. code-block:: console

$ west attach

References

.. target-notes::

.. _STM32MP257F-DK website: https://www.st.com/en/evaluation-tools/stm32mp257f-dk.html#overview

.. _STM32MP257F-DK Discovery kit User Manual: https://www.st.com/resource/en/user_manual/um3385-discovery-kit-with-stm32mp257f-mpu-stmicroelectronics.pdf

.. _STM32MP257F-DK Discovery kit schematics: https://www.st.com/resource/en/schematic_pack/mb1605-mp257f-c01-schematic.pdf

.. _STM32MP25xC/F Discovery kit datasheet: https://www.st.com/resource/en/datasheet/stm32mp257c.pdf

.. _STM32MP257F on www.st.com: https://www.st.com/en/microcontrollers-microprocessors/stm32mp257f.html

.. _STM32MP257F reference manual: https://www.st.com/resource/en/reference_manual/rm0457-stm32mp25xx-advanced-armbased-3264bit-mpus-stmicroelectronics.pdf

.. _STM32MP257F boot Cortex-M33 firmware: https://wiki.st.com/stm32mpu/wiki/Linux_remoteproc_framework_overview#Remote_processor_boot_through_sysfs

.. _Starter Package: https://wiki.stmicroelectronics.cn/stm32mpu/wiki/STM32MP25_Discovery_kits_-_Starter_Package

.. _STM32MPU Wiki: https://wiki.st.com/stm32mpu/wiki/Main_Page

.. _device-stm-openocd: https://github.com/STMicroelectronics/device-stm-openocd/tree/main