ST B-G474E-DPOW1

This page is for a port of NuttX to the ST Micro B-G474E-DPOW1 Discovery kit with STM32G474RE MCU. For more information about this board, see:

https://www.st.com/content/st_com/en/products/evaluation-tools/product-evaluation-tools/mcu-mpu-eval-tools/stm32-mcu-mpu-eval-tools/stm32-discovery-kits/b-g474e-dpow1.html

Status

This port boots NuttX through to a functional NSH prompt.

Development Environment

Toolchains

An appropriate ARM toolchain is needed, such as the one built with the customized NuttX buildroot or the ready-made GNU Tools for Arm Embedded Processors.

Debugging

The board incorporates a STLINK-V3E programmer/debugger accessible via the Micro-USB Type B connector.

To debug with OpenOCD and arm-nuttx-eabi-gdb:

• Use ‘make menuconfig’ to set CONFIG_DEBUG_SYMBOLS and CONFIG_DEBUG_NOOPT. To see debug output, e.g., the “ABCDE” printed in __start(), also set CONFIG_DEBUG_FEATURES.

• Build NuttX.

• Flash the code using:

  $ openocd -f interface/stlink.cfg -f target/stm32g4x.cfg -c init \
  -c "reset halt" -c "flash write_image erase nuttx.bin 0x08000000"
  

NOTE: The above command might fail unless either: udev rules have been configured on the development system (preferred) or the command is run as root with ‘sudo’ (not encouraged). See:

• https://openocd.org/doc/html/Running.html

• https://forgge.github.io/theCore/guides/running-openocd-without-sudo.html

• Start GDB with:

  $ arm-nuttx-eabi-gdb -tui nuttx
  

• In GDB:

  (gdb) target remote localhost:3333
  (gdb) monitor reset halt
  (gdb) load
  

Hardware

MCU Clocking

By default, the MCU on this board is clocked from the MCU’s internal HSI clock, and only this option is supported by software at this time.

If software support is added for it, the MCU could be clocked from the following other sources: a 24 MHz oscillator on X2, MCO from STLINK-V3E, or external clock from connector CN9, pin 26.

GPIOs

Buttons

The board has 5 user buttons in the form of a 4-direction “joystick” with a selection button (pressing down on the “joystick”).

LEDs

The board has 4 user LEDs.

RGB Power LED

The board has a super bright RGB power LED.

Caution: For eye safety, ensure that the power LED is covered by the diffuser that comes installed over it.

Serial Consoles

The MCU’s USART3 is connected to the on-board STLINK-V3E and exposed to the PC as a Virtual COM Port over the same Micro-USB Type B connection used for programming/debugging.

On Debian Linux, this shows up as /dev/ttyACM0. Other operating systems may differ.

FLASH Bootloader Support

If implementing a FLASH bootloader, turn on Kconfig option CONFIG_STM32_DFU. This option activates an alternate linker script, scripts/ld.script.dfu, which causes NuttX to leave a gap at the start of FLASH, leaving that space for the FLASH bootloader. See scripts/ld.script.dfu for details. It also causes NuttX to relocate its vector table and possibly make other adjustments.

One possible bootloader is STmicro’s OpenBootloader “middleware” supplied with STM32CubeG4 version 1.3.0. On the host (PC), it should be possible to use STmicro’s STM32CubeProgrammer or the stm32loader.py script from https://github.com/jsnyder/stm32loader. That script can be invoked with parameters such as:

stm32loader.py -p /dev/ttyACM0 -a 0x08006000 -e -w -v -g 0x08006000 nuttx.bin

where the given address (0x08006000 in this case) must match the starting address in scripts/ld.script.dfu.