#774 STM32U385RG Dev Board
About the STM32U385RG development board, installing STM32CubeIDE on macOS, and making a simple LED blinky demo from scratch.
Notes
About the NUCLEO-U385RG-Q
The NUCLEO-U385RG-Q evaluation board is an STM32 Nucleo-64 development board with STM32U385RG, supports Arduino and ST morpho connectivity.
Features
- STM32 microcontroller in an LQFP 64‑pin package
- Internal SMPS to generate Vcore logic supply, identified by ‘-Q’ suffixed boards
- USB Type-C® sink device FS
- One user LED shared with ARDUINO® Uno V3
- RESET and USER push-buttons
- 32.768 kHz crystal oscillator
- Board connectors:
- USB Type-C®
- ARDUINO® Uno V3
- ST morpho extension pin headers for full access to all STM32 I/Os
- Flexible power-supply options: ST-LINK USB VBUS, user USB connector, or external sources
- On-board STLINK-V3EC debugger/programmer with USB re-enumeration capability: mass storage, Virtual COM port, and debug port
- Comprehensive free software libraries and examples available with the STM32Cube MCU Package
- Support of a wide choice of Integrated Development Environments (IDEs) including IAR Embedded Workbench®, MDK-ARM, and STM32CubeIDE
Board Features and Configuration
STM32 NUCLEO Features
ST-LINK Status LED
- The LED is blinking red: the first USB enumeration with the PC is taking place. If an STLinkUpgrade application is running, the firmware is being programmed.
- The LED is red: the ST-LINK is in the idle state (the USB enumeration with the PC is finished and the ST-LINK is waiting for an application to connect).
- The LED is blinking green and red alternately: data is being exchanged between the target and the PC.
- The LED is green: the last communication with the target has been successful.
- The LED is orange: the last communication with the target has failed.
- The LED is blinking red then orange: USB port detection failure. Check the USB connectors and cable.
Building a “blinky” Demo
To exercise the board, I’ll create a program to flash the onboard LED, using the STM32CubeIDE on macOS.
Installing STM32CubeIDE
STM32CubeIDE is an all-in-one multi-OS development tool, which is part of the STM32Cube software ecosystem.
The ID is available for free down download here.
More information about the IDE:
Installing on macOS:
Welcome screen:
- to enable updates and examples etc, sign into myST from “Help > STM32Cube Updates > connection to myST”
Create new STM32 Project
Start new STM32 project in the blinky folder.
Adding STM32U3xx_Nucleo BSP Driver
To add specific board support for STM32U3xx_Nucleo, need to add the driver. I was a little surprised this is not handled through the IDE, but it seems we just need to copy the correct BSP files into our project.
The STM32U3xx_Nucleo BSP Driver fiels can be obtained from either:
- STM32Cube MCU Package for STM32U3 series download
- or from the GitHub source https://github.com/STMicroelectronics/stm32u3xx-nucleo-bsp
I copyied and including the files as follows:
- copied STM32U3xx_Nucleo drivers to blinky/Drivers/BSP/STM32U3xx_Nucleo/
- “File > Refresh” the project to have the new files appear in the IDE
- Right-click the
blinky/Drivers/BSP/STM32U3xx_Nucleo/driver folder and choose “Add/remove include path” add to debug and release - copy
stm32u3xx_nucleo_conf_template.hfrom the BSP folder to the project includes asstm32u3xx_nucleo_conf.h. It did not need any modification - defaults work OK
Customizing the main function
A simple blinky in main.c (with boilerplate comments removed):
int main(void)
{
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* Configure the system clock */
SystemClock_Config();
/* Initialize all configured peripherals */
MX_ICACHE_Init();
/* -1- Enable GPIO Clock (to be able to program the configuration registers) */
LED2_GPIO_CLK_ENABLE();
/* -2- Configure IO in output push-pull mode to drive external LEDs */
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
GPIO_InitStruct.Pin = LED2_PIN;
HAL_GPIO_Init(LED2_GPIO_PORT, &GPIO_InitStruct);
while (1)
{
/* Toggle LED2 with delay */
HAL_GPIO_TogglePin(LED2_GPIO_PORT, LED2_PIN);
HAL_Delay(500);
}
}
Programming
With the board connected with USB-C cable, build and run the project
Transcript from the console:
STMicroelectronics ST-LINK GDB server. Version 7.10.0
Copyright (c) 2025, STMicroelectronics. All rights reserved.
Starting server with the following options:
Persistent Mode : Disabled
Logging Level : 1
Listen Port Number : 61234
Status Refresh Delay : 15s
Verbose Mode : Disabled
SWD Debug : Enabled
InitWhile : Enabled
Waiting for debugger connection...
Debugger connected
Waiting for debugger connection...
Debugger connected
Waiting for debugger connection...
-------------------------------------------------------------------
STM32CubeProgrammer v2.19.0
-------------------------------------------------------------------
Log output file: /tmp/STM32CubeProgrammer_5XnD4q.log
ST-LINK SN : 0027002F3333511731363730
ST-LINK FW : V3J16M7
Board : NUCLEO-U385RG-Q
Voltage : 3.29V
SWD freq : 8000 KHz
Connect mode: Under Reset
Reset mode : Hardware reset
Device ID : 0x454
Revision ID : Rev Z
Device name : STM32U3xx
Flash size : 1 MBytes (default)
Device type : MCU
Device CPU : Cortex-M33
BL Version : 0xE2
Debug in Low Power mode enabled
-------------------------------------------------------------------
Choose flashing speed for Cortex M33 series.(default speed=Reliable)
-------------------------------------------------------------------
Opening and parsing file: ST-LINK_GDB_server_myMFdf.srec
Memory Programming ...
File : ST-LINK_GDB_server_myMFdf.srec
Size : 6.11 KB
Address : 0x08000000
Erasing memory corresponding to sector 0:
Erasing internal memory sectors [0 1]
Download in Progress:
File download complete
Time elapsed during download operation: 00:00:00.256
Verifying ...
Download verified successfully
Shutting down...
Exit.
And now I have a blinking LED!