1.) Create a new CubeMx project for your micro controller
2.) In System Core -> RCC -> High Speed Clock (HSE) select Crystal/Ceramic Resonator
3.) In System Core -> SYS -> Timebase Source select TIM1
4.) In Middleware -> FREERTOS -> Interface select CMSIS_V2
4.1.) In Middleware -> FREERTOS -> Configuration -> Task and Queues double click the defaultTask and set a stack size of 3000. It has to be greater than 10.000 byte (3000 words * 4 byte = 12.000 byte).
5.) In Connectivity choose the UART / USART that you want to use.
5.1.) In the Uart configuration, go to DMA Settings. Click on the Add button. Click on the Select dropdown and choose both Rx and Tx.
5.2.) Click on the Rx DMA you've just created and for Mode choose Circular.
5.3.) For the priority of the DMA choose Very high for both Rx and Tx.
5.4.) Go to NVIC Settings of the UART and activate the UARTx global interrupt.
6.) Set up the Clock Configuration for your micro controller
7.) In Project Manager select a folder where to generate your code
7.1.) In Toolchain / IDE select Makefile
7.2.) Optional: In Project Manager -> Code Generator select Generate peripheral intitialization as a pair of '.c/.h' files per peripheral
8.) Click on Generate Code
9.) In the root folder of the code you've just generated, clone the following repository (into a subfolder, don't change its name).:

https://github.com/micro-ROS/micro_ros_stm32cubemx_utils.git