Even if you do not encounter problems, it will be instructive to use
the Saleae Logic to observe the low-level behavior of the STM32 UART. To
capture data from the lab board it is necessary to connect two wires from
the Saleae Logic to your circuit – ground (gray) and channel 0 (black). The
ground wire should be connected to one of the GND pins and channel 0 to the
USART1 tx (PA9) pin. Connect the Saleae logic analyzer to your computer
and configure the software for Async serial on channel 0.