Hi~I use STM32F103C8T6 to print string. The code was generated by CubeMX and I congfiged the USART1. And it can not to transmit any char. But USART2 and USART3 are OK! Why?

[waclawek.jan]

Hardware is OK? Which pin are you using as USART1_Tx? How is it connected? Did you observe it using oscilloscope/logic analyzer?

Read out and check/post content of relevant USART/GPIO/AFIO registers.

JW

[Tesla DeLorean · Accepted solution]

PA9/PA10 GPIO pins and clock initialization look Ok

Some board level details might help here.

Send 0x55 pattern continuously, scope that.