USART3，USART4 how to use

[Khe.11]

Dear

I use the STM32H7B3I-DK this board,and I read the manual.The instruction says I can use

CN11 digital pin name D0 and D1,but D1 is (USART4_TX)​,D0 is (USART3_RX).Then how do I use the USART3, because do not find USART3_TX​

[Tesla DeLorean]

Surely you'd just configure board, setting one for TX only, the other for RX only, and then send data out via one, and receive from the other.

A tad more complicated, but manageable

[Khe.11]

Sorry,I do not understand what you mean.So D0 and D1 are both USART3 or USART4?​

[Ons KOOLI]

Hi Khe.1,

After checking the user manual, I found that USART4_TX is connected to D1 and USART4_RX is connected to D0.

Unfortunately, with the STM32H7B3I-DK, and according to its reference manual, you can only use USART1, USART2, USART4, or USART6 for transmission and reception via USART. 

 Nevertheless, according to the RM0455, USART3 can be used with one of the following pins : PB10/PB11/PD8/PD9 (see page 137). But according to the schematic of the board PB10 & PB11 are used by the ULPI. PD8 & PD9 are "free" pins, so you can use them by taking in consideration changing the alternate function, because according to the reference manual of the board these pins are by default dedicated to FMC.

I really hope this is helpful.

with Best Regards,

Ons.