Does the baud rate get shared if I use two or more UARTs?

Forum|Forum|3 years ago
March 10, 2023
2 replies
1637 views

Hi! I am discovering the world of STM32 and currently using a STM32F4 to establish a UART communication (send and receive data). I wrote a pretty basic program to send and receive a message (basically a loop) with a baud rate of 9600. The users manual says that UARTs are running at up to 11.25 Mbit/s. My question is does the baud rate gets shared if I use two UARTs and if so, do they mean 11.25Mbit/s for each UART? Also, I wanted to know how to change the baud rate in STM32CubeMx as whenever I try to it gets back to 115200 (I configured the clock to 84 Mhz and oversampling by 8).

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Best answer by waclawek.jan

> do they mean 11.25Mbit/s for each UART

Yes, UARTs are mutually independent.

Whether at that rate you succeed to push Tx data to them and pull Rx data from them, is another question. And what's the signal integrity at that rate, given some particular interconnection, is yet another. Also, does the device connected to such UART support such baudrate?

The maximum baudrate is dependent on the particular UART's clock, though; and those UARTs which are on the slower APB bus may have a lower limit.

JW

waclawek.janBest answer

Super User

> do they mean 11.25Mbit/s for each UART

Yes, UARTs are mutually independent.

Whether at that rate you succeed to push Tx data to them and pull Rx data from them, is another question. And what's the signal integrity at that rate, given some particular interconnection, is yet another. Also, does the device connected to such UART support such baudrate?

The maximum baudrate is dependent on the particular UART's clock, though; and those UARTs which are on the slower APB bus may have a lower limit.

JW

LimoGrAuthor

Associate II

Thank you very much! That was very clear!

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