IS_USART_BAUDRATE up to 7.5 Mbit/s is wrong for STM32F4xx

[Diez.R.]

Posted on April 21, 2016 at 09:26

Hi all:

On an STM32F407 with the Standard Peripheral Library 1.5.0, I tried to configure USART6 to the documented maximum of 10.5 Mbit/s, and I got an assert in USART_Init(). The problem is here: #define IS_USART_BAUDRATE(BAUDRATE) (((BAUDRATE) > 0) && ((BAUDRATE) < 7500001)) That definition allows a value up to 7.5 Mbit/s. Is that a bug in the library? I just checked, and the Standard Peripheral Library 1.6.1 has the same values in IS_USART_BAUDRATE(). Thanks in advance,   rdiez

[Amel NASRI]

Posted on April 21, 2016 at 16:11

Hi diez.r,

The issue is reported internally to be fixed in coming versions of STM32F4 Standard Peripheral Library.-Mayla-

[Tesla DeLorean]

Posted on April 21, 2016 at 18:43

These rates seem unreasonably high for an asynchronous link, perhaps you can consider better alternatives?

[Diez.R.]

Posted on April 22, 2016 at 13:36

> These rates seem unreasonably high for an asynchronous

> link, perhaps you can consider better alternatives? I wanted a synchronous link (with clock signal). I ran out of SPIs, so I am using USART6 as a replacement, even though I will be losing some performance (for each 8 data bits, the additional start and stop bits are wasted because they do not trigger the clock signal, if I understood the documentation correctly). You call the same function USART_Init() in order to initialise the USART in synchronous mode, right? Regards,   rdiez

[Tesla DeLorean]

Posted on April 22, 2016 at 20:07

That and USART_ClockInit() 

[Tesla DeLorean]

Posted on April 22, 2016 at 20:09

Different family, but might be instructional

STM32F10x_StdPeriph_Lib_V3.5.0\Project\STM32F10x_StdPeriph_Examples\USART\Synchronous\main.c