Usart oversampling on the STM32F10X product line

[michiel]

Posted on November 28, 2011 at 11:38

Hi STM32 experts,

I'm a little confused. Does or doesn't the STM32F10X product line support 8 bit oversampling? The reference manual does not mention the OVER8 bit, suggesting usarts in this productline always uses 16 bit oversampling(OVER8 = 0). However looking into the usart peripheral library source code, 8 bit sampling (OVER8 = 1) does seem to be supported. More strangely when debugging my STM3210C-EVAL board running the peripheral library usart code it jumps into the OVER8==0 parts of the USART_Init function but results in an USART2 clock being twice to high. This suggests USART2 on the STM32F107VCT does 8bit oversampling hence the twice to high bitrate. I checked the PCLK1 frequency to be 36MHz (and HCLK 72Mhz)

regards,

          Michiel

[Tesla DeLorean]

Posted on November 28, 2011 at 15:24

The F10x series are not documented to support the OVER8 mode, it is not provided for in the older libraries, the newer versions do have code as part of a more unified library for the STM32 series in general.