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USB CDC - Maximum Baud Rate of device side (not host)

AA.10
Associate III

I am working on STM32L496 nucleo board.

I would like to transfer data from STM32L496 (as device) to host PC (RX is not required).

currently, the baud rate is ~200kbyte. no matter if I am increasing the packet size

(CDC_DATA_FS_MAX_PACKET_SIZE) to 512 byte or more.

the main loop is trying to send data all the time without any derlay

(where TX buffer size is 1536)

first, what is the maximum baud rate from the device side (not host)? or the maximum possible baud rate is the same for both host and device sides?

second, for maximum baud rate what should be the right configuration?

1 REPLY 1
Bob S
Principal

Between the STM32 and the PC, across the USB, baud rate has no meaning and no influence over the data transfer rate. The data will be sent as fast as the STM32 can buffer and send it, and as fast as the PC can read it. Limited of course by the max USB bit rate, USB packet and CDC protocol overhead. Baud rate only matters if the STM32 is going to send/receive data over a physical UART to the outside world.