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NUCLEO-L152RE - Sending data at 115200 baud on USART2 kills ST-LINK VCP

Question asked by simmons.sean on May 17, 2014
Latest reply on May 20, 2014 by Clive One
I trying to send continuous serial data at 115200 baud using USART2 which is connected to the ST-LINK portion of the NUCLEO board.  ST-LINK implements a VCP which I'm accessing via a terminal on my PC.  If I space the characters out (e.g. send 1 every 100 ms) everything works as expected - terminal on PC is updated with the characters as they are received.  If I send batches of characters (e.g. send 5 every 100ms), again everything works as expected.  However, if I send continuous characters then the VCP stops working (I receive nothing on the terminal), even though I can see the data being sent on the RX pin of CN3 on the NUCLEO board using an oscilloscope.   Additionally the ST-LINK commands from the PC no longer work (I can't debug or load code), nor does the USB drive emulation work.  It seems that U2 (STM32F103CBT6) that implements the ST-LINK, USB Drive and VCP "crashes" when receiving continuous data at 115200 baud on PA3/STLINK_TX.

Has anyone else experience this?
Is this a known limitation, and if so what is the maximum continuous character rate that the ST-LINK VCP can handle?
Are there any known work arounds?
Would it be possible to get updated ST-LINK firmware for the NUCLEO board that addresses this issue?

As a side note, once code has been loaded that sends continuously at 115200 baud you can no longer load code on to the NUCLEO board unless you remove SB13, then load code, then reinstall SB13.

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