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Using USB CDC as a passthrough to program another MCU

jeffreyc
Associate

‎2016-02-17 04:43 PM

Posted on February 18, 2016 at 01:43

I'm using an STM32F407 (#1) connected to PC via USB and another STM32F407 (#2) via UART3. I'm trying to program #2 via the bootloader using STMFlashLoader.exe by initializing #1 as a USB CDC device and passing through the signals to #2. 

Is this feasible or am I nuts in the trying to attempt this?
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1 REPLY 1
mark239955_stm1
Associate II

‎2016-02-18 03:21 AM

Posted on February 18, 2016 at 12:21

No, I don't think you're crazy, it can work.

There are a few things to be wary of, including:

  • Follow the advice in the bootloader app note about putting a pullup on the UART receive line.
  • Ensure that the slaved MCU doesn't boot until after the CDC device driver has started.
  • Ensure that your CDC-to-UART bridge has low enough latency and high enough throughput (in both directions) to satisfy the bootloader in the slave and the DFU software on the PC.

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