Electronic – How to daisy chain SWD Debug port

armdebuggingswd

I have multiple mcu's that are configured to communicate with bus topology. I have 10 pins (4 of them is occupied by now)

I need to debug (update firmware online, etc) all of these mcu's. I read this article but I didn't understand how to achieve the goal.

Question: How can I daisy chain these mcu's?

MCU: STM32F407VG

Debug protocol: SWD

Best Answer

How can I daisy chain these mcu's? MCU: STM32F407VG Debug protocol: SWD

These MCUs support JTAG and SWD. While JTAG supports a daisy chain configuration, SWD does not. There is a multi drop extension in SWD 2.0 protocol, but I am pretty sure your MCU does not implement this.

If you really want to debug multiple chips in a daisy chain, use JTAG. Beware: Tool configuration(s) may be non-trivial to do.

Note that you might want to separate a firmware update from your debugging scenario. Firmware updates can be done in multiple ways using a bootloader, so SWD or JTAG is not required in this case.

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