SWD program/debug on custom board

[NDicostanzo]

Hello everyone

I'll receive soon a custom board based on an STM32 microcontroller (still not sure about the specific part number) and I'll have to flash FW updates on it. A few questions about it:

1) There's a 4 pin header connector on the board (VCC, SWCLK, GND, SWO) and I have two STLink programmers (STLink V2 and V2/ISOL). Is this connection scheme correct? (Left header connector, right STLink 20 pin connector).

VCC -> 1

SWCLK -> 9

GND -> 3

SWO -> 13

2) Will this work fine even if I have no SWDIO pin on the header connector? 

Thank you very much in advanced

Nick

[Andrew Neil · Accepted solution]

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@NDicostanzo wrote:

2) Will this work fine even if I have no SWDIO pin on the header connector?

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No: you need SWDIO for programming!

It would also be wise to provide NRST on the programming connector - this can get you out of some "stuck" situations.

https://wiki.segger.com/SWO

https://wiki.segger.com/Target_Interface_SWD 

https://developer.arm.com/documentation/101636/0100/Debug-and-Trace/JTAG-SWD-Interface 

https://community.st.com/t5/stm32-mcus-products/stm32-mcu-choosing-and-programming/m-p/657314/highlight/true#M239894

#SWD #SWDConnector

[NDicostanzo]

Thank you very much. This confirms my initial concerns.