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FJB2069
Senior
Dec 3, 2020 5:28 PM UTC
Solved

Do I need jtag and swd interfaces?

I will be using STM32F4 CPU in custom boards. The PCB will be space constrained and I plan on using STMX&IDE for development debug/programming devices. So is there a need for JTAG interface (10 pin) or can I get away with just having the SWD header?

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TDK
TDKBest answer
Dec 3, 2020 5:56 PM UTC

You don't need both. SWD only is okay.

(Technically you don't need either, but it makes debugging hard/impossible.)

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3 replies

TDK
TDKBest answer
Dec 3, 2020 5:56 PM UTC

You don't need both. SWD only is okay.

(Technically you don't need either, but it makes debugging hard/impossible.)

"If you feel a post has answered your question, please click ""Accept as Solution""."
FJB2069
FJB2069Author
Senior
Dec 3, 2020 5:59 PM UTC

Thanks!

eleventen
Associate III
Dec 4, 2020 1:31 AM UTC

FWIW, you only really need three pins for debug, SWDIO, SWCLK, and GND. It is important to make sure there is a ground wire between the SWD pins. In one design, we found that a ribbon cable with SWDIO and SWCLK immediately next to each other was vulnerable to cross-talk and the interface would not operate reliably.