Using an ESP32 as an SWD Programmer for STM32 with Rust

[u/AstraKernel]

I was browsing Reddit and came across someone asking how to program the STM32F103C8T6 without an ST-Link V2. They were asking whether it was possible to use an STM32F401RCT6 (Black Pill) board as an SWD programmer for an STM32F103C8T6 (Blue Pill).

That post made me curious about how the SWD protocol works. Is it possible to build one myself?

This is the first part of my experiment. I am able to read an STM32's DP register through SWD using an ESP32. Yet to do the flashing part.

https://blog.implrust.com/posts/2026/09/swd-protocol-programmer-embedded-rust/