This one covers the same territory as my Make Your Own MCU Boards talk, but live and on camera: how little you actually need to bring up a microcontroller. The chip in question is an STM32C071KBT3 — a 32-pin QFP part — paired with a breakout board from Adafruit. Solder the chip down, add header pins, and you’re most of the way to a working circuit.

What’s left is the same list of five things every MCU needs, no matter the vendor:

  1. Power — digital supply pins tied to the rails, with decoupling capacitors as a nice-to-have rather than a requirement. Separate analog power pins can share the digital rail too, at the cost of a noisier ADC.
  2. Reset — the STM32C0 has an internal pull-up on NRST, so the pin needs nothing extra. A two-pin breadboard-mount button gives you a manual reset if you want one.
  3. Clocking — the internal RC oscillator is enough for most projects. An external clock only earns its keep when you need precision timing, like USB or a real-time clock, and a packaged oscillator (rather than a hand-tuned crystal circuit) is the more reliable way to add one.
  4. Programming — an ST-Link V2 debug adapter supplies SWDIO, SWCLK, and reset directly; no extra circuitry needed.
  5. Specialty pins — BOOT0 controls where the STM32C0 starts executing after reset, and it’s disabled by default, so it’s another pin you can leave alone.

Add power, wire up SWD, and drop in a quick CubeMX Blinky project, and that’s a working STM32 for only a few dollars in new parts — cheaper if you use a less expensive STM32C0 variant and make your own breakout boards.

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