Custom STM32 Board Bring-Up Procedure

Bringing up a custom STM32 board for the first time is nerve-wracking. Here's my systematic procedure that has worked on every board.

Step 1: power-off inspection. Check all polarized components (caps, diodes, ICs) under a loupe. Check for bridges between adjacent pads with a multimeter in continuity mode. Step 2: current-limited power-up. Apply 3.3V through a bench supply in current-limit mode at 100mA. If the current immediately clamps, there's a short. Step 3: check voltage rails with a meter.

Step 4: connect an ST-Link and attempt to connect with STM32CubeProgrammer. A successful connection confirms the MCU is alive, the SWD pins are connected, and the power supplies are working. Step 5: write a minimal blinky firmware and verify the expected GPIO behavior. Only then proceed to peripheral testing.