# Blue Pill Notes

## Baseline

- Board: STM32F103C8T6 Blue Pill
- Core: Cortex-M3
- Default target: `thumbv7m-none-eabi`

## LED

- Most Blue Pill boards wire the onboard LED to `PC13`
- It is usually active-low
- `set_low()` usually turns it on
- `set_high()` usually turns it off

## Button Assumption

- The repo button examples use `PA0`
- Assumed wiring:
  - button between `PA0` and `3V3`
  - firmware enables internal pull-down

## Probe Wiring

- `SWDIO` -> `SWDIO`
- `SWCLK` -> `SWCLK`
- `GND` -> `GND`
- `3V3` -> `3V3` reference