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+# 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
+
+## RGB LED
+
+- `PA0` = GND, drive low
+- `PA1` = red
+- `PA2` = green
+- `PA3` = blue
+- The RGB examples use these pins as a visible status output
+
+## 5-Way Button Board
+
+- `PB12` = GND, drive low
+- `PA10` = VCC, drive high
+- `PB13` = right
+- `PB14` = down
+- `PB15` = left
+- `PA8` = center
+- `PA9` = up
+- Assumption: the button inputs read high when pressed
+- The workshop uses `PA8` as the default center button in the simplest examples
+- TODO: flip the input polarity if your module is active-low instead
+
+## Probe Wiring
+
+- `SWDIO` -> `SWDIO`
+- `SWCLK` -> `SWCLK`
+- `GND` -> `GND`
+- `3V3` -> `3V3` reference