This repository contains the firmware for FreeJoy, a highly configurable USB game controller (joystick, HOTAS, steering wheel) based on the STM32F103 (Blue Pill). The firmware implements a composite USB device with joystick HID, custom HID (for configuration), and CDC (for SimHub telemetry). It supports a wide variety of input sensors (ADC, magnetic encoders via SPI/I2C), buttons (GPIO, shift registers), encoders, LEDs (matrix and addressable RGB), and PWM outputs. Configuration is stored in flash and managed via a companion PC tool. A separate USB HID bootloader enables firmware updates. The code is bare-metal, leveraging the deprecated STM32 Standard Peripheral Library and CMSIS 3.5.0, with SEGGER RTT/SysView for debugging. The architecture is monolithic but modular within the firmware, with clear separation between bootloader and application.