🕹️ STM32F411 USB Game Controller

A fully custom USB game controller built using the STM32F411CEU6 microcontroller. Features 9 buttons, 2 analog joysticks, DMA ADC sampling, and a modified Xbox 360 HID descriptor.

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📸 Final Product

⚠️ Note: The current hardware setup is not on a proper PCB or veroboard, as this was developed under a tight university schedule with limited time. While the circuit might not look polished, it works reliably for demonstration and testing purposes. A proper PCB or veroboard design is planned and will be uploaded soon. Stay tuned!

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📦 Clone and Build Instructions

# Clone the repository
git clone https://github.com/yourusername/stm32-usb-gamepad.git
cd stm32-usb-gamepad

# Open in STM32CubeIDE or import as existing project
# Flash to your STM32F411 using ST-Link or DFU

Full documentation continues below...

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STM32F411CEU6 USB Game Controller

A custom USB game controller built using the STM32F411CEU6 (Black Pill) microcontroller. This controller features 9 buttons, 2 analog joysticks, and communicates with a PC via USB HID using a modified Xbox 360-style HID report descriptor. It also uses ADC in circular DMA mode, deadzone processing, and timer-triggered sampling.

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🔧 Features

• ✅ 9 Buttons (including Option button)
• ✅ 2 Analog Joysticks (X/Y and Rx/Ry)
• ✅ USB HID Gamepad Interface
• ✅ DMA + Timer-based ADC Sampling
• ✅ Active-low Button Handling
• ✅ LED Indicators for joystick movement
• ❌ Bluetooth HID (planned but not implemented)

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📂 Project Structure

STM32_Gamepad_Project/
├── Core/
│   ├── Inc/
│   │   └── main.h
│   ├── Src/
│   │   ├── main.c
│   │   ├── usb_device.c
│   │   └── usbd_custom_hid_if.c
├── USB_DEVICE/
│   └── usbd_customhid.c/h
├── Drivers/
│   └── STM32F4xx_HAL_Driver/
└── README.md <-- (this file)

🕹️ Button Mapping

Button	GPIO Pin	HID Bit	Description
X	PB4	0	Action Button
Y	PB5	1	Action Button
A	PB2	2	Action Button
B	PB3	3	Action Button
D-Pad Up	PB6	12	Directional
D-Pad Down	PB7	13	Directional
D-Pad Left	PB8	14	Directional
D-Pad Right	PB9	15	Directional
Option Button	PA0	9	Start/Menu button

• All buttons are active-low and polled via GPIO.

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🎮 Joystick Mapping

Left Joystick (Joystick 1)

• VRx: PB1 → adcValues[1]
• VRy: PB0 → adcValues[0]

Right Joystick (Joystick 2)

• VRx: PA6 → adcValues[2]
• VRy: PA7 → adcValues[3]

LED Indicators

• PC13 toggles when any button is pressed.
• PC10 and PA10 toggle depending on joystick movement.

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📏 ADC Details

• Resolution: 12-bit (0–4095)
• Reference Voltage: 3.3V
• Mode: Circular DMA
• Trigger: TIM3 Timer

🧮 Joystick Processing

#define DEAD_ZONE 200

uint16_t apply_deadzone(uint16_t raw) {
    if (raw > 2048 - DEAD_ZONE && raw < 2048 + DEAD_ZONE)
        return 2048;
    return raw;
}

uint8_t adc_to_hid_u8(uint16_t raw) {
    int32_t val = raw - 2048;
    val = (val * 127) / 2048;
    if (val > 127) val = 127;
    if (val < -128) val = -128;
    return (uint8_t)(val + 128); // Shift to 0–255 range
}

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📤 HID Report Descriptor (Xbox360 Style)

0x05, 0x01,        // Usage Page (Generic Desktop)
0x09, 0x05,        // Usage (Gamepad)
0xA1, 0x01,        // Collection (Application)
  0x05, 0x09,      // Usage Page (Button)
  0x19, 0x01,      // Usage Minimum (Button 1)
  0x29, 0x10,      // Usage Maximum (Button 16)
  0x15, 0x00,      // Logical Minimum (0)
  0x25, 0x01,      // Logical Maximum (1)
  0x75, 0x01,      // Report Size (1)
  0x95, 0x10,      // Report Count (16)
  0x81, 0x02,      // Input (Data, Variable, Absolute)

  0x05, 0x01,      // Usage Page (Generic Desktop)
  0x09, 0x30,      // Usage (X)
  0x09, 0x31,      // Usage (Y)
  0x09, 0x33,      // Usage (Rx)
  0x09, 0x34,      // Usage (Ry)
  0x15, 0x00,
  0x26, 0xFF, 0x00, // Logical Maximum (255)
  0x75, 0x08,      // Report Size (8)
  0x95, 0x04,      // Report Count (4)
  0x81, 0x02,      // Input (Data, Variable, Absolute)

  0x09, 0x32,      // Usage (Z)
  0x09, 0x35,      // Usage (Rz)
  0x75, 0x08,
  0x95, 0x02,
  0x81, 0x02,
0xC0               // End Collection

🧾 Report Structure (8 bytes)

Byte Index	Description
0	Buttons LSB
1	Buttons MSB
2	X (Joystick 1)
3	Y (Joystick 1)
4	Rx (Joystick 2)
5	Ry (Joystick 2)
6	Z (Trigger 1)
7	Rz (Trigger 2)

🧠 Initialization Summary

• Clock: HSE on PH0/PH1

• ADC1: Circular DMA, 4 channels

• GPIO: All buttons input (pull-up), LEDs as output

• Timer 3: Triggers ADC sampling

• USB: Configured as FS Device on PA11/PA12

📚 Dependencies

• STM32 HAL Drivers

• STM32CubeMX-generated initialization

• Custom HID Descriptor override

❗ Known Issues / Notes

Bluetooth via ESP32 was planned but not implemented

Center calibration happens after 200ms delay on boot

Some GPIOs (e.g., SWD pins) are repurposed — debugging over UART might conflict

📸 Future Improvements

Add Bluetooth HID support via ESP32 UART

Implement debouncing or EXTI for buttons

Add OLED status screen or RGB LEDs

🧑‍💻 Author

@Hassan-Mef – Custom Game Controller using STM32F411 Black Pill

Feel free to fork and modify!