Blue Pill USB HID game controller connection guide

• USB power input
  • USB host VBUS
  • VBUS (H4-1)
• USB return
  • USB host ground
  • GND (H4-5)
• Board logic rail
  • 3V3 (H3-1)
  • 3.3 V measurement point

Bench checks

• Identify the USB power input and ground in the board schematic.
• Measure roughly 3.3 V between the board logic rail and ground. Check for a short or wrong connector if the rail is low.

STM32F103C8T6 Blue Pill connector map

Connect and test one button

• Logic supply
  • 3V3 (H3-1)
  • R1.1
• Button sense
  • A0 (H1-5)
  • R1.2
  • Switch terminal 1
• Return
  • G (H2-2)
  • Switch terminal 2

Bench checks

• Confirm that the host enumerates a joystick. If it does not, verify USB clock, cable and D+ pull-up first.
• Check that the host shows button press and release once for each switch cycle. Add debounce in firmware if needed.

USBComposite_stm32f1 joystick example and Blue Pill board schematic.

Highlighted contacts are used in the required step or selected circuit. Select a contact to inspect it.

The companion shows a one-button bench circuit with the joystick class. The button GPIO and resistor are choices for this example.

STM32F103C8T6 Blue Pill

The documented blue PCB has two 20-contact headers, SWD and Micro USB. Its PC13 user LED is active low. The USB D+ pull-up varies across production boards.

• Original Spark Logic project discussion· Author’s hardware, firmware and bench notes.
• STMicroelectronics RM0008 reference manual· Timer modes, DMA request mapping and USB registers.
• USBComposite_stm32f1 source· HID joystick class, descriptors and examples.
• STM32-base · STM32F103C8T6 Blue Pill· Board identification, connector numbering and documented net destinations.
• STMicroelectronics MCU datasheet· MCU electrical specifications and package pin functions.
• STM32F103C8T6 Blue Pill schematic· PCB power, debug, connector and peripheral wiring.