Magic Stick

A palm-sized Bluetooth mouse, microphone, motion display, and shortcut trigger built on M5StickC-Plus.

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Magic Stick is firmware for an M5StickC-Plus + JoyC HAT that turns a tiny handheld device into a Bluetooth input companion:

Competition project page: Magic Stick on Hackster.io

• JoyC controls the computer mouse.
• JoyC click sends left click.
• JoyC double-press-and-hold enters scroll mode.
• Internal PDM mic becomes a Classic Bluetooth HFP microphone.
• IMU drives a live 3D cube on the screen.
• BtnA double-click toggles function mode and sends one macOS F15 tap.

The product exposes a single Classic Bluetooth device name:

Magic Stick

Product Snapshot

Area	What It Does
Input	Bluetooth HID mouse movement, left click, vertical wheel, horizontal pan
Audio	Bluetooth HFP microphone using the StickC internal PDM mic
Motion	IMU-based 3D cube rendered on the 135x240 screen
UI	Two-page Retro Scope interface: Status and Magic
Shortcut	BtnA double-click sends macOS F15 after mode switching
Hardware safety	JoyC and mic are never active on PortA at the same time

Demo Video

Watch the Magic Stick demo on YouTube

Gallery

Hardware

Part	Role
M5StickC-Plus	ESP32-PICO-D4, LCD, IMU, buttons, battery, PDM mic
M5Stack JoyC HAT	I2C joystick and click input, address 0x54
PortA GPIO0/GPIO26	Shared bus/pin resource switched between JoyC and mic usage

Interaction Model

Magic Stick keeps the UI deliberately small: one maintenance page and one work page.

Page	Purpose
Status	Bluetooth state, HFP audio channel, battery, pairing state
Magic	Joystick, IMU cube, mic icon, mic spectrum, battery cells

Buttons

Action	Page	Result
BtnB short press	Status	Enter Magic
BtnB short press	Magic	Return to Status
BtnA single click	Magic	Wait 450ms, then toggle Mic/Joystick
BtnA double click	Magic	Toggle Mic/Joystick, then send one F15 HID tap
BtnB hold 3s	Any	Re-enter discoverable/pairing state
BtnB hold 8s	Any	Clear Bluetooth bonds and restart

Magic Function States

When joystick is on:

• JoyC X/Y controls mouse movement.
• JoyC press sends left click.
• One click followed by a second hold within 450ms enters scroll mode.
• Scroll mode sends wheel/pan instead of mouse movement.

When mic is on:

• JoyC I2C is shut down and PortA is released.
• Internal PDM mic starts.
• HFP audio path sends real PCM to the host.
• HID remains connected, but mouse movement is not sent.

Bluetooth Stack

flowchart TD
    A["Magic Stick"] --> B["Classic BT"]
    B --> C["HID Device"]
    B --> D["HFP HF Client"]
    C --> E["Mouse report: buttons, dx, dy, wheel, pan"]
    C --> F["Keyboard report: F15 down/release"]
    D --> G["Mic uplink PCM"]

Loading

The firmware uses one Classic Bluetooth identity and one product name. After a HID descriptor change, macOS may cache the old descriptor; remove and re-pair Magic Stick if keyboard shortcut reports do not appear.

UI: Retro Scope

The UI uses a black background, warm white linework, compact geometry, and color only where it communicates state.

Element	Behavior
Joystick dot	Red when joystick is active, gray when disabled, yellow in scroll mode
Joystick press	Dot grows while pressed
Mic icon	Green when mic is active, gray when muted/off
Spectrum	Shows live mic energy bins
Battery	12 compact cells; green above 60%, yellow from 20%-59%, black below 20%

Firmware Layout

main/
  bluetooth/      Classic BT HID mouse, F15 key report, HFP mic control
  joystick/       JoyC I2C recovery, button decode, mouse/scroll controller
  mic/            PDM mic capture and spectrum data
  ui/             LVGL Status and Magic screens
  device_mode.*   PortA-safe peripheral switching
  button_action.* BtnA single/double-click state machine

Build

. /Users/xurui/esp/esp-idf-v5.4.2/export.sh
idf.py build

Flash

idf.py -p /dev/cu.usbserial-49523D2FE2 -b 115200 flash

If the device remains in download mode after flashing, unplug USB once and power-cycle it.

Host Tests

cc -I main -I main/joystick test/test_button_action.c main/button_action.c -o /tmp/test_button_action
/tmp/test_button_action

cc -I main/joystick test/test_mouse_controller.c main/joystick/mouse_controller.c -lm -o /tmp/test_mouse_controller
/tmp/test_mouse_controller

cc -I main/mic test/test_mic_spectrum.c main/mic/mic_spectrum.c -lm -o /tmp/test_mic_spectrum
/tmp/test_mic_spectrum

cc -I main/bluetooth test/test_bt_pairing_status.c main/bluetooth/bt_pairing_status.c -o /tmp/test_bt_pairing_status
/tmp/test_bt_pairing_status

Current Notes

• ESP-IDF target is esp32.
• M5Unified is pinned through the project dependency lock.
• Magic Stick currently targets macOS-style host workflows, with Windows compatibility expected for the mouse/HFP portions.
• F15 requires an active HID connection. On the Status page, confirm Mouse: OK before testing the shortcut.

License

See LICENSE.