Core2Keypad

M5Stack Core2 as a Bluetooth trackpad: the whole screen is the input area, no physical buttons. Swipe up and down to scroll, press and drag to move the pointer; the left drawer switches modes, toggles haptics, and selects which of up to three connected hosts receives the input.

中文说明

Modes

Mode	Swipe up / down	Tap	Hold 500 ms	Hold ~0.3 s, then drag
SLIDE	wheel: swipe down scrolls up, swipe up scrolls down (natural scrolling)	—	—	—
MOUSE	move the pointer	left click	right click	left-button drag (select text, move windows)

One wheel notch per 24 px of travel, at most 12 per swipe, sent while you move; the on-screen hint stays for 3 s after you stop. Pointer sensitivity: 1 screen pixel ≈ 1.2 mouse counts.

Dragging and moving are told apart by a short pause: press and move straight away and the pointer just moves; hold for about 0.3 s before moving and the left button is held down until you lift.

Toolbar

Swipe in from the left edge (x < 16, at least 60 px) to pull out the drawer:

• VIBRATION — haptics on/off, lit when on
• MODE — SLIDE / MOUSE, the colour follows the mode (blue = slide, amber = mouse)
• DEVICE — current host slot D1/D2/D3, lit when that slot is online; tap to cycle

Each tile is 64×106 and fully tappable; tap a tile to toggle, tap outside the drawer to close. Everything is stored in NVS and survives a reboot. With haptics on, a scroll, left click or right click gives a 40 ms buzz, and a small vibration icon sits to the left of the battery.

Multiple hosts (3 slots)

The ESP32 BLE controller supports three simultaneous connections (CONFIG_BTDM_CTRL_BLE_MAX_CONN=3), so there are exactly three slots:

• slots are keyed by Bluetooth address in NVS, so the mapping and the selection survive reboots and deep sleep
• DEVICE shows the current slot; tapping cycles D1 → D2 → D3 → D1
• only the selected slot receives reports; the other connections stay up — switching never disconnects
• the status bar always shows ● D<n>: green = that slot is online, amber = that slot is offline but another host is online, grey = nothing is connected
• an empty or offline slot silently drops reports and never jumps to another device on its own
• a second or third host takes a free slot; when all three are taken, the least recently used offline slot is evicted

Screenshots

Slide mode (idle)	Drawer: VIBRATION / MODE / DEVICE

Swiping (wheel hint, hides after 3 s)	Mouse mode

Screen

The status bar holds the title, the mode chip (blue SLIDE / amber MOUSE), the current host slot ● D1 and the battery; a small vibration icon appears when haptics are on.

• the bottom of the panel hints at the gestures; a swipe replaces it with direction, notch count and a progress bar for 3 s
• after 3 s idle the backlight fades to 20 %, and any touch brings it back immediately
• after 5 min idle the screen turns off and the CPU drops to 80 MHz; 5 min later the board enters deep sleep, and a touch wakes it
• a short press of the side power button enters deep sleep right away; a long press is still the AXP hardware power-off

Serial console (921600)

Command	What it does
C2_INFO	version, mode, haptics, connection count, slot, drawer state, boot count, uptime
C2_BLE	BLE server, HID service handle, connection state
C2_CCCD	subscription bits of the two input reports (0100 = subscribed)
C2_MODE <0|1>	0 = SLIDE, 1 = MOUSE
C2_VIB <0|1>	haptics on/off
C2_BUZZ	buzz once; ok=1 means the motor is wired up
C2_DISC	drop the link of the current slot (for reconnect tests)
C2_HOSTS	list live connections: conn / slot / address / active
C2_HOST <1|2|3>	select a slot directly
C2_T <0|1> <x> <y>	inject a touch; C2_T 9 hands control back to the panel
C2_SCREEN	full-screen RGB888 capture (tools/c2_screenshot.py saves it)
C2_SLEEP	enter the first sleep stage now
C2_DEEPSLEEP	enter deep sleep now

End-to-end check

pwsh tools/c2_e2e.ps1

Hooks the Windows mouse API, injects touches through C2_T and asserts wheel, clicks, movement, drawer switching, slot cycling and host routing — 17 checks.

Verified

Check	Result
SLIDE · swipe up 140 px → scrolls down	5 × WHEEL -120
SLIDE · swipe down 140 px → scrolls up	5 × WHEEL +120
MOUSE · tap	LBUTTON_DOWN / LBUTTON_UP
MOUSE · hold 700 ms	RBUTTON_DOWN / RBUTTON_UP at 500 ms
MOUSE · drag	continuous MOVE events
MOUSE · hold then drag	LBUTTON_DOWN + MOVE ×2 + LBUTTON_UP
Left-edge swipe	drawer opens, no mouse events leak
Drawer	VIBRATION toggles, MODE switches, DEVICE cycles D1 → D2 → D3
Tap outside the drawer	closes
Haptics motor	C2_BUZZ ok=1
Persistence	mode, haptics and slots survive a reboot
Link recovery	host reconnects within 2 s after C2_DISC
Scroll hint	hides 3 s after the last notch
Sleep / wake	asleep=1 after C2_SLEEP, back to 0 on touch
Deep sleep	serial goes silent, RTS reset recovers the board
Multi-host · switch to an empty slot	host receives 0 button events
Multi-host · switch back	LBUTTON_DOWN resumes

Known limitations

• no encrypted pairing (Just Works), so anyone nearby can connect and type
• at most 3 hosts online at once; a fourth connection is refused by the controller
• slots are identified by number only — a BLE peripheral cannot read the host's name
• whether the wheel scrolls a given app depends on that app handling generic scroll events
• haptics are on/off only (AXP192 LDO3 gives a fixed 1800 mV), no strength levels
• two-finger gestures are not supported: the panel reports a single touch point
• waking from deep sleep is a cold boot — about 1.5 s until the screen is up and 5 s until Bluetooth is back