ESP32 BT Trigger

A tiny ESP32 firmware that acts as a Bluetooth trigger for iPhone Shortcuts automations.

The ESP32 presents itself to your iPhone as a Classic Bluetooth device (a mouse). It never sends any input — the act of connecting is the trigger: iOS runs a Shortcuts automation set to "When <device> connects". After a reboot or a dropped link, the ESP32 reconnects on its own to the last paired iPhone.

What you can do with it

Power the ESP32 from something you switch on (a scooter, bike, car, desk lamp, 3D-printer, door…). When it powers up it connects to your iPhone, and your Shortcuts automation fires automatically — for example:

• open a navigation / dashboard app,
• toggle a Focus mode or Do Not Disturb,
• start a timer, set the volume, send a message, run any shortcut.

It's the "when this turns on, do that on my phone" building block, done over plain Bluetooth with no extra app on the phone.

Why a mouse and not a keyboard? While an HID keyboard is connected, iOS hides the on-screen keyboard. A pointing device does not, so your on-screen keyboard keeps working (iOS shows the AssistiveTouch pointer instead).

Why Classic Bluetooth and not BLE? This project is for people who want a Classic-BT HID device recognized by iPhone. (A BLE HID would also work; this one deliberately uses Classic BT via ESP-IDF.) Note: Classic SPP (serial) does not work with iPhone — Classic HID does, which is what this uses.

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Change the name

The Bluetooth name is defined in one place, in src/main.cpp:

#define DEVICE_NAME  "ESP32-BT-Trigger"

Change it, rebuild, re-flash. After a name change, "Forget This Device" on the iPhone and pair again.

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Hardware

• A classic ESP32 with Classic Bluetooth — not an ESP32-C3/C6/H2 (those are BLE-only). Set board in platformio.ini (default wemos_d1_mini32; a generic module also works as esp32dev).
• A USB cable.

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Build & flash (PlatformIO)

pio run                 # build
pio run -t erase        # (recommended on first flash) wipe old pairings
pio run -t upload       # flash the ESP32
pio device monitor      # serial logs at 115200 baud

The serial port is auto-detected; set upload_port / monitor_port in platformio.ini if you have several devices.

This project uses ESP-IDF 5.3.1 with CMake 3.30 (see platformio.ini): the Classic BT HID Device role is disabled in the precompiled Arduino libraries, so ESP-IDF is required. The first build downloads the SDK and is slow.

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iPhone setup

1) Pair (once)

1. Flash the firmware and power the ESP32.
2. iPhone → Settings → Bluetooth → tap the device under Other Devices (pairs with no code, "Just Works") → it moves to My Devices.

2) Create the automation (Shortcuts app)

1. Shortcuts app → Automation tab → + → Create Personal Automation.
2. Bluetooth → Device → select your device → Next.
3. Add the actions you want → Next → turn off "Ask Before Running" → Done.

From now on, every time the ESP32 powers up and connects, the automation runs. Very useful with Home Assistant Automations.

Notes

• Reconnect is handled by the ESP32: it calls back the last paired iPhone (from the saved-devices list, which persists across reboots). Interval: RECONNECT_PERIOD_S in src/main.cpp.
• On-screen pointer: with a mouse iOS shows the AssistiveTouch cursor; the on-screen keyboard remains usable.
• The red/yellow BT_BTM / BT_HCI lines during connection are normal bluedroid log noise, not real errors.

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How it's built

File	Purpose
src/main.cpp	Firmware: Classic BT HID mouse + auto-reconnect
sdkconfig.defaults	Re-enables Classic BT + HID Device in the ESP-IDF stack
platformio.ini	ESP-IDF 5.3.1, CMake 3.30

License

MIT — see LICENSE.