GarageAA to ESP32

GarageAAtoESP32 turns your car's Android Auto display into a one-tap garage door remote, talking directly to your own ESP32-based opener over Bluetooth Low Energy.

No cloud. No subscriptions. No accounts. Your phone talks to your garage and nothing else.

IMPORTANT: you DO NEED to have an ESP32 board set up, this DOES NOT work as a standalone app.
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WHAT IT IS

This app is the companion for a do-it-yourself garage door opener built around an ESP32 microcontroller. You wire the ESP32 to your existing garage motor's push-button input (via a relay or transistor), flash the open-source firmware, and this app becomes your remote — both on your phone and on your car's Android Auto screen.

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KEY FEATURES

• One-tap open from the Android Auto launcher in your car
• One-tap open from your phone home screen
• Direct Bluetooth Low Energy connection — works without internet, without Wi-Fi, without any cloud service
• HMAC-SHA256 challenge-response authentication: your PIN is never transmitted over the air, only used as the key to sign a fresh random nonce each time
• Automatic retry: handles the ESP32 deep-sleep wake window transparently
(up to 3 attempts, 2 s apart)
• Demo mode: try the full Android Auto and phone UI without any hardware

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PRIVACY-FIRST BY DESIGN

• No data is sent to any server, ever
• No analytics, no crash reporting, no advertising SDKs, no third-party tracking
• Your PIN and device address are stored locally in encrypted preferences
(AES-256, Android Keystore)
• Uninstalling the app removes all stored data instantly

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WHAT YOU NEED

• An ESP32 development board (about EUR 5)
• A 5 V relay module or a small NPN transistor + resistor (about EUR 2)
• A USB cable to flash the firmware once
• Access to your garage motor's manual push-button terminals (the same wires the wall button uses)

This is a hardware project. If you have not soldered wires before, this is a
gentle one to start with — but you do need to be comfortable opening the side of your garage motor and connecting two wires to its button input.

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HOW IT WORKS

1. The ESP32 advertises a custom BLE service near your garage.
2. When you tap "Open Garage", the app connects, reads a fresh random nonce from the ESP32, computes HMAC-SHA256(PIN, nonce), and sends the result back.
3. The ESP32 verifies the HMAC; if it matches, it pulses the relay/transistor
for ~500 ms, which is exactly what your garage's wall button does.
4. The ESP32 returns to deep sleep until the next time you drive up.

Because the PIN is only used as a key, never transmitted, eavesdropping on the BLE traffic does not reveal your PIN. Each open uses a new nonce, so replay attacks do not work either.

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ANDROID AUTO

The app appears in your car's Android Auto app launcher under the "Other apps" or IoT section. One screen, one big button: Open Garage. The app does not run while you drive — it is woken when you tap the icon and finishes in a few seconds.

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PERMISSIONS

• Bluetooth Scan / Connect — to find and talk to your ESP32
• Approximate location — required by Android for BLE scanning on older
versions; the app does not use, store, or transmit your location

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NOT AFFILIATED

GarageAAtoESP32 is an independent project. It is not affiliated with Google,
Espressif Systems, or any garage door manufacturer.