RCOrientation-Android

Android controller app for sending a phone's orientation to one or more STM32WB boards over Bluetooth Low Energy.

This is the companion app for RCOrientation-STM32WB. The phone computes its own orientation, sends relative roll / pitch / yaw commands to each connected receiver, and displays servo feedback reported by the boards.

Current status

Working prototype:

• reads phone orientation from Android's rotation-vector sensor
• lets the user zero the current pose
• streams relative roll, pitch, and yaw to every connected STM32WB
• requests a high-priority BLE connection, asks Android for 10 ms sensor samples, and sends one orientation update for each fresh sensor sample for responsive bench testing
• supports multiple connected boards
• uses a device-selection mode for already paired receivers
• receives servo-position feedback from each board
• requires BLE pairing in Android Bluetooth settings before the encrypted control channel can operate

Requirements

• Android phone with BLE and a rotation-vector sensor
• Android Studio for development
• companion STM32WB firmware: RCOrientation-STM32WB

Tested during development on a Motorola Edge 50 Neo.

BLE protocol

Service UUID: 7B5D0000-6A2E-4D6B-9E6F-8D2B7C5A1100

Characteristic	Direction	Properties	Size
0x0001 Orientation command	phone -> STM32WB	encrypted write / write without response	8 bytes
0x0002 Servo feedback	STM32WB -> phone	encrypted read / notify	10 bytes

Orientation command payload:

int16_t roll_cdeg;
int16_t pitch_cdeg;
int16_t yaw_cdeg;
uint16_t sequence;

Servo feedback payload:

int16_t servo_us[4];
uint16_t sequence;

Current behavior

• Roll, pitch, and yaw are shown live on screen.
• Zero defines the current phone pose as the neutral reference.
• Device-selection mode shows paired receivers; normal operation hides that list once boards are chosen.
• The app can connect to more than one board.
• New receivers should be paired from Android Bluetooth settings before opening the app.
• Connected boards all receive the same orientation packet.
• Connected boards report their latest servo positions back to the app.
• The UI is locked to portrait mode so control gestures do not recreate the activity and drop BLE links.

Build

Open the project in Android Studio and run it on a real phone, or build from the command line:

.\gradlew.bat :app:assembleDebug

If JAVA_HOME is not configured on Windows, use Android Studio's bundled JDK for the current shell:

$env:JAVA_HOME='C:\Program Files\Android\Android Studio\jbr'
.\gradlew.bat :app:assembleDebug

GitHub Actions also builds the Android project on every push and pull request.

Security note

The companion receiver requires bonded encrypted BLE access. Pair receivers from Android Bluetooth settings before selecting them in the app.

Related project

• STM32WB firmware: RCOrientation-STM32WB