Data Points

An app that collects and records device sensor readings to CSV file on Android periodically in background.

For every day a new CSV file is recorded to:

/<internal_storage>/<csv_relative_path>/<date_iso_8601>_<device_name>.csv

• <csv_relative_path> is typically SensorDataPoints folder - to change, see Configure below
• <device_name> is the user-editable device name in Android settings

Example: /sdcard/SensorDataPoints/2023-12-25_MyPhone.csv

Data structure

CSV field header	Unit/Format	Note
Date	ISO 8601 date	yyyy-MM-dd Example: 2023-12-25
Time	ISO 8601 time	HH:mm:ss Example: 17:03:57
Timezone	ISO 8601 offset from UTC	±HHmm Example: +0100
ScreenState	0 or 1	0: device screen is off 1: screen on
BatteryPercent	Percentage
UnlockState	0 or 1	0: device is locked 1: unlocked
Latitude	Degrees
Longitude	Degrees
Pressure	Hectopascals
Bearing	Degrees	Range: 0 until 360
Pitch	Degrees	0: device flat -90: pointing down 90: pointing up
Tilt	Degrees	0: device flat -90: facing left 90: facing right
Acceleration	m/s2	Absolute value regardless of direction 0: device stationary
Temperature	Degrees °C
Lux	Lux
DataPointDuration	Milliseconds	How long it took to collect all readings for current data point

If a reading cannot be obtained, its recorded value will be its CSV field header followed by a suffix depending on the reason:

• NoSensor: app couldn't find the sensor to read the value from
• Missing: the value was not obtained due to denied permission
• Timeout: it took abnormally long to read the value: 25 seconds for location, 2 seconds for other readings

A line of sensor readings is added at every minute to the CSV file of the current day. However, when device is in power saving mode, the app will respect that and skip data points.

Build & install

Requirements:

• Java
• Android SDK

Get the source code

git clone https://github.com/alex-vt/DataPoints
cd DataPoints

Configure

The relative path of folder with CSV files in device internal storage is SensorDataPoints by default.

To override it with a new path, create, or put line to secrets.properties in the project's root folder:

csvRelativePath=<new_path>

Example: csvRelativePath=Documents/Data/CSV

For debug build

The relative path of folder with CSV files in device internal storage is SensorDataPoints-debug by default.

To override it with a new path, create, or put line to secrets.properties in the project's root folder:

csvRelativePathDebug=<new_path>

App signing setup

• Put your keystore.jks to the project's root folder for signing the app.
• Create, or put lines to secrets.properties in the project's root folder with keystore.jks credentials:

signingStoreLocation=../keystore.jks
signingStorePassword=<keystore.jks password>
signingKeyAlias=<keystore.jks alias>
signingKeyPassword=<keystore.jks key password>

For debug build

This step isn't required - debug keystore will be used instead automatically

Install on ADB connected device:

./gradlew app:installRelease

For debug build

./gradlew app:installDebug

Build installable APK:

./gradlew app:assembleRelease

Then install app/build/outputs/apk/release/app-release.apk on Android device.

For debug build

./gradlew app:assembleDebug

Then install app/build/outputs/apk/release/app-debug.apk on Android device.

User manual

Once installed and launched, the app will request permissions:

Permission	If not granted
Location, fine	App will collect data points with missing location
Location, at all times	App will collect data points with missing location when its UI is not opened
Notifications	App will collect data points without visual indication
Files access, all	App will not collect or record data points

Note: notifications will be shown for 5 seconds minimum in order to be seen adequately. Data point collection may complete quicker than that.

The app can be prevented from collecting and recording data points by setting the device to at least one of the following:

• Power saving mode is enabled
• Files access permission is not granted

Once the conditions above are lifted, normal operation resumes.

When launched, the app shows unprocessed CSV records of data points collected on the current day.

License

MIT license.