Hardware specifications

Here you will find the hardware specifications for SmartWatch 2, and the full list of Smart Extension APIs supported for SmartWatch 2.

Hardware capabilities

The following table shows the hardware capabilities of SmartWatch 2. These capabilities can be accessed using the Smart Extension APIs. Keep these in mind when designing your app to ensure a good user experience.

Feature SmartWatch 2
Screen type TFT touch screen,

(16-bit, 65,536 colors)

Screen resolution (width x height) 220 x 176 pixels
Screen size (in inches) 1.6-inch screen
Vibrator Yes
Accelerometer Yes
Light sensor Yes
Action key Yes
Back key Yes

Hardware hints and tips

The following section provides hints and tips concerning SmartWatch 2 hardware-related features to keep in mind during your app development.


A SmartWatch is a high performance smart accessory, so it’s important to use the battery power wisely. If your app uses the Control API, consider these recommendations:

  • Avoid sending full screen images when it is not necessary (send partial screen-updates instead).
  • Avoid using Control.SCREEN_STATE_ON.
  • When using a sensor, use SensorInterruptMode.SENSOR_INTERRUPT_ENABLED to only receive sensor data when the sensor has changed.
  • Avoid excessive use of the vibrator.


Before using a sensor, check for the support of the sensor on the accessory with isSensorSupported() method available through SmartExtensionUtils. Take a look at the SampleSensorExtension code example in the Sony Add-on SDK for usage of this method.


The accelerometer is available to the Control app that is currently started. If the control is paused, for example due to that the screen timeout is reached, the power button is pressed or another control app is started, the sensor will also be stopped.

If the control app wants to continue receiving sensor information, it should use SCREEN_STATE_ON, SCREEN_STATE_OFF or SCREEN_STATE_DIM.


The SmartWatch 2 vibrator has the following specifications:

  • A minimum runtime of approximately 250 ms
  • A run-down time of 250 ms
  • A maximum continuous time of six seconds. After six seconds, the vibrator will automatically turn off to conserve battery.

Sensor data

When collecting sensor data, specifically for accelerometer and light sensor, please note the following information:

Sensor data             Details
Accelerometer data Polling speed: 25Hz.

Precision: Minimum delay: 1000ms; Range: -8g to 8g; Resolution: 0.016g

Light sensor data Type: Lux

Resolution: 10

Background process

All SmartWatch 2 apps are run in a service. Android treats services as background processes. Android has a limitation on the number of background processes that can be run simultaneously. When this limit is exceeded, the Android system stops the least recent used process. This can happen even if the SmartWatch 2 app is currently showing on the display, since the Android system is not aware of this.

Normally this is not a problem for SmartWatch 2 apps that are only shown for a short while and that the user is directly interacting with. The helper classes in SmartExtensionUtils also contain some functionality to help a SmartWatch 2 app recover if it was stopped when the user was interacting with an event.

For SmartWatch 2 apps running for a longer time and which should not be interrupted, you can use Service.startForeground() to make the system consider it to be something the user is actively aware of. The side effect is that a notification is shown in the status bar as long as the service is in foreground state.

API compatibility

The following table shows the Smart Extension APIs and API versions supported by SmartWatch 2. When designing your app, you’ll need to ensure that the features you are planning to use are supported by the API.

Smart Extension API Supported on SmartWatch 2
Control API v1.0 Yes
Control API v2.0 Yes
Registration & capabilities API v1.0 Yes
Registration & capabilities API v2.0 Yes
Notification API v1.0 Yes
Notification API v2.0 Yes
Sensor API v1.0 Yes
Widget API v1.0 No
Widget API v3.0 Yes