Download & Play music to smartwatch from cloud, like google drive or dropbox.
Use your space on google drive or drop box for storing the music files. Download the songs to the smart watch and hear music, by connecting any audio device via Bluetooth. The app is independent from smart phone. Internet connection is mandatory for download. It can be ensured by WiFi router or through the connected smart device w internet access or even w a SIM card in the watch, if supported.
A google account is used to sign in into Google Drive.
Alternatively drop box can be accessed.
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WEAR 1.5 application:
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Some smart watches didn't get updated to Wear OS by OEM, f.e. Sony Smart Watch SWR50. There is no easy way to activate google account on this watch. But, the Dropbox API works well on it. The prerequisites, which need to be met are 1. install a web browser 2. install a keyboard. Both applications can easily be found outside the Play Store.
ADB = Android Debug Bridge is used to perform installation on the SWR50.
How to enable keyboard on Wear 1.5 -https://docs.google.com/file/d/0B0a0XyLZjfUxQmdLVDhVTHB2ME0/
ADB shell commands:
adb install -r -g minuum.apk
adb shell ime enable com.whirlscape.minuum/.MinuumKeyboardService
adb shell ime set com.whirlscape.minuum/.MinuumKeyboardService