While there are a couple of pretty good Bluetooth and WiFi solutions out there, which keeps your Android smartphone protected while not connected to a Bluetooth device or WiFi nearby, these solutions disable the PIN or password entry on the smartphone while connected. That's pretty handy, let's say while you are in the car - connected to your hands-free kit, or at home - connected to your W-LAN. However, a very interesting utility - really useful for Pebble smartwatch users - is Pebble Locker. And since Pebble is shipping its Pebble Steel since this week to many new Pebble users, I don't want to forget to recommend this app for your convenience. Unlike other solutions, Pebble Locker is free - if you only use it with your Pebble smartwatch but it also offers general Bluetooth and WiFi options through an in-app purchase.
Pebble Locker uses the Android admin API created by Google to control the lock state and password of the device. After installation from Google Play, Pebble Locker becomes a device administrator and whenever a Pebble connects or disconnects (via Bluetooth), Pebble Locker disables or enables the the lock screen with the PIN or password. Furthermore, Pebble Locker also has the option to lock the device instantly upon disconnect.
As mentioned by Luke Korth, the developer of Pebble Lock, Android's admin API "provides a reasonable amount of functionality such as disabling lock screen widgets and the lock screen camera". However, the way he's using the device admin API, "it does not appear possible to use a pattern lock but only a numeric pin or password". Last but not least, Pebble Locker will not circumvent apps such as corporate E-Mail that require an Android device to have a PIN. as well as Pebble Locker will also not remove the PIN or password on encrypted devices.
All this sounds difficult but for the average user it works straight forward and it's free in the basic Pebble version. I've happily paid the US$ 2.99 and also added my Audi Bluetooth car-kit as well as my HTC Fetch to the list of trusted devices. This means that if my Android smartphones are connected to any of these devices, it doesn't force me to enter the PIN.
Cheers ~ Arne