Can someone explain how tablets like Nexus 7 detects a magnetic cover closing? I have tried putting magnets over the spots where the magnets in the cover are, but it will not lock. How does the tablet know if it is a cover?

2 Answers 2


It's widely believed that the Nexus 7's magnetic sensor works in an almost-identical fashion to iPads' smart cover; I couldn't find direct information about the N7, but iFixit has a great teardown of the iPad smart cover that goes into detail of how it works.

The Nexus 7 has a magnetic sensor that can tell when a magnet of sufficient pull force is nearby. The sensor is located under the screen near the pogo plug on the bottom-lefthand corner, estimated to be 45mm up from the bottom left corner and 15mm in from the left side.


Your magnets are probably in the wrong place. The Nexus 7's magnetic cover sensor is not along the right-hand edge, where the magnets that hold the cover closed are. It's in the bottom-left corner of the screen, about 2 cm from the left-hand rim of the device, and 4 cm from the bottom rim. Put another way: with the device in the "camera-uppermost" orientation, with the stock home screen displayed, the icon at the left-hand end of the tray is in the right place.

You also need a pretty strong magnet. Most fridge magnets aren't strong enough to trip the reed switch, but a Buckyball will do it (if you can still buy those where you are).

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