I notice at first date I get my Surface RT that it didn't use regular trick as magnetic switch. But until now I didn't get how it work. Is it mechanic to detect in foldable area, accelerometer or gyroscope in it?
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How Surface cover detect it open, close or backflip?
- Thread starter hisoft
- Start date
I tried t work this one out myself, and I came to two conclusions,
1. There is a magnet on the left wrist rest. ( this could also keep the cover from opening)
2. Near the connector, there is a little notch in the design of the cover, and I believe this could be a trigger point for the keyboard, I imagine it's like two metal connector touching to provide power to the cover.
These are just theories, if I am wrong I would like to know how this works.
Dane
Magnet based switching would not have worked in certain configurations such as if you prop your surface up on the kickstand to watch a movie and flip the keyboard underneath out of the way, in this setup the keys would be face down and liable to cause input but you dont want them to. The notch would also likely be unreliable for this reason also.
Instead it has been confirmed by microsoft somewhere that there is actually a second accelerometer in the keyboard base (no gyroscope or magnetometer though) which can be used to determine the angle of the keyboard alone, combined with the angle reported by the tablet accelerometer you can work out if the keyboard is in a position in which it can be used or whether to dim the backlight etc. It would also be incredibly easy for MS to integrate this into their existing system, they keyboard and touchpad are both i2c devices, most accelerometers on the market support i2c, all windows 8 tablets to meet certification must use i2c sensors, i2c devices can be daisy chained so a tablet only needs one i2c "port" on its CPU and you can daisy chain a ridiculous number of devices off of it, I think by default 255 but you can then have i2c expanders ontop of that. Dead easy to daisy chain a cheap accelerometer off of the i2c bus already in that cover.
If there is indeed a magnet, this alone could well be used as a more reliable screen lock than accelerometer data alone though, it may well be used for that. Accelerometers by nature are quite noisy and return alot of dodgy data so if you only used accelerometer data for locking the screen in which the 2 sensors report that the keyboard is open at a 15 degree angle and it wont lock for instance. A magnet would also be compatible with 3rd party folio cases.
Instead it has been confirmed by microsoft somewhere that there is actually a second accelerometer in the keyboard base (no gyroscope or magnetometer though) which can be used to determine the angle of the keyboard alone, combined with the angle reported by the tablet accelerometer you can work out if the keyboard is in a position in which it can be used or whether to dim the backlight etc. It would also be incredibly easy for MS to integrate this into their existing system, they keyboard and touchpad are both i2c devices, most accelerometers on the market support i2c, all windows 8 tablets to meet certification must use i2c sensors, i2c devices can be daisy chained so a tablet only needs one i2c "port" on its CPU and you can daisy chain a ridiculous number of devices off of it, I think by default 255 but you can then have i2c expanders ontop of that. Dead easy to daisy chain a cheap accelerometer off of the i2c bus already in that cover.
If there is indeed a magnet, this alone could well be used as a more reliable screen lock than accelerometer data alone though, it may well be used for that. Accelerometers by nature are quite noisy and return alot of dodgy data so if you only used accelerometer data for locking the screen in which the 2 sensors report that the keyboard is open at a 15 degree angle and it wont lock for instance. A magnet would also be compatible with 3rd party folio cases.
There's a magnet (you can find it with a little trouble using anything sufficiently magnetic) but it's very weak. It can't even be properly said to hold the cover closed. Given the accelerometer in the keyboard, I'm not entirely sure why they bothered.
accelerometers are highly noisy sensors. Most apps and such using them filter a range of 10 inputs out into 1 and use that as a more realistic average. Even then it wont be 100% correct and with 2 sensors each with their own inaccuracy, which is also amplified when the tablet is moving your likely to have a scenario where the tablet thinks its keyboard is not fully closed, unlocks itself and starts draining a teeny bit of battery in your bag as you ride the subway to work and the train is hurtling around a corner or something.
With a bit of filtering they are probably clean enough sensors that you could fairly reliably detect the screen being closed but there is still that chance of it over-riding itself.
Also the magnet means that 3rd party companies can make a leather folio case with a magnet in it for instance
OK. Thank Dane Reynolds, SixSixSevenSeven and GoodDayToDie for information. I didn't notice before that cover have magnet (except for it connector). I don't even think the will place it in the middle of cover. Now I checked and found it. I can use regular magnet to turn screen on and off in it area. Then I think it only regular magnetic switch that only work when cover were connected. (because the cover cannot turn screen on or off when connector didn't connect) Maybe this is for power saver by avoid calculate accelerometer data all the time even when in sleep mode.
Well, it's a combo of accelerometer and the magnet. They both don't have the same function. As far as I know, usually magnets are used to turn the screen on and off and then the accelerometer is probably used for the keyboard and stuff. The only reason I can say that the magnets don't work without connecting is that it's a really tiny magnet, but an electromagnet maybe. Anyways, that's just my take on it. I didn't do any research or anything so yeah.