functioning of lid or hall switch

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gurmeet singh
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functioning of lid or hall switch

Post by gurmeet singh »

lid/hall switch. ...
Do you know how laptop goes to stand buy mode when we close laptop screen.???
It is because of this lid switch...( It will be a magnetic , mechanical and opto coupler)
Which let the laptop know what is a status of laptop flap or cover .... and enters in sleep states to save power .
It depends upon the manufacture or designer... how to use this Hall Switch.
In some case lid switch will not affect switching process (where as only back light of led/LCD is turned off only) in some cases it effects the switching process. (It may b enter in any sleep state mostly slp3 state ...)
Lid out is an active low signal and activates when low. It must be high to turn on the board .

In normal conditions lid out will be high 3.3v, when top cover of laptop is closed, Lid switch or hall switch sends the lid_close#(low) signal to the i/o controller . Whenever there is a input a response to it is must, then I/O sends the ec_lid_out# signal to ich/pch. Where the internal resisters of ich/pch(which are used to monitor, the events occurring) resets And system enters to spl_s3 state . In newer kind of boards lid# for I/O is present but the output to this response may not b a hard coded signal as ec_lid_out#.
There is SCI (system control interrupt) is used between I/O controller and pch to create this event.
nikul patel
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Re: functioning of lid or hall switch

Post by nikul patel »

sir , lenovo laptop lcd ki brightness bahot kum he, usko badhane ke liye knowledge tips ,plz
dspok
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Re: functioning of lid or hall switch

Post by dspok »

Nikul,

If backlight is completely black then check BL_PWM and BL_EN signal both should be 3.3v

If both signal are present then make sure backlight itself is faulty.
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nimeshpatel
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Re: functioning of lid or hall switch

Post by nimeshpatel »

Nice explain about lid out signal.Thanks for sharing
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