How to detect if a tablet is on or off with USB

Jon Bilbao

Other Parts Discussed in Thread: TPS25810, TPS65982

Hello USB Community,

I am trying to figure out how to detect that a tablet is OFF or ON ?

I am using TPS25810 as USB Controller and this device can detect if a tablet (or device) is connected or not to the USB outlet.

I would like to know how to detect that the tablet is ON or OFF, independently of the status of the battery.

Regards,

Jon

over 8 years ago

0 Jimmy Hua over 8 years ago

TI__Guru 50120 points

Hi Jon,

No the TPS25810 cannot detect when the tablet is OFF or ON. The TPS25810 is a 5V DFP controller device that has the ability to perform cable connection detection and plug polarity detection. For more information on this, please refer to Section 7.1.3 and Section 7.3.3.7 in the Datasheet.

Regards,
Jimmy Hua

0 Jon Bilbao over 8 years ago in reply to Jimmy Hua

TI__Intellectual 1425 points

Hi Jimmy,

thanks. Yes, I am aware of this.

I am looking for a way of detecting if the tablet is on or off. Do you know a device, multiple devices, or a discrete solution than can achieve this?

Regards,

Jon

0 Jimmy Hua over 8 years ago in reply to Jon Bilbao

TI__Guru 50120 points

Hi Jon,

I am not aware of any way to tell if the tablet is on or off. How do you plan on connecting an external device to check if tablet is on or not?
I was thinking of recommending the TPS65982 since it also has GPIO control that you can set to trigger on an event.

Regards,
Jimmy Hua

0 Jon Bilbao over 8 years ago in reply to Jimmy Hua

TI__Intellectual 1425 points

Hi Jimmy,

what exactly would trigger if the tablet is tablet is turned on/off?

Which triggering signal should the GPIO detect?

Regards,

Jon

0 Jimmy Hua over 8 years ago in reply to Jon Bilbao

TI__Guru 50120 points

Hi Jon,

The only way I can think of this working is by having the EC on the device end trigger and send a PDIO message over the USB Type-C connection to the TPS65982. This will then enable the PDIO register (0x5C) of the TPS65982 which can be read as the Device/Tablet being ON.

For more information on PDIO Alternate Mode. refer to the following document: http://www.ti.com/lit/an/slva855/slva855.pdf.

Regards,

Jimmy Hua

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How to detect if a tablet is on or off with USB