Which signal should be used for an interface?

[siuping]

Hi,

I'm designing an external device which output a signal to the phone. A daemon program ensures the continuity of the signal and reports error if the signal is broken or cannot be detected.

I'm considering either using the battery charging or other data signal available to the phone. If using the battery charging approach, the external device is supposed to output a 3.7V DC current for charging up the phone battery. But looking at previous threads in the forum, seems the detection of the battery charging comes with only 3 status. And it may only refresh the status whenever power on the phone.

Anyone knows the battery status if the phone is fully charged but the
charging device is keep connected? Or make use of the DCE Tx/Rx ?

Thanks in advance.

[ivey]

Hi,

You can get more detailed info about battery charge level with AT-command AT+CBC. You get a response in the following form: +CBC: <bcs>,<bcl>. It means (from 3GPP TS 27.007 V7.0.0 (2006-03) spec):

<bcs>:
0 MT is powered by the battery
1 MT has a battery connected, but is not powered by it
2 MT does not have a battery connected
3 Recognized power fault, calls inhibited
<bcl>:
0 battery is exhausted, or MT does not have a battery connected
1...100 battery has 1 100 percent of capacity remaining

I hope it helps you a bit...