Wednesday, December 2, 2009

charging questions on ben nanonote


i sent an email to list for asking following questions, also you can see the following reply messages here.
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When I measured Ben's charging circuit, I have some questions for s/w hacker:

a) how kernel know that the battery charging if done or in charing?
     Using ADIN0 (pin 92) of jz4720 to check voltage of VBAT? this pin is directly connected to battery cell.
     If you use this to judge, how you manage s/w to shut down ben when battery's voltage goes down under 2.94V?
     you can see [1] &[2], to know SHUTDOWN (GPD6) can tell cpu when components U7 [3] found there's a low voltage detected,
     so means that you may need to do something on software to do store & save tasks then turn off device.

b) has anyone used net name called "CHARGE_N" thus GPC27 (pin 69) of jz4720?
    what status did you initial this pin? input or output? have any help to you?
    Why I asked these questions? Please see [4],
ch1 = CHARGE_N / GPC27 of jz4720
 ch2 = pin 1 of U5 SE9016
I am thinking that using this "CHARGE_N" pin(GPC27) [5] as input then you can let cpu known the status if charging is done or not by h/w, not judge only by ADIN0; so then maybe you can code an icon at UI to let user know that the device is at usb charging mode or battery mode.
Sorry I don't know s/w side. Thanks a lot.
Adam

[1] http://downloads.qi-hardware.com/hardware/qi_avt2/v1.0/report/waveforms/lb60/lb60_12.jpg
[2] http://downloads.qi-hardware.com/hardware/qi_avt2/v1.0/report/waveforms/lb60/lb60_waveform_description
[3] http://downloads.qi-hardware.com/hardware/qi_avt2/v1.0/datasheet/U7~BL8506-30NRM.pdf
[4] http://downloads.qi-hardware.com/hardware/qi_avt2/v1.0/report/waveforms/lb60/lb60_3.jpg
[5] http://wiki.qi-hardware.com/wiki/Power_Supply_Circuit

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