Quote:
Originally Posted by DaleDe
All of the ebook readers have something going on in the background when in standby mode. This is due to the need to respond to the power button press. It has to be recognized by the OS in order to start up again. However, there are techniques to minimize the power drain such as slowing down the processor, placing it in sleep mode waking up from time to time to check the power, etc. Jinke knows how to do this as the 6" device works fine.
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Actually there's NOT any need for ANY software to be running at all in order for the POWER button to wake up the unit. There are simple circuits that accomplish this in low power situations. (I worked for Hewlett-Packard in their calculator division from the late 70s through the mid 90s, and had a lot of experience with these kinds of things.) The basic idea is that you have a very high resistance resistor and a capacitor, which hold a pin of the CPU (or the wake-up circuit if the CPU is not designed for it, but I suspect the CPUs used in these readers ARE designed for this) at close to the battery voltage, but with essentially no current flowing (yes, a few electrons dribble out, but it's so little that it's essentially 0). When you press the POWER button, that shorts the far side of the resistor from the battery to GROUND, which drops that 'point' in the circuit from near battery voltage to 0 volts, which turns on a power-transistor that applies power to the rest of the device (or at least, enough of it to get the CPU and ROM running so that everything else can be brought up).
But, if there's a periodic timer that Jinke left runing (left power to) that generates a power-up interrupt, or actually left a program running that prevented the CPU from shutting down, that would definitely explain things. And I now believe that something along that line IS the cause of much of these battery problems, as my problem went away when I did two things:
1) removed my SD card
2) updated my firmware to Jinke's latest (Oct 15th) build
It lasted 11 days before it dropped from 4 bars to 3 (when before that would happen after 2-3 days at most). All indications are, from what we're hearing and what we're seeing, that it was the firmware update that did this, not the SD card removal. I'm now 1 1/2 days into a second test with the SD card back in and the unit fully charged, to verify that it was the firmware update that fixed things. If it's still at 4 bars Saturday morning (that'll be 4 full days), I'll be 100% convinced.