Sean McNeil wrote: > How are things with the battery draining issue and phone lockup? This > causes a bad state where the user cannot charge the battery because they > cannot start the phone, right?
There are two causes: 1) u-boot exceeds the 100mA current budget and thus can cause the system to die if the battery is too weak. This can be fixed in software. I have a proof of concept hack for this, but it still needs to be turned into something one can actually use. 2) The inrush current on our power rails, and in particular IO_3V3 can be too large for the bypass capacitor on VB_SYS, thus causing the power supply to collapse and the PMU to cycle, unless a battery is present. (*) Details are here: http://people.openmoko.org/werner/gta02-chg/ Some boards have capacitors that may just be sufficent. I'm now making some measurements to determine how much exactly we need, and also what impact this has on the inrush current we inflict on the USB host. (*) A battery that's discharged deeply enough can go into cut-off mode, causing it to become completely unresponsive until recharged for a bit. "A bit" depends on the battery type: the GTA01 battery leaves cut-off pretty much upon seeing the first electron, while the GTA02 battery wants to have a few millijoule in its belly before it's willing to talk to the world again. There's also the issue of VB_SYS breaking down when enabling the charger while there is no battery. We haven't analyzed that one completely yet, but it seems to be caused by inrush current as well. Making sure the VB_SYS bypass capacitor is large enough solves this as well. - Werner
