Andy Green wrote:
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Somebody in the thread at some point said:
| Forwarded from the community list. Can anyone confirm that our code does
| not care what brand the battery is?
If there is suitable power available, the PMU will try to charge
anything on the battery connector without trying to figure out what it
is. Because the charging algorithm is adaptive to how the battery is
reacting, that isn't as dangerous as it sounds.
Hi Andy,
To further understand this, and to make sense of all the suggestions on
the community list about how to charge a dead battery, I'd like to
understand the PMU activity better.
At what point does the PMU start charging? I.e., if the phone is turned
off and USB power is applied, will the PMU start charging? Or does it
require some running code to enable the PMU?
If the latter, is this code in u-boot? Is the PMU enabled in either/both
u-boot in NOR FLASH and NAND FLASH (depending on u-boot version, of course)?
Is it true that while in u-boot (version dependent?), the FR consumes
less than 100mA, so that if powered by any USB source (prior to any USB
negotiation for higher current), the FR can sit in u-boot and charge the
battery with whatever current is left over after keeping the phone running?
Does any USB high current (500mA) negotiation take place in u-boot?
Do we sense the ID resistor in u-boot?
I presume that these two negotiations only occur after we boot into
Linux, so that in u-boot the best we can do is draw 100mA, and charge
with whatever is leftover.
I think you see what I'm trying to understand here. On the community
list are various suggestions of sequences to get a dead battery charged.
I want to understand the underlying process, so that I can document the
correct sequence.
Michael
