I would to use battery only to permit correct shutdown of the system.
Now all works ok, the battery power the bone and I can query power manager to know when battery on then start the shutdown.
The problem is the follow: How can I recharge the battery? Seem that the power manager don’t charge the battery when it was down voltage.
If the beaglebone requires 5V input, how your beaglebone works with a 3,7V battery?
At the moment, I’m powering the beagle with a 7,4V battery and a 5V voltaje regulator.
The P6 connector is designed for a 3.7V lithium battery.
You won't have 5V (even on the USB) but the bone should run fine. At
least till the battery voltage drops to around 3.5V, then the DC-DCs
might start sagging on the 3.3V outputs.
Do you have an NTC in the battery (the link doesn't look like it)?
If not, have you cheated the NTC sense lines so the PMIC (power
management IC, the TPS65217) thinks there's an NTC and it's reading room
temp?
What (if any) changes to the PMIC registers are you performing?
How do you know that the battery isn't charging?
Thanks Andrew for your answer.
Yes, my battery don’t have the NTC. I connect a resistor of 10k ohm to simulate this NTC.
So the PMIC indicate in his CHGCONFIG0 register that the BATTEMP is ok (0).
I have changed only the charge voltage to 4.2V as specific of my battery, because the default setting in PWIC is 4.10v:
CHGCONFIG2 register setted to 0xc0h .
Battery isn’t charging beacuse only a few microA (70/80) flow into its.
How are you measuring the current?
When are you taking this measurement? For example, are you measuring 1
minute after boot while sitting at u-boot prompt? Or 30 minutes after
boot while sitting at u-boot prompt? Or something else?
Ok, what meter, how is it connected, and how long after power on are
you taking the measurement? What's the resistance of the meter when used
in the mode you're measuring current?
Measurements with a hall effect type sensor may be less likely to
interfere with the charge circuit. My first guess is your meter is
affecting how the PMIC senses the battery. Second guess is you have a
register setting wrong.
I'm going to test with my lithium battery this week, I will let you
know what I find.
If you connect your Bone to an AC power 5V source (NOT USB!) and at
u-boot prompt, change the registers you want to change, then read
register 3 (CHGCONFIG0) execute:
i2c md 24 3 1
what is the result?
For my battery, indicating a charging status I read
08
which decodes to the charger is active an the temp is OK.
I have also cheated the NTC sense with a 10k resistor.
For the first 30 minutes or until the battery hits VPRECHG set in
CHGCONFIG2, the charger should operate in the "precharge" state,
charging at 40 to 50 mA rate. After "precharge" it should switch to
"fast charge" at 400 to 500 mA rate till it hits the voltage level
specified in VOREG in CHGCONFIG2.
I am not measuring the current to the battery with any device. I'm
watching the voltage of the battery over time with a meter to observe
the charging operation. Sadly, it doesn't seem the TPS65217 has any
registers to read the current voltage or charge / discharge rates (TI,
can we consider this a feature request?).
My battery started at 3.83 V at 10:12 am, was at 3.94 V at 11:06 am,
and now is at 4.00 V at 11:25 am. So it's definitely charging.
I've set the cut off at 4.2 V. I assume it'll hit that fairly soon.
Currently the CHGCONFIG0 register still shows a charging state.
Battery feels room temp (measured with my fingers, they're super
accurate!
I am using a 2S lipo battery (7,4V) and an UBEC to down voltage to 5V. Max current of the UBEC its usually more than 3A, which is enough for beaglebone. The UBEC is connected to the 5V input beaglebone.
I am looking to do exaclty what you seem to have already done. Use a Battery to enable an automated, orderly shutdown of the beaglebone once the main 5V supply has been cut. I haven’t quite figured it out though. Can you tell me how you access the power management of the BB?
You talk to the TPS65217 via I2C. But, as to the access point in the kernel, I can’t answer that.Read the datasheet for the TPS65217 to get an idea on how you might be able to handle the loss of power gracefully.
