TWL6032: Can registers be changed during hardware charging?

Thanks Kevin.

Would explicitly stopping and restarting USB charging also reset the registers?

Also do you mind if I email you directly (I've got your info) or would it be preferred that we communicate via E2E?

Robert

Currently we are writing 0 to CONTROLLER_CTRL1 to disable charging, read the battery voltage, and then continue charging by invoking the normal function to start USB charging. This resets the PMIC registers to default values and I've confirmed that the registers stay intact if 0 is never written to CONTROLLER_CTRL1. 

The code to start USB charging however only executes if not charging, so my experiment also bypasses a number of i2c write commands:

CHARGERUSB_VICHRG

CHARGERUSB_CINLIMI

CHARGERUSB_INT_MASK

CHARGERUSB_CTRL2

CONTROLLER_CTRL1

Is it possible that one of the above commands is causing the PMIC registers to reset?

I don't have an eval board to try this with.

Thanks.

Thanks Kevin for checking on your EVM. I'm doing exactly the same thing: write 0x00 to CONTROLLER_CTRL1 to turn off charging, check battery voltage, then 0x30 to turn charging back on. When this happens my PMIC values are reset. Did you ever do any code review with the original authors of our code or is that out of the scope of your support?

Kevin,

Can you try your test with the EVM again but manipulate CHARGERUSB_VOREG and CHARGERUSB_CTRL1 since these are the 2 in particular that are resetting? VBATMIN_HI_THRESHOLD for example doesn't seem to get reset.

Thanks

Hi Robert,

I can confirm that CHARGERUSB_VOREG is reset but CHARGERUSB_CTRL1 seems to stay the same for me, at least when I set HZ_MODE for example.

Would setting HZ_MODE instead of disabling the charger work for this case? I can confirm that going into and out of HZ_MODE does not reset CHARGERUSB_VOREG.

Regarding software review, it was historically handled by the processor team but due to the age of this processor it is likely not still being supported by them. I can look over the charger related software if you can provide something low level to me (I'm an analog engineer) but hopefully the above can work instead.

Kevin,

I'm also an analog engineer hence the request for code review lol (programmed lots in high school and college but that was a long time ago). But perhaps HZ_MODE will work if it's equivalent to adding a big series resistor to the battery path. I'll try it tomorrow.

Thanks!

Kevin,

Can you confirm which pin goes high Z when invoking HZ_MODE? Is it CHRG_VBAT?

Thanks.

Hi Robert,

HZ_MODE disables Q2 in Figure 4-6 to OFF, disconnecting VBUS from the circuit. This will make VSYS = VBAT; which may or may not be what you are looking for. If your VBAT is not able to stay above VSYSMIN_LO then the part will shut off for example.

Disabling the linear charger (EN_LINCH) was the only way I saw to disable S1 (connection between battery and VSYS) and toggling this bit causes the VOREG register reset. Generally, the following are:

CHRGUSB_VICHRG_PC;

CONTROLLER_CTRL1 (5);

CONTROLLER_WDG (6 downto 0);

CHRGUSB_CTRL2 (7 downto 5);

CHRGUSB_VOREG (5 downto 0);

CHRGUSB_VICHRG (3 downto 0);

If setting EN_CHARGER to 0 instead, it resets the above plus:

CHRGUSB_VSYSREG;

CONTROLLER_CTRL1 (4 downto 3);

CHRGUSB_CTRL1(4);

CHRGUSB_CTRL3(0);

CHRGUSB_CTRL3(1);

CHRGUSB_CTRL3(2);

CHRGUSB_CTRL3(6);

CHRGUSB_CINLIMIT (5 downto 0);

ANTCOLAPSE_CTRL1;

Hopefully that helps.

Kevin,

HZ_MODE has solved my issue of resetting PMIC registers. I'm now able to terminate the charge properly allowing the battery to charge higher than 4.08V. It's OK that VSYS=VBAT when HZ_MODE=1 since that's the behavior I was getting previously when setting CHARGERUSB_CTRL1 to 0x0.

Is the GAS GAUGE the standard way to measure charge capacity/progress? The code currently reports zero for charge current, which perhaps is the reason the original authors are using battery voltage instead.

Robert