AM335x backup battery does not charge

yang yang2

Other Parts Discussed in Thread: AM3352, TPS65910

Hi,

I am using SDK08.00.00.00 on am3352 based custom board. MS920SE-FL72E is used as backup battery like reference design. But it seems MS920SE not be charged during main battery is on. The voltage on MS920SE falls down to about 2.2V after several days(At first it is right, the date and time information can be restored right after main battery power down). So is there any suggestion about this problem?

Thanks

Yang

over 8 years ago

0 Biser Gatchev-XID over 8 years ago

TI__Guru**** 393215 points

Hi,

What PMIC are you using?

0 yang yang2 over 8 years ago in reply to Biser Gatchev-XID

Expert 1420 points

Hi, Biser

I am sorry it is TPS65910A31A1 like reference design.

BR

0 Biser Gatchev-XID over 8 years ago in reply to yang yang2

TI__Guru**** 393215 points

You should check the contents of the PMIC register BBCH_REG at address offset 0x39. See Table 6-49 from the TPS65910 Datasheet (www.ti.com/.../tps65910.pdf)

0 yang yang2 over 8 years ago in reply to Biser Gatchev-XID

Expert 1420 points

Hi, Biser

How can I access this register? When I am typing "i2cdump -y 0 0x2d", it only shows "Error: Could not set address to 0x2d: Device or resource busy".

Am I wrong about the way accessing this register?

Thanks

Yang

0 Biser Gatchev-XID over 8 years ago in reply to yang yang2

TI__Guru**** 393215 points

Try doing this from U-boot. In kernel the device driver is blocking access.

0 yang yang2 over 8 years ago in reply to Biser Gatchev-XID

Expert 1420 points

Hi, Biser

Yes you are right. In U-boot I can get the value of this register(0x00), that means battery charge is disabled by default.

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AM335x backup battery does not charge