Configuring PMIC backup battery charging circuit in mb1 BCT.
The PMIC’s builtin backup battery charging circuit can be configured using the CNFGBBC register of the PMIC.
The register exists at offset 4 for MAX77620 and MAX20024 parts.
Following configurations can be made:
Bit[0]: Enable backup battery charger
Bit[1:2]: Charging current setting
Bit[3:4]: Charging voltage limit setting
Bit[5]: Lower charging current enable
Bit[6:7]: Ouput resistor selection
Software configuration can be done using the MB1 PMIC cfg file. The file has sections for configuring PMIC registers.
Such sections have type=1 to indicate I2C transaction, i2c-controller-id=<> for instance of I2C controller and slave-add=0x78 for identifying PMIC.
e.g,
T186:
pmic.generic.1.block[ ].type = 1; # I2C Type
pmic.generic.1.block[ ].i2c-controller-id = 4;
pmic.generic.1.block[ ].slave-add = 0x78; # 7BIt:0x3c
T194:
pmic.system.block[ ].type = 1; #I2C
pmic.system.block[ ].controller-id = 4;
pmic.system.block[ ].slave-add = 0x78; # 7BIt:0x3c
T186 platforms:
Software configuration can be done by adding instruction to set the respective bit fields of register 4.
To disable backup battery charger:
1. Update the number of commands
pmic.generic.1.block[0].count = 2;
2. Add instruction to set the value of bit0 to 0 in register 4(CNFGBBC).
pmic.generic.1.block[0].commands[1].0x04.0x01 = 0x0;
Note: The command structure has register_address.bitmask = value; fields
T194 platforms:
Modify MB1 PMIC cfg file tegra194-mb1-bct-pmic-p2888-0001-a04-E-0-p2822-0000.cfg.
To disable backup battery charger:
Add following command under pmic.system.block[2] in the MB1 PMIC cfg file
pmic.system.block[2].commands[1].0x04.0x01 = 0x0;