#To read backup battery voltage, charging must be enabled
i2cset -f -y 1 0x4b 0x6d 0x1c
#Have to write to GPBR1, located at I2C address 0x49, register 0x91
i2cset -f -y 1 0x49 0x91 0x90
#Turn on the ADC, write 0x1 to CTRL1
i2cset -f -y 1 0x4a 0x00 0x01
#Enable ADCIN, write 0xff to SW1SELECT_LSB
i2cset -f -y 1 0x4a 0x06 0xff
#Enable ADCIN, write 0xff to SW1SELECT_MSB
i2cset -f -y 1 0x4a 0x07 0xff
#Enable VBAT prescaler, write 0x2 to BCICTL1.
i2cset -f -y 1 0x4a 0x97 0x02
#Start Conversion, write 0x20 to CTRL_SW1
i2cset -f -y 1 0x4a 0x12 0x20
sleep 1
#ADC9
GPCH9_LSB=`i2cget -f -y 1 0x4a 0x49`
echo "GPCH9_LSB is $GPCH9_LSB"
GPCH9_MSB=`i2cget -f -y 1 0x4a 0x4a`
echo "GPCH9_MSB is $GPCH9_MSB"
#ADC12
GPCH12_LSB=`i2cget -f -y 1 0x4a 0x4f`
echo "GPCH12_LSB is $GPCH12_LSB"
GPCH12_MSB=`i2cget -f -y 1 0x4a 0x50`
echo "GPCH12_MSB is $GPCH12_MSB"
let ADC9=`printf %d $GPCH9_LSB`/64+`printf %d $GPCH9_MSB`*4
let ADC12=`printf %d $GPCH12_LSB`/64+`printf %d $GPCH12_MSB`*4
let VAL9=($ADC9*4399)/1000
let VAL12=($ADC12*5865)/1000
echo "ADC9 value is $ADC9 , $VAL9 millivolts Backup Battery
voltage"
echo "ADC12 value is $ADC12 , $VAL12 millivolts Main Battery Voltage"