Legacy Document

Inside Macintosh: Devices /

Chapter 6 - Power Manager / Power Manager Reference

Power Manager Dispatch Routines / Getting Information About the Internal Batteries

GetBatteryVoltage

You can use the GetBatteryVoltage function to find out the battery voltage.

Fixed GetBatteryVoltage(short whichBattery);

whichBattery

The battery for which you want a voltage reading.

DESCRIPTION

The GetBatteryVoltage function returns the battery voltage as a fixed-point number.

The value of whichBattery should be in the range 0 to BatteryCount()-1. If the value of whichBattery is out of range, or the selected battery is not installed, GetBatteryVoltage will return a result of 0.0 volts.

ASSEMBLY-LANGUAGE INFORMATION

The trap is _PowerMgrDispatch ($A09E). The selector value for GetBatteryVoltage is 27 ($1B) in the low word of register D0. The battery number is passed in the high word of register D0. The 32-bit value of the battery voltage is returned in register D0.