2.1.4. Low battery handling

Two inputs are provided to the ARM926PXP development chip to facilitate software implementation of low battery and emergency power failure situations. These are:

BATOK

This input is an alternate function of GPIO3[7] and tells the software that there is sufficient charge in the battery for normal operation. When this input is inactive the system must not move into an operating mode that requires higher power consumption.

See the ARM PrimeCell GPIO (PL061) Technical Reference Manual for details on enabling alternate functions.

PWRFAIL

This primary input to the interrupt controller signals an emergency power failure. Software must respond immediately by:

  • switching off any high power consumption peripherals, such as LCD back lights and displays

  • moving the system from NORMAL to SLOW mode

  • storing important application state

  • placing the system into SLEEP mode.

The ARM926PXP development chip does not implement hardware to facilitate the above functions. It is the responsibility of software to check the BATOK input before raising the systems power consumption.

Software must also handle the PWRFAIL interrupt correctly.

Copyright © 2004, 2006 ARM Limited. All rights reserved.ARM DDI 0287B
Non-Confidential