1.3. Timer Introduction

Two timers are defined as the minimum provided within a system, although this may be expanded easily. The same principle of simple expansion has been applied to the register configuration, allowing more complex timers to be used; these are, from the programmer’s model, compatible with those already defined.

Two modes of operation are available:

Free-running mode

The timer wraps after reaching its zero value, and continues to count down from the maximum value.

Periodic timer mode

The counter generates an interrupt at a constant interval.

Copyright © 1995-1997 ARM Limited. All rights reserved.ARM DDI 0049C