Arria V Hard Processor System Technical Reference Manual

ID 683011
Date 12/02/2022
Public
Document Table of Contents

24.3. Functional Description of the Timer

The 32-bit timer counts down from a programmed value and generates an interrupt when the count reaches zero. The timer has an independent clock input connected to the system clock signal or to an external clock source. †

The timer supports the following modes of operation:

  • Free-running mode—decrementing from the maximum value (0xFFFFFFFF). Reloads maximum value upon reaching zero.
  • User-defined count mode—generates a periodic interrupt. Decrements from the user-defined count value loaded from the timer1 load count register (timer1loadcount). Reloads the user-defined count upon reaching zero.

The initial value for the timer (that is, the value from which it counts down) is loaded into the timer by the timer1loadcount register. The following events can cause a timer to load the initial count from the timer1loadcount register: †

  • Timer is enabled after being reset or disabled
  • Timer counts down to 0