Functional Description Of The Timer; Clocks - Altera Cyclone V Device Handbook

Hide thumbs Also See for Cyclone V:

Table of Contents

Functional Description of the Timer

Figure 23-1: Timer Block Diagram

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

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

Table 23-1: Timer Clock Characteristics

This table shows the clock signals and connections associated with the timers.

OSC1 timer 0

OSC1 timer 1

Altera Corporation

Interrupt and

System Reset Control

Slave Interface

L4 Peripheral Bus (osc1_clk)

System Clock

Timer must be disabled if clock

frequency changes

Timer Introduction

Send Feedback

Table of Contents