Functional Description Of The Timer - Altera cyclone V Technical Reference

23-2

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 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 (
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
timer1loadcount
• Timer is enabled after being reset or disabled
• Timer counts down to 0
Altera Corporation
Reset
Manager
Clock
Manager
L4 Peripheral Bus (osc1_clk)
register. The following events can cause a timer to load the initial count from the
register: †
Timer
Interrupt
Interrupt and
System Reset Control
Register Block
Slave Interface
timer1loadcount
MPU
). Reloads the user-defined count
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2016.10.28
Timer