ATPL00B datasheet(53/152 Pages) ATMEL

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Atmel ATPL00B [datasheet]

43028A-ATPL - 9/12

Table 5-1.

Timer 2 operating modes

Mode

T2CON(5)

T2CON(4)

CP/RL2

T2OE

Auto-reload

Programmable

clock-out

Capture

stopped

Baud Rate

generator

Timer 2 operation is similar to timer 0 and timer 1. C/T2 selects between timer operation mode (internal clock input) or

counter operation mode (external pin T2 as the time register input). Setting TR2 allows TL2 to be incremented by the

selected input.

The timer 2 related interrupt flags (TF2, EXF2) can be configured to be cleared by hardware when the interrupt routine

is vectored to, or by user software using TF2SC and EXF2SC.

The operating modes are described in the following paragraphs.

5.2.2

Capture mode

In the capture mode, timer 2 operates as a 16-bit timer or counter. An overflow condition sets bit TF2, which can be

used to request an interrupt. Setting the external enable bit EXEN2 allows the RCAP2H and RCAP2L registers to

capture the current value in timer registers TH2 and TL2 in response to a 1-to-0 transition at external input T2EX. The

transition at T2EX also sets bit EXF2 in T2CON. The EXF2 bit, like TF2, can generate an interrupt.

Figure 5-3.

Timer 2 capture mode

5.2.3

Auto-Reload mode

The auto-reload mode configures timer 2 as a 16-bit timer or event counter with automatic reload. The timer operates as

an up counter or as an up/down counter, as determined by the down counter enable bit (DCEN). When reset occurs,

DCEN is cleared, so in the auto-reload mode, timer 2 in configured as an up counter by default.

RCAP

CLK

1/(3 x (T2PR(1:0) + 1))

TL2

TF2

„1‟

„0‟

T2 pin

TR2

C/T2

Interrupt

Control

Hardware

RCAP

TH2

EXF2

T2EX pin

EXEN 2

ATPL00B Datasheet(PDF) 53 Page - ATMEL Corporation

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