ATmega162 datasheet(90/324 Pages) ATMEL

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2513K–AVR–07/09

ATmega162/V

The double buffered Output Compare Register (OCR0) is compared with the Timer/Counter

value at all times. The result of the compare can be used by the Waveform Generator to gener-

ate a PWM or variable frequency output on the Output Compare pin (OC0). See “Output

Compare Unit” on page 91. for details. The Compare Match event will also set the Compare Flag

(OCF0) which can be used to generate an output compare interrupt request.

Definitions

Many register and bit references in this section are written in general form. A lower case “n”

replaces the Timer/Counter number, in this case 0. However, when using the register or bit

defines in a program, the precise form must be used i.e., TCNT0 for accessing Timer/Counter0

counter value and so on.

The definitions in Table 46 are also used extensively throughout the document.

Timer/Counter

Clock Sources

The Timer/Counter can be clocked by an internal or an external clock source. The clock source

is selected by the Clock Select logic which is controlled by the Clock Select (CS02:0) bits

located in the Timer/Counter Control Register (TCCR0). For details on clock sources and pres-

caler, see “Timer/Counter0, Timer/Counter1, and Timer/Counter3 Prescalers” on page 104.

Table 46. Definitions

BOTTOM

The counter reaches the BOTTOM when it becomes 0x00.

MAX

The counter reaches its MAXimum when it becomes 0xFF (decimal 255).

TOP

The counter reaches the TOP when it becomes equal to the highest

value in the count sequence. The TOP value can be assigned to be the

fixed value 0xFF (MAX) or the value stored in the OCR0 Register. The

assignment is dependent on the mode of operation.

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