ATmega16 datasheet(78/357 Pages) ATMEL

78 / 357 page

2466S–AVR–05/09

ATmega16(L)

In fast PWM mode, the compare unit allows generation of PWM waveforms on the OC0 pin. Set-

ting the COM01:0 bits to 2 will produce a non-inverted PWM and an inverted PWM output can

be generated by setting the COM01:0 to 3 (See Table 40 on page 84). The actual OC0 value will

only be visible on the port pin if the data direction for the port pin is set as output. The PWM

waveform is generated by setting (or clearing) the OC0 Register at the compare match between

OCR0 and TCNT0, and clearing (or setting) the OC0 Register at the timer clock cycle the coun-

ter is cleared (changes from MAX to BOTTOM).

The PWM frequency for the output can be calculated by the following equation:

The N variable represents the prescale factor (1, 8, 64, 256, or 1024).

The extreme values for the OCR0 Register represents special cases when generating a PWM

waveform output in the fast PWM mode. If the OCR0 is set equal to BOTTOM, the output will be

a narrow spike for each MAX+1 timer clock cycle. Setting the OCR0 equal to MAX will result in a

constantly high or low output (depending on the polarity of the output set by the COM01:0 bits.)

fOCnPWM

clk_I/O

N 256

⋅

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ATmega16 Datasheet(PDF) 78 Page - ATMEL Corporation