AT90USB1286-16MU ATMEL [ATMEL Corporation], AT90USB1286-16MU Datasheet - Page 172

• Manufacturer Part Number: AT90USB1286-16MU
• Description: Microcontroller with 64/128K Bytes of ISP Flash and USB Controller
• Manufacturer: ATMEL [ATMEL Corporation]

16.2.1
172
AT90USB64/128
Timing Example
When the modulator is enabled the type of modulation (logical AND or OR) can be selected by
the PORTB7 Register. Note that the DDRB7 controls the direction of the port independent of the
COMnx1:0 bit setting.
Figure 16-3
ate in fast PWM mode (non-inverted) and Timer/Counter0 uses CTC waveform mode with toggle
Compare Output mode (COMnx1:0 = 1).
Figure 16-3. Output Compare Modulator, Timing Diagram
In this example, Timer/Counter2 provides the carrier, while the modulating signal is generated
by the Output Compare unit C of the Timer/Counter1.
The resolution of the PWM signal (OC1C) is reduced by the modulation. The reduction factor is
equal to the number of system clock cycles of one period of the carrier (OC0A). In this example
the resolution is reduced by a factor of two. The reason for the reduction is illustrated in
16-3
high time is one cycle longer than the period 3 high time, but the result on the PB7 output is
equal in both periods.
(FPWM Mode)
at the second and third period of the PB7 output when PORTB7 equals zero. The period 2
(PORTB7 = 0)
(PORTB7 = 1)
(CTC Mode)
(Period)
OC1C
OC0A
clk
PB7
PB7
illustrates the modulator in action. In this example the Timer/Counter1 is set to oper-
I/O
1
2
3
7593A–AVR–02/06
Figure