ATMEGA128-16AU SL383 Atmel, ATMEGA128-16AU SL383 Datasheet - Page 161

• Manufacturer Part Number: ATMEGA128-16AU SL383
• Manufacturer: Atmel

Output
Compare
Modulator
(OCM1C2)
Overview
Description
2467S–AVR–07/09
The Output Compare Modulator (OCM) allows generation of waveforms modulated with a carrier
frequency. The modulator uses the outputs from the Output Compare Unit C of the 16-bit
Timer/Counter1 and the Output Compare Unit of the 8-bit Timer/Counter2. For more details
about these Timer/Counters see
on page 112
available in ATmega103 compatibility mode.
Figure 72. Output Compare Modulator, Block Diagram
When the modulator is enabled, the two output compare channels are modulated together as
shown in the block diagram
The Output Compare unit 1C and Output Compare unit 2 shares the PB7 port pin for output. The
outputs of the Output Compare units (OC1C and OC2) overrides the normal PORTB7 Register
when one of them is enabled (i.e., when COMnx1:0 is not equal to zero). When both OC1C and
OC2 are enabled at the same time, the modulator is automatically enabled.
The functional equivalent schematic of the modulator is shown on
includes part of the Timer/Counter units and the port B pin 7 output driver circuit.
Figure 73. Output Compare Modulator, Schematic
( From Waveform Generator )
( From Waveform Generator )
COM21
COM20
COM1C1
COM1C0
and
Timer/Counter 1
Timer/Counter 2
“8-bit Timer/Counter2 with PWM” on page
PORTB7
D
OC1C
D
D
OC2
Q
Q
Q
(Figure
“16-bit Timer/Counter (Timer/Counter1 and Timer/Counter3)”
DATABUS
72).
OC1C
OC2
Modulator
0
1
146. Note that this feature is not
DDRB7
D
Q
1
0
Figure
OC2 / PB7
ATmega128
OC1C /
Pin
73. The schematic
Vcc
OC2 / PB7
OC1C /
Pin
161