ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 174

• Manufacturer Part Number: ATMEGA2561V
• Description: 8-bit Microcontroller with 64K/128K/256K Bytes In-System Programmable Flash
• Manufacturer: ATMEL [ATMEL Corporation]

Output Compare
Modulator
(OCM1C0A)
Overview
Description
174
ATmega640/1280/1281/2560/2561
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/Counter0. For
more details about these Timer/Counters see “Timer/Counter 0, 1, 3, 4, and 5 Prescaler”
on page 172 and “8-bit Timer/Counter2 with PWM and Asynchronous Operation” on
page 176.
Figure 63. Output Compare Modulator, Block Diagram
When the modulator is enabled, the two output compare channels are modulated
together as shown in the block diagram (Figure 63).
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 OC0A) overrides the nor-
mal PORTB7 Register when one of them is enabled (i.e., when COMnx1:0 is not equal
to zero). When both OC1C and OC0A are enabled at the same time, the modulator is
automatically enabled.
The functional equivalent schematic of the modulator is shown on Figure 64. The sche-
matic includes part of the Timer/Counter units and the port B pin 7 output driver circuit.
Figure 64. Output Compare Modulator, Schematic
( From Waveform Generator )
( From Waveform Generator )
COMA01
COMA00
COM1C1
COM1C0
Timer/Counter 1
Timer/Counter 0
PORTB7
D
OC1C
D
OC0A
D
Q
Q
Q
DATABUS
OC1C
OC0A
Modulator
0
1
DDRB7
D
Q
1
0
OC0A / PB7
OC1C /
Pin
2549K–AVR–01/07
Vcc
OC0A/ PB7
OC1C /
Pin