ATMEga64L ATMEL Corporation, ATMEga64L Datasheet - Page 159

• Manufacturer Part Number: ATMEga64L
• Description: 8-bit AVR Microcontroller with 64K Bytes In-System Programmable Flash
• Manufacturer: ATMEL Corporation

Output Compare
Modulator (OCM1C2)
Overview
Description
2490G–AVR–03/04
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 “16-bit Timer/Counter (Timer/Counter1
and Timer/Counter3)” on page 110 and “8-bit Timer/Counter2 with PWM” on page 144.
Note that this feature is not 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 (Figure 72).
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 auto-
matically enabled.
The functional equivalent schematic of the modulator is shown on Figure 73. The sche-
matic 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
Timer/Counter1
Timer/Counter2
PORTB7
D
D
D
OC1C
OC2
Q
Q
Q
DATA BUS
OC1C
OC2
Modulator
0
1
DDRB7
D
ATmega64(L)
Q
1
0
OC2/PB7
OC1C/
Pin
Vcc
OC2 / PB7
OC1C /
Pin
159