ATMEGA2561V ATMEL [ATMEL Corporation], ATMEGA2561V Datasheet - Page 160

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

Register Description
TCCR1A – Timer/Counter 1
Control Register A
TCCR3A – Timer/Counter 3
Control Register A
TCCR4A – Timer/Counter 4
Control Register A
TCCR5A – Timer/Counter 5
Control Register A
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ATmega640/1280/1281/2560/2561
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The COMnA1:0, COMnB1:0, and COMnC1:0 control the output compare pins (OCnA,
OCnB, and OCnC respectively) behavior. If one or both of the COMnA1:0 bits are writ-
ten to one, the OCnA output overrides the normal port functionality of the I/O pin it is
connected to. If one or both of the COMnB1:0 bits are written to one, the OCnB output
overrides the normal port functionality of the I/O pin it is connected to. If one or both of
the COMnC1:0 bits are written to one, the OCnC output overrides the normal port func-
tionality of the I/O pin it is connected to. However, note that the Data Direction Register
(DDR) bit corresponding to the OCnA, OCnB or OCnC pin must be set in order to
enable the output driver.
When the OCnA, OCnB or OCnC is connected to the pin, the function of the COMnx1:0
bits is dependent of the WGMn3:0 bits setting. Table 83 shows the COMnx1:0 bit func-
tionality when the WGMn3:0 bits are set to a normal or a CTC mode (non-PWM).
• Bit 1:0 – WGMn1:0: Waveform Generation Mode
Combined with the WGMn3:2 bits found in the TCCRnB Register, these bits control the
counting sequence of the counter, the source for maximum (TOP) counter value, and
what type of waveform generation to be used, see Table 82. Modes of operation sup-
ported by the Timer/Counter unit are: Normal mode (counter), Clear Timer on Compare
match (CTC) mode, and three types of Pulse Width Modulation (PWM) modes. For
more information on the different modes, see “Modes of Operation” on page 149.
Bit
(0x80)
Read/Write
Initial Value
Bit
(0x90)
Read/Write
Initial Value
Bit
(0xA0)
Read/Write
Initial Value
Bit
(0x120)
Read/Write
Initial Value
Bit 7:6 – COMnA1:0: Compare Output Mode for Channel A
Bit 5:4 – COMnB1:0: Compare Output Mode for Channel B
Bit 3:2 – COMnC1:0: Compare Output Mode for Channel C
COM1A1
COM3A1
COM4A1
COM5A1
R/W
R/W
R/W
R/W
7
0
7
0
7
0
7
0
COM1A0
COM3A0
COM4A0
COM5A0
R/W
R/W
R/W
R/W
6
0
6
0
6
0
6
0
COM1B1
COM3B1
COM4B1
COM5B1
R/W
R/W
R/W
R/W
5
0
5
0
5
0
5
0
COM1B0
COM3B0
COM4B0
COM5B0
R/W
R/W
R/W
R/W
4
0
4
0
4
0
4
0
COM1C1
COM3C1
COM4C1
COM5C1
R/W
R/W
R/W
R/W
3
0
3
0
3
0
3
0
COM1C0
COM3C0
COM4C0
COM5C0
R/W
R/W
R/W
R/W
2
0
2
0
2
0
2
0
WGM11
WGM31
WGM41
WGM51
R/W
R/W
R/W
R/W
1
0
1
0
1
0
1
0
WGM10
WGM30
WGM40
WGM50
R/W
R/W
R/W
R/W
2549K–AVR–01/07
0
0
0
0
0
0
0
0
TCCR1A
TCCR3A
TCCR4A
TCCR5A