A000046 Arduino, A000046 Datasheet - Page 158

• Manufacturer Part Number: A000046
• Description: MCU, MPU & DSP Development Tools Uno
• Manufacturer: Arduino
• Series: -r
• Type: MCUr

Specifications of A000046

• Processor To Be Evaluated: ATmega328
• Interface Type: USB, I2C, SPI
• Dimensions: 2.7 in x 2.1 in
• Operating Supply Voltage: 5 V
• Contents: Board
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: ATmega328

17.11 Register Description
17.11.1
8161D–AVR–10/09
TCCR2A – Timer/Counter Control Register A
• Bits 7:6 – COM2A1:0: Compare Match Output A Mode
These bits control the Output Compare pin (OC2A) behavior. If one or both of the COM2A1:0
bits are set, the OC2A output overrides the normal port functionality of the I/O pin it is connected
to. However, note that the Data Direction Register (DDR) bit corresponding to the OC2A pin
must be set in order to enable the output driver.
When OC2A is connected to the pin, the function of the COM2A1:0 bits depends on the
WGM22:0 bit setting.
are set to a normal or CTC mode (non-PWM).
Table 17-2.
Table 17-3
mode.
Table 17-3.
Note:
Bit
(0xB0)
Read/Write
Initial Value
COM2A1
COM2A1
0
0
1
1
0
0
1
1
1. A special case occurs when OCR2A equals TOP and COM2A1 is set. In this case, the Com-
pare Match is ignored, but the set or clear is done at BOTTOM. See
page 150
shows the COM2A1:0 bit functionality when the WGM21:0 bits are set to fast PWM
Compare Output Mode, non-PWM Mode
Compare Output Mode, Fast PWM Mode
COM2A1
R/W
COM2A0
COM2A0
7
0
for more details.
0
1
0
1
0
1
0
1
Table 17-2
COM2A0
R/W
0
6
Description
Normal port operation, OC0A disconnected.
Toggle OC2A on Compare Match
Clear OC2A on Compare Match
Set OC2A on Compare Match
Description
Normal port operation, OC2A disconnected.
WGM22 = 0: Normal Port Operation, OC0A Disconnected.
WGM22 = 1: Toggle OC2A on Compare Match.
Clear OC2A on Compare Match, set OC2A at BOTTOM,
(non-inverting mode).
Set OC2A on Compare Match, clear OC2A at BOTTOM,
(inverting mode).
shows the COM2A1:0 bit functionality when the WGM22:0 bits
COM2B1
ATmega48PA/88PA/168PA/328P
R/W
5
0
COM2B0
R/W
4
0
R
3
0
–
(1)
R
2
–
0
WGM21
R/W
1
0
”Fast PWM Mode” on
WGM20
R/W
0
0
TCCR2A
158