Datasheet

15.9.1. TC0 Control Register A
When addressing I/O Registers as data space using LD and ST instructions, the provided offset must be
used. When using the I/O specific commands IN and OUT, the offset is reduced by 0x20, resulting in an
I/O address offset within 0x00 - 0x3F.
Name: TCCR0A
Offset: 0x44
Reset: 0x00
Property: When addressing as I/O Register: address offset is 0x24
Bit 7 6 5 4 3 2 1 0
COM0A1 COM0A0 COM0B1 COM0B0 WGM01 WGM00
Access
R/W R/W R/W R/W R/W R/W
Reset 0 0 0 0 0 0
Bits 7:6 – COM0An: Compare Output Mode for Channel A [n = 1:0]
These bits control the Output Compare pin (OC0A) behavior. If one or both of the COM0A[1:0] bits are
set, the OC0A 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 OC0A pin must be set in order to
enable the output driver.
When OC0A is connected to the pin, the function of the COM0A[1:0] bits depends on the WGM0[2:0] bit
setting. The table below shows the COM0A[1:0] bit functionality when the WGM0[2:0] bits are set to a
normal or CTC mode (non- PWM).
Table 15-3. Compare Output Mode, non-PWM
COM0A1 COM0A0 Description
0 0 Normal port operation, OC0A disconnected.
0 1 Toggle OC0A on Compare Match.
1 0 Clear OC0A on Compare Match.
1 1 Set OC0A on Compare Match .
The table below shows the COM0A[1:0] bit functionality when the WGM0[1:0] bits are set to fast PWM
mode.
Table 15-4. Compare Output Mode, Fast PWM
(1)
COM0A1 COM0A0 Description
0 0 Normal port operation, OC0A disconnected.
0 1 WGM02 = 0: Normal Port Operation, OC0A Disconnected
WGM02 = 1: Toggle OC0A on Compare Match
1 0 Clear OC0A on Compare Match, set OC0A at BOTTOM (non-inverting mode)
1 1 Set OC0A on Compare Match, clear OC0A at BOTTOM (inverting mode)
Note:
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
139