Datasheet

Table Of Contents
19.11.1. TCCR1A – Timer/Counter1 Control Register A
When using the I/O specific commands IN and OUT, the I/O addresses 0x00 - 0x3F must be used. When
addressing I/O Registers as data space using LD and ST instructions, 0x20 must be added to these offset
addresses.
Name:  TCCR1A
Offset:  0x2F
Reset:  0x00
Property:
 
When addressing I/O Registers as data space the offset address is 0x4F
Bit 7 6 5 4 3 2 1 0
COM1A1 COM1A0 COM1B1 COM1B0 FOC1A FOC1B WGM11 WGM10
Access
R/W R/W R/W R/W W W R/W R/W
Reset 0 0 0 0 0 0 0 0
Bits 7:6 – COM1An: Compare Output Mode for Channel A [n = 1:0]
Bits 5:4 – COM1Bn: Compare Output Mode for Channel B [n = 1:0]
The COM1A1:0 and COM1B1:0 control the Output Compare pins (OC1A and OC1B respectively)
behavior. If one or both of the COM1A1:0 bits are written to one, the OC1A output overrides the normal
port functionality of the I/O pin it is connected to. If one or both of the COM1B1:0 bit are written to one,
the OC1B 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 OC1A or OC1B pin must be set in order
to enable the output driver.
When the OC1A or OC1B is connected to the pin, the function of the COM1n1:0 bits is dependent of the
WGM13:0 bits setting. The table below shows the COM1n1:0 bit functionality when the WGM13:0 bits are
set to a Normal or a CTC mode (non-PWM).
Table 19-2. Compare Output Mode, non-PWM
COM1A1/COM1B1 COM1A0/COM1B0 Description
0 0 Normal port operation, OC1A/OC1B disconnected.
0 1 Toggle OC1A/OC1B on Compare Match.
1 0 Clear OC1A/OC1B on Compare Match (Set output to low
level).
1 1 Set OC1A/OC1B on Compare Match (Set output to high
level).
The next table shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the fast PWM
mode.
Atmel ATmega32A [DATASHEET]
Atmel-8155I-ATmega32A_Datasheet_Complete-08/2016
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