atmega103 ATMEL Corporation, atmega103 Datasheet - Page 49

• Manufacturer Part Number: atmega103
• Description: Atmega103 8-bit With 128k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Timer/Counter1 Control
Register A – TCCR1A
0945I–AVR–02/07
If the Noise Canceler function is enabled, the actual trigger condition for the capture
event is monitored over four samples, and all four must be equal to activate the capture
flag.
• Bits 7..6 – COM1A1, COM1A0: Compare Output Mode1A, Bits 1 and 0
The COM1A1 and COM1A0 control bits determine any output pin action following a
compare match in Timer/Counter1. Any output pin actions affect pin OC1A – Output
Compare A pin 1. This is an alternative function to an I/O port, and the corresponding
direction control bit must be set (one) to control an output pin. The control configuration
is shown in Table 15
• Bits 5..4 – COM1B1, COM1B0: Compare Output Mode1B, Bits 1 and 0
The COM1B1 and COM1B0 control bits determine any output pin action following a
compare match in Timer/Counter1. Any output pin actions affect pin OC1B – Output
Compare B. Since this is an alternative function to an I/O port, the corresponding direc-
tion control bit must be set (one) to control an output pin. The control configuration is
given in Table 15.
Table 15. Compare1 Mode Select
Note:
• Bits 3..2 – Res: Reserved Bits
These bits are reserved bits in the ATmega103(L) and always read as zero.
• Bits 1..0 – PWM11, PWM10: Pulse Width Modulator Select Bits
These bits select PWM operation of Timer/Counter1 as specified in Table 18 on page
53. This mode is described on page 53.
Table 16. PWM Mode Select
Bit
$2F ($4F)
Read/Write
Initial Value
COM1X1
PWM11
0
0
1
1
0
X = A or B.
In PWM mode, these bits have a different function. Refer to Table 16 for a detailed
description.
COM1A1
R/W
7
0
COM1X0
PWM10
0
1
0
1
0
COM1A0
R/W
6
0
Description
Timer/Counter1 disconnected from output pin OC1X
Toggle the OC1X output line.
Clear the OC1X output line (to zero).
Set the OC1X output line (to one).
Description
PWM operation of Timer/Counter1 is disabled.
COM1B1
R/W
5
0
COM1B0
R/W
4
0
R
3
–
0
R
2
–
0
ATmega103(L)
PWM11
R/W
1
0
PWM10
R/W
0
0
TCCR1A
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