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105

ATmega32(L)

2503C–AVR–10/02

16-bit Timer/Counter

Timer/Counter1 Control

• Bit 7:6 – COM1A1:0: Compare Output Mode for Channel A

• Bit 5:4 – COM1B1:0: Compare Output Mode for Channel B

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 Reg-

ister (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 COM1x1:0 bits is

dependent of the WGM13:0 bits setting. Table 44 shows the COM1x1:0 bit functionality

when the WGM13:0 bits are set to a normal or a CTC mode (non-PWM).

Table 45 shows the COM1x1:0 bit functionality when the WGM13:0 bits are set to the

fast PWM mode.

Bit 76543210

COM1A1 COM1A0 COM1B1 COM1B0 FOC1A FOC1B WGM11 WGM10 TCCR1A

Read/Write R/W R/W R/W R/W W W R/W R/W

Initial Value00000000

Table 44. 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)

1 2 ... 100 101 102 103 104 105 106 107 108 109 110 ... 312 313

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Rainbow-electronics ATmega32L Bedienungsanleitung Seite 105