AT94K datasheet(97/192 Pages) ATMEL

97 / 192 page

AT94K Series FPSLIC

Rev. 1138F–FPSLI–06/02

Timer/Counter1 Control Register A – TCCR1A

• 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 CompareA pin

PE6. 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 26.

• 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 CompareB pin

PE5. 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 following control configuration is given:

Notes:

1. In PWM mode, these bits have a different function. Refer to Table 30 for a detailed

description.

2. X = A or B

• Bit 3 - FOC1A: Force Output Compare1A

Writing a logic 1 to this bit forces a change in the compare match output pin PE6 according to

the values already set in COM1A1 and COM1A0. If the COM1A1 and COM1A0 bits are written

in the same cycle as FOC1A, the new settings will not take effect until next compare match or

forced compare match occurs. The Force Output Compare bit can be used to change the out-

put pin without waiting for a compare match in the timer. The automatic action programmed in

COM1A1 and COM1A0 happens as if a Compare Match had occurred, but no interrupt is gen-

erated and it will not clear the timer even if CTC1 in TCCR1B is set. The FOC1A bit will always

be read as zero. The setting of the FOC1A bit has no effect in PWM mode.

• Bit 2 - FOC1B: Force Output Compare1B

Writing a logic 1 to this bit forces a change in the compare match output pin PE5 according to

the values already set in COM1B1 and COM1B0. If the COM1B1 and COM1B0 bits are written

in the same cycle as FOC1B, the new settings will not take effect until next compare match or

forced compare match occurs. The Force Output Compare bit can be used to change the out-

put pin without waiting for a compare match in the timer. The automatic action programmed in

COM1B1 and COM1B0 happens as if a Compare Match had occurred, but no interrupt is gen-

erated. The FOC1B bit will always be read as zero. The setting of the FOC1B bit has no effect

in PWM mode.

Bit

765

432

$2F ($4F)

COM1A1

COM1A0

COM1B1

COM1B0

FOC1A

FOC1B

PWM11

PWM10

TCCR1A

Read/Write

R/W

R/w

R/W

Initial Value

000

Table 26. Compare 1 Mode Select(1)

COM1X1

(2)

COM1X0

(2)

Description

Timer/Counter1 disconnected from output pin OC1X

Toggles the OC1X output line

Clears the OC1X output line (to zero)

Sets the OC1X output line (to one)

AT94K Datasheet(PDF) 97 Page - ATMEL Corporation

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