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ATtiny10/11/12

Analog Comparator

The Analog Comparator compares the input values on the positive input PB0 (AIN0) and negative input PB1 (AIN1). When

the voltage on the positive input PB0 (AIN0) is higher than the voltage on the negative input PB1 (AIN1), the Analog Com-

parator Output (ACO) is set (one). The comparator’s output can trigger a separate interrupt, exclusive to the Analog

Comparator. The user can select interrupt triggering on comparator output rise, fall or toggle. A block diagram of the com-

parator and its surrounding logic is shown in Figure 26.

Figure 26. Analog Comparator Block Diagram.

Analog Comparator Control and Status Register – ACSR

Note: AINBG is only available in ATtiny12.

• Bit 7 - ACD: Analog Comparator Disable

When this bit is set (one), the power to the Analog Comparator is switched off. This bit can be set at any time to turn off the

Analog Comparator. When changing the ACD bit, the Analog Comparator Interrupt must be disabled by clearing the ACIE

bit in ACSR. Otherwise an interrupt can occur when the bit is changed.

•

Bit 6 - AINBG: Analog Comparator Bandgap Select in ATtiny12

In ATtiny12, when this bit is set, a fixed bandgap voltage of 1.22 ± 0.05V replaces the normal input to the positive input

(AIN0) of the comparator. When this bit is cleared, the normal input pin PB0 is applied to the positive input of the

comparator.

•

Bit 6- Res: Reserved bit in ATtiny10/11

This bit is a reserved bit in the ATtiny10/11 and will always read as zero.

•

Bit 5 - ACO: Analog Comparator Output

ACO is directly connected to the comparator output.

•

Bit 4 - ACI: Analog Comparator Interrupt Flag

This bit is set (one) when a comparator output event triggers the interrupt mode defined by ACI1 and ACI0. The Analog

Comparator Interrupt routine is executed if the ACIE bit is set (one) and the I-bit in SREG is set (one). ACI is cleared by

hardware when executing the corresponding interrupt handling vector. Alternatively, ACI is cleared by writing a logic one to

the flag.

Bit 76543210

$08 ACD (AINBG) ACO ACI ACIE - ACIS1 ACIS0 ACSR

Read/Write R/W R(/W) R R/W R/W R R/W R/W

Initial value 0 0 X 0 0 0 0 0

INTERNAL

VOLTAGE

REFERENCE

(ATtiny12 ONLY)

MUX

AINBG

Atmel AVR ATtiny10 Series User Manual

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