ATMEGA640 datasheet(287/436 Pages) MICROCHIP

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ATmega640/V-1280/V-1281/V-2560/V-2561/V [DATASHEET]

DS40002211A

26.8.5

ADCSRB – ADC Control and Status Register B

• Bit 7 – Res: Reserved Bit

This bit is reserved for future use. To ensure compatibility with future devices, this bit must be written to zero when

ADCSRB is written.

• Bit 2:0 – ADTS2:0: ADC Auto Trigger Source

If ADATE in ADCSRA is written to one, the value of these bits selects which source will trigger an ADC conversion.

If ADATE is cleared, the ADTS2:0 settings will have no effect. A conversion will be triggered by the rising edge of

the selected Interrupt Flag. Note that switching from a trigger source that is cleared to a trigger source that is set,

will generate a positive edge on the trigger signal. If ADEN in ADCSRA is set, this will start a conversion. Switching

to Free Running mode (ADTS[2:0]=0) will not cause a trigger event, even if the ADC Interrupt Flag is set

Note:

Free running mode cannot be used for differential channels (see chapter “Differential Channels” on page 273).

26.8.6

DIDR0 – Digital Input Disable Register 0

• Bit 7:0 – ADC7D:ADC0D: ADC7:0 Digital Input Disable

When this bit is written logic one, the digital input buffer on the corresponding ADC pin is disabled. The corre-

sponding PIN Register bit will always read as zero when this bit is set. When an analog signal is applied to the

ADC7:0 pin and the digital input from this pin is not needed, this bit should be written logic one to reduce power

consumption in the digital input buffer.

Bit

76543210

(0x7B)

–

ACME

–

MUX5

ADTS2

ADTS1

ADTS0

ADCSRB

Read/Write

R/W

Initial Value

00000000

Table 26-6.

ADC Auto Trigger Source Selections

ADTS2

ADTS1

ADTS0

Trigger Source

Free Running mode

Analog Comparator

External Interrupt Request 0

Timer/Counter0 Compare Match A

Timer/Counter0 Overflow

Timer/Counter1 Compare Match B

Timer/Counter1 Overflow

Timer/Counter1 Capture Event

Bit

765

4321

(0x7E)

ADC7D

ADC6D

ADC5D

ADC4D

ADC3D

ADC2D

ADC1D

ADC0D

DIDR0

Read/Write

R/WR/W

Initial Value

000

0000

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