19.2.4 Threshold Reference for Internal analog comparator
An external resistor used in conjunction with the Current Source can be used as threshold reference for internal analog
comparator (see Section 20. “Analog Comparator” on page 225). This can be connected to AIN0 (negative analog compare
input pin) as well as AIN1 (positive analog compare input pin). Using a resistor in series with a lower tolerance than the
current source accuracy (≤ 2%) is recommended. Table 19-2 gives an example of threshold references using standard
values of resistors.
19.3 Control Register
19.3.1 ADC control and status register B– ADCSRB
Bit
7
6
5
4
-
3
ADTS3
R/W
0
2
ADTS2
R/W
0
1
ADTS1
R/W
0
0
ADHSM ISRCEN AREFEN
ADTS0 ADCSRB
Read/Write
Initial Value
R/W
0
R/W
0
R/W
0
R
0
R/W
0
• Bit 6 – ISRCEN: Current Source Enable
Set this bit to source a 100µA current to the AREF pin.
Clear this bit to disconnect.
• Bit 5 – AREFEN: Analog Reference pin Enable
Set this bit to connect the internal AREF circuit to the AREF pin.
Clear this bit to disconnect the internal AREF circuit from the AREF pin.
224
ATmega16/32/64/M1/C1 [DATASHEET]
7647O–AVR–01/15
MICROCHIP [ MICROCHIP ]
