233
ATmega16M1/32M1/64M1 [DATASHEET]
8209E–AVR–11/2012
Bit 6 – ADSC: ADC Start Conversion Bit
Set this bit to start a conversion in single conversion mode or to start the first conversion in free running mode.
Cleared by hardware when the conversion is complete. Writing this bit to zero has no effect.
The first conversion performs the initialization of the ADC.
Bit 5 – ADATE: ADC Auto trigger Enable Bit
Set this bit to enable the auto triggering mode of the ADC.
Clear it to return in single conversion mode.
In auto trigger mode the trigger source is selected by the ADTS bits in the ADCSRB register. See
Table 21-7 on Bit 4 – ADIF: ADC Interrupt Flag
Set by hardware as soon as a conversion is complete and the Data register are updated with the conversion result.
Cleared by hardware when executing the corresponding interrupt handling vector.
Alternatively, ADIF can be cleared by writing it to logical one.
Bit 3 – ADIE: ADC Interrupt Enable Bit
Set this bit to activate the ADC end of conversion interrupt.
Clear it to disable the ADC end of conversion interrupt.
Bit 2:0 – ADPS[2:0]: ADC Prescaler Selection Bits
These three bits determine the division factor between the system clock frequency and input clock of the ADC.
21.10.4
ADCSRB – ADC Control and Status Register B
Bit 7 – ADHSM: ADC High Speed Mode
Writing this bit to one enables the ADC High Speed mode. Set this bit if you wish to convert with an ADC clock fre-
quency higher than 200kHz.
Bit 6 – ISRCEN: Current Source Enable
Set this bit to source a 100A current to the AREF pin.
Clear this bit to use AREF pin as Analog Reference pin.
Table 21-6.
ADC prescaler selection.
ADPS[2:0]
Division factor
000
2
001
2
010
4
011
8
100
16
101
32
110
64
111
128
Bit
7
654
3
2
1
0
ADHSM
ISRCEN
AREFEN
-
ADTS3
ADTS2
ADTS1
ADTS0
ADCSRB
Read/Write
R/W
R
R/W
Initial Value
0