ATmega48/88/168
In Free Running mode, a new conversion will be started immediately after the conversion com-
pletes, while ADSC remains high. For a summary of conversion times, see Table 23-1 on page
250.
Figure 23-4. ADC Timing Diagram, First Conversion (Single Conversion Mode)
Next
First Conversion
Conversion
Cycle Number
1
2
12
13
14
15
16
17
18
19
20
21
22
23
24
25
1
2
3
ADC Clock
ADEN
ADSC
ADIF
Sign and MSB of Result
LSB of Result
ADCH
ADCL
MUX and REFS
Update
Conversion
Complete
MUX and REFS
Update
Sample & Hold
Figure 23-5. ADC Timing Diagram, Single Conversion
One Conversion
Next Conversion
1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
3
Cycle Number
ADC Clock
ADSC
ADIF
ADCH
Sign and MSB of Result
LSB of Result
ADCL
Sample & Hold
Conversion
Complete
MUX and REFS
Update
MUX and REFS
Update
Figure 23-6. ADC Timing Diagram, Auto Triggered Conversion
One Conversion
Next Conversion
1
2
3
4
5
6
7
8
9
10
11
12
13
1
2
Cycle Number
ADC Clock
Trigger
Source
ADATE
ADIF
ADCH
ADCL
Sign and MSB of Result
LSB of Result
Sample &
Hold
Prescaler
Reset
Conversion
Complete
Prescaler
Reset
MUX and REFS
Update
249
2545M–AVR–09/07
ATMEL [ ATMEL ]
