Datasheet

Section 17 A/D Converter
Rev. 3.00 Sep. 28, 2009 Page 494 of 710
REJ09B0384-0300
ADIE
ADST
ADF
Set*
Set* Set*
A/D conversion
starts
Clear* Clear*
State of channel 0
(AN0)
State of channel 1
(AN1)
State of channel 2
(AN2)
State of channel 3
(AN3)
Idle
Idle Idle Idle
Idle
Idle
A/D conversion 1 A/D conversion 2
Read the result of conversion
Result of A/D conversion 1 Result of A/D conversion 2
Read the result of conversion
Note : * indicates execution of a software instruction.
ADDRA
ADDRB
ADDRC
ADDRD
Figure 17.2 Example of A/D Converter Operation
(When Channel 1 is Selected in Single Mode)
17.4.2 Scan Mode
In scan mode, A/D conversion is performed sequentially on the specified channels (four channels
or eight channel maximum). Operations are as follows.
1. When the ADST bit in ADCSR is set to 1 by software or an external trigger input, A/D
conversion starts from the first channel of the selected channel. Consecutive A/D conversion of
either four channels maximum (SCANE and SCANS = B'10) or eight channels maximum
(SCANE and SCANS = B'11) can be selected. In the case of consecutive A/D conversion on
four channels, the operation starts from AN0 when CH2 = B'0, and starts from AN4 when
CH2 = B'1. In the case of consecutive A/D conversion on eight channels, the operation starts
from AN0.
2. When A/D conversion for each channel is completed, the result is sequentially transferred to
the A/D data register corresponding to each channel.
3. When conversion of all the selected channels is completed, the ADF bit in ADCSR is set to 1.
If the ADIE bit is set to 1 at this time, an ADI interrupt is requested after A/D conversion ends.
Conversion of the first channel in the group starts again.