Datasheet

Section 17 A/D Converter
Rev. 6.00 Mar. 18, 2010 Page 697 of 982
REJ09B0054-0600
17.5 Operation
The A/D converter operates by successive approximation with 10-bit resolution. It has two
operating modes; single mode and scan mode. When changing the operating mode or analog input
channel, in order to prevent incorrect operation, first clear the bit ADST to 0 in ADCSR. The
ADST bit can be set at the same time as the operating mode or analog input channel is changed.
17.5.1 Single Mode
In single mode, A/D conversion is to be performed only once on the specified single channel. The
operations are as follows.
1. A/D conversion is started when the ADST bit is set to 1, according to software, timer
conversion start trigger, or external trigger input.
2. When A/D conversion is completed, the result is transferred to the corresponding A/D data
register to the channel.
3. On completion of conversion, the ADF bit in ADCSR is set to 1. If the ADIE bit is set to 1 at
this time, an ADI interrupt request is generated.
4. The ADST bit remains set to 1 during A/D conversion. When A/D conversion ends, the ADST
bit is automatically cleared to 0 and the A/D converter enters the wait state.