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Section 14 A/D Converter
Bit
Bit Name
1, 0
[Legend]
X:
Don't care
To set A/D conversion to start by the ADTRG0 pin, the DDR bit and ICR bit for the
Note:
*
corresponding pin should be set to 0 and 1, respectively. For details, see section 8, I/O
Ports.
14.4
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, to prevent incorrect operation, first clear the ADST bit in ADCSR to 0 to halt A/D
conversion. The ADST bit can be set to 1 at the same time as the operating mode or analog input
channel is changed.
14.4.1
Single Mode
In single mode, A/D conversion is to be performed only once on the analog input of the specified
single channel.
1. A/D conversion for the selected channel is started when the ADST bit in ADCSR is set to 1 by
software or an external trigger input.
2. When A/D conversion is completed, the A/D conversion result is transferred to the
corresponding A/D data register of the channel.
3. When A/D conversion 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 request is generated.
4. The ADST bit remains set to 1 during A/D conversion, and is automatically cleared to 0 when
A/D conversion ends. The A/D converter enters wait state. If the ADST bit is cleared to 0
during A/D conversion, A/D conversion stops and the A/D converter enters wait state.
Rev.2.00 Jun. 28, 2007 Page 532 of 666
REJ09B0311-0200
Initial
Value
R/W
Description
All 0
R
Reserved
These are read-only bits and cannot be modified.
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