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Section 24 A/D Converter
Page 1268 of 2108 R01UH0134EJ0400 Rev. 4.00
Sep 24, 2014
SH7262 Group, SH7264 Group
24.4 Operation
The A/D converter uses the successive-approximation method, and the resolution is 10 bits. It has
three operating modes: single mode, multi mode, and scan mode. Switching the operating mode or
analog input channels must be done while the ADST bit in ADCSR is 0 to prevent incorrect
operation. The ADST bit can be set at the same time as the operating mode or analog input
channels are changed.
24.4.1 Single Mode
Single mode should be selected when only A/D conversion on one channel is required.
In single mode, A/D conversion is performed once for the specified one analog input channel, as
follows:
1. A/D conversion for the selected channel starts when the ADST bit in ADCSR is set to 1 by
software, the multi-function timer pulse unit 2, or external trigger input.
2. When A/D conversion is completed, the A/D conversion result is transferred to the A/D data
register corresponding to the channel.
3. After A/D conversion has 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 that remains 1 during A/D conversion is automatically cleared to 0 when A/D
conversion is completed, and the A/D converter becomes idle.
When the operating mode or analog input channel selection must be changed during A/D
conversion, to prevent incorrect operation, first clear the ADST bit to 0 to halt A/D conversion.
After making the necessary changes, set the ADST bit to 1 to start A/D conversion again. The
ADST bit can be set at the same time as the mode or channel selection is switched.