Operation; Single Mode; Scan Mode - Renesas H8S Series Hardware Manual

Section 16 A/D Converter
16.4

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, 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.
16.4.1

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 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 converion ends, the ADST
bit is automatically cleared to 0 and the A/D converter enters the wait state.
16.4.2

Scan Mode

In scan mode, A/D conversion is to be performed sequentially on the specified channels (four
channels maximum). The operations are as follows.
1. When the ADST bit is set to 1 by software, TPU or external trigger input, A/D conversion
starts on the first channel in the group (AN0 when CH3 and CH2 = 00, AN4 when CH3 and
CH2 = 01, or AN8 when CH3 and CH2 = 10).
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 flag 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.
4. Steps 2 to 3 are repeated as long as the ADST bit remains set to 1. When the ADST bit is
cleared to 0, A/D conversion stops and the A/D converter enters the wait state.
Rev. 6.00 Mar 15, 2006 page 444 of 570
REJ09B0211-0600