SH7040 Datasheet, PDF (616/923 Pages) Renesas Technology Corp – Renesas 32-Bit Single-Chip RISC Microprocessor SuperH RISC engine Family/SH7040 Series(CPU Core SH-2)

16.4.2 Scan Mode (SCAN=1)
The scan mode is optimal for monitoring analog input of multiple channels (including channel 1).
A/D conversion is started from channel 1 (AN0 for A/D0 and AN4 for A/D1) of the group when
the ADST bit of the A/D control/status register (ADCSR) is set to 1 by the software or external
trigger input.
When multiple channels are selected, A/D conversion of channel 2 (AN1 or AN5) is initiated
immediately after completion of the channel 1 conversion.
To switch modes or analog input channels during A/D conversion, clear the ADST bit to 0 and
stop A/D conversion to avoid malfunction. After switching (mode/channel change and ADST bit
setting can be made at the same time), set ADST bit to 1 to restart A/D conversion from channel 1.
An example of operation when three channels of A/D0 (AN0–2) are selected for A/D conversion
is shown in figure 16.4 (the bit specification in the example is the ADCSR0 register).
1. Set operation mode to scan mode (SCAN=1), set analog channels to AN0–2 (CH1=1, CH0=0)
then start A/D conversion (ADST=1).
2. When A/D conversion for channel 1 is complete, A/D conversion result is transferred to
ADDRA0.
Next, channel 2 (AN1) will automatically be selected and conversion will begin.
3. In the same manner, channel 3 will be converted (AN2).
4. When conversion of all of the selected channels (AN0–AN2) are complete, ADF will become
1 and channel 1 (AN0) will again be selected and conversion will begin.
At this time, if the ADIE bit is set to 1, ADI interrupt request will occur after completing A/D
conversion.
5. Steps (2) to (4) will be repeated while ADST bit is set to 1.
A/D conversion will stop when setting the ADST bit to 0. When setting the ADST bit to 1,
A/D conversion will start again from channel 1 (AN0).
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