32. 12-Bit A/D Converter (S12AD)
Under development Preliminary document
Specifications in this document are tentative and subject to change.
ADCS[1:0] Bit (Scan Mode Select)
The ADCS bit selects the scan mode.
In single-cycle scan mode, A/D conversion is performed for the analog inputs of a maximum of 16 channels selected
with the ADANSA register in the ascending order of the channel number, and when one cycle of A/D conversion is
completed for all the selected channels, scan conversion is stopped.
In continuous scan mode, while the ADST bit in ADCSR is 1, A/D conversion is performed for the analog inputs of a
maximum of 16 channels selected with the ADANSA register in the ascending order of the channel number, and when
one cycle of A/D conversion is completed for all the selected channels, A/D conversion is repeated beginning at the first
channel. A/D conversion is repeated until the ADST bit in ADCSR is set to 0.
In group scan mode, A/D conversion is performed for the analog inputs (group A) of a maximum of 16 channels selected
with the ADANSA register in the ascending order of the channel number after scanning is started by the MTU or ELC
trigger selected by the TRSA[3:0] bits in ADSTRGR, and when one cycle of A/D conversion is completed for all the
selected channels, A/D conversion is stopped. A/D conversion is also performed for the analog inputs (group B) of a
maximum of 16 channels selected with the ADANSB register in the oscending order of the channel number after
scanning is started by the MTU or ELC trigger celected by the TRSB[3:0] bits in ADSTRGR, and when one cycle of A/
D conversion is completed for all the selected channels, A/D converion is stipped. In group scan mode, different
channels and triggers should be selected for group A and group B.
When the temperature sensor output or the internal reference voltage is selected, single-cycle scan mode should be
selected and all the channels selected by the ADANSA register should be deselected, after which A/D conversion is to be
started. The A/D conversion stops after completion of A/D conversion of the temperature sensor output or the internal
reference voltage selected.
The ADCS bit should be set while the ADST bit is 0 (it should not be set simultaneously when 1 is written to the ADST
bit.)
ADST Bit (A/D Conversion Start)
The ADST bit starts or stops A/D conversion process.
Before the ADST bit is set to 1, set the A/D conversion clock, the conversion mode, and conversion target analog input.
[Setting conditions]
1 is written by software.
The synchronous trigger (MTU, ELC, or temperature sensor) selected by the ADSTRGR.TRSA[3:0] bits is detected
with ADCSR.EXTRG and ADCSR.TRGE bits being set to 0 and 1, respectively.
A synchronous trigger (MTU or ELC) selected by the ADSTRGR.TRSB[3:0] bits is detected with the
ADCSR.TRGE bit being set to 1 in group scan mode.
The asynchronous trigger is detected with the ADCSR.TRGE and ADCSR.EXTRG bits being set to 1 and the
ADSTRGR.TRSA[3:0] bits being set to "0000b".
[Clearing conditions]
0 is written by software.
The A/D conversion of all the channels selected is completed in single-cycle scan mode.
The A/D conversion of the temperature sensor output or the internal reference voltage selected is completed in
single-cycle scan mode.
Group A scan is completed in group scan mode.
Group B scan is completed in group scan mode.