R01UH0822EJ0100 Rev.1.00
Page 808 of 1041
Jul 31, 2019
RX13T Group
26. 12-Bit A/D Converter (S12ADF)
Table 26.1
Specifications of 12-Bit A/D Converter (1/2)
Item
Description
Number of units
One unit (S12AD)
Input channels
Eight channels for S12AD
Extended analog function
Internal reference voltage
A/D conversion method
Successive approximation method
Resolution
12 bits
Conversion time
1.4 μs per channel
(when A/D conversion clock ADCLK = 32 MHz)
A/D conversion clock
Peripheral module clock PCLK*
and A/D conversion clock ADCLK*
can be set so that the frequency ratio
should be one of the following.
PCLK to ADCLK frequency ratio = 1:1, 2:1, 4:1, 8:1
ADCLK is set using the clock generation circuit.
Data registers
Eight registers for analog input, 1 for A/D-converted data duplication in double trigger mode, and 2 for A/
D-converted data duplication during extended operation in double trigger mode.
One register for internal reference
One register for self-diagnosis
The results of A/D conversion are stored in 12-bit A/D data registers.
12-bit accuracy output for the results of A/D conversion
The value obtained by adding up A/D-converted results is stored as a value in the number of bit for
conversion ac 2 bits/4 bits*
in the A/D data registers in A/D-converted value addition mode.
Double trigger mode (selectable in single scan and group scan modes):
The first piece of A/D-converted analog-input data on one selected channel is stored in the data register
for the channel, and the second piece is stored in the duplication register.
Extended operation in double trigger mode (available for specific triggers):
A/D-converted analog-input data on one selected channel is stored in the duplication register that is
prepared for each type of trigger.
Operating modes
Single scan mode:
A/D conversion is performed only once on the analog inputs arbitrarily selected.
A/D conversion is performed only once on the internal reference voltage.
Continuous scan mode:
A/D conversion is performed repeatedly on the analog inputs arbitrarily selected.
Group scan mode:
Two (groups A and B) or three (groups A, B, and C) can be selected as the number of the groups to be
used.
Only the combination of groups A and B can be selected when the number of the groups is two.
Analog inputs arbitrarily selected are divided into two groups (group A and B) or three groups (group A,
B, and C), and A/D conversion of the analog input selected on a group basis is performed only once.
The conditions for scanning start of groups A, B, and C (synchronous trigger) can be independently
selected, thus allowing A/D conversion of each group to be started independently.
Group scan mode (when group priority control selected):
If a priority-group trigger is input during scanning of the low-priority group, scan of the low-priority group
is stopped and scan of the priority group is started. The priority order is group A (highest) > group B >
group C (lowest).
Whether or not to restart scanning of the low-priority group after processing for the high-priority group
completes, is selectable. Rescan can also be set to start either from the beginning of the selected
channel or the channel on which A/D conversion is not completed.
Conditions for A/D
conversion start
Software trigger
Synchronous trigger
Trigger by the multi-function timer pulse unit (MTU)
Asynchronous trigger
A/D conversion can be triggered by the external trigger ADTRG0# pin.
Functions
Channel-dedicated sample-and-hold function (three channels)
Input signal amplification function of the programmable gain amplifier (3 channels)
Variable sampling state count (settable for each channel)
Self-diagnosis of 12-bit A/D converter
Selectable A/D-converted value addition mode or average mode
Analog input disconnection detection assist function (discharge function/precharge function)
Double trigger mode (duplication of A/D conversion data)
Automatic clear function of A/D data registers