R01UH0823EJ0100 Rev.1.00
Page 1586 of 1823
Jul 31, 2019
RX23W Group
44. 12-Bit A/D Converter (S12ADE)
44.3.2.2
Channel Selection and Self-Diagnosis
When channels and self-diagnosis are selected, A/D conversion is performed once for the reference voltage VREFH0
supplied to the 12-bit A/D converter as below. After that, A/D conversion is performed only once on the analog input of
the selected channels.
(1) A/D conversion for self-diagnosis is started when the ADCSR.ADST bit is set to 1 (A/D conversion start) by
software, synchronous trigger, or asynchronous trigger input.
(2) When A/D conversion for self-diagnosis is completed, A/D conversion result is stored into the A/D self-diagnosis
data register (ADRD), and A/D conversion is performed for ANn channels selected by the ADANSA0 and
ADANSA1 registers, starting from the channel with the smallest number n.
(3) Each time A/D conversion of a single channel is completed, the A/D conversion result is stored into the
corresponding A/D data register (ADDRy).
(4) When A/D conversion of all the selected channels is completed, an S12ADI0 interrupt request is generated if the
ADCSR.ADIE bit is 1 (S12ADI0 interrupt upon scanning completion enabled).
(5) The ADST bit remains 1 (A/D conversion start) during A/D conversion, and is automatically cleared to 0 when A/D
conversion of all the selected channels is completed. Then the 12-bit A/D converter enters a wait state.
Figure 44.6
Example of Operation in Single Scan Mode (Basic Operation: AN000, AN007 Se Self-
Diagnosis)
ADST
A/D conversion
started
Reference
voltage
(x0, x½, x1)
Waiting for conversion
Channel 0
(AN000) Waiting for conversion
Waiting for conversion
ADRD
ADDR0
A/D conversion for
self-diagnosis
Set
*1
(1)
(2)
Waiting for conversion
A/D conversion for self-diagnosis result 1
Waiting for conversion
A/D conversion result 1
A/D conversion result 2
A/D conversion time
Scanning performed once
(3)
(3)
(4)
(5)
Waiting for conversion
A/D conversion 1
A/D conversion 2
Stored
Stored
Note 1.
indicates the instruction is executed by software.
Stored
Interrupt generated
S12ADI0
ADDR7
Channel 7
(AN007)