R01UH0823EJ0100 Rev.1.00 Page 1589 of 1823
Jul 31, 2019
RX23W Group 44. 12-Bit A/D Converter (S12ADE)
44.3.3 Continuous Scan Mode
44.3.3.1 Basic Operation
In basic operation of continuous scan mode, A/D conversion is performed repeatedly on the analog input of the specified
channels as below.
In continuous scan mode, the temperature sensor output A/D conversion select bit (ADEXICR.TSSA) and the internal
reference voltage A/D conversion select bit (ADEXICR.OCSA) should be set to 0 (deselected).
(1) When the ADCSR.ADST bit is set to 1 (A/D conversion start) by software, synchronous trigger, or asynchronous
trigger input, A/D conversion is performed for ANn channels selected by the ADANSA0 and ADANSA1 registers,
starting from the channel with the smallest number n.
(2) 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).
(3) 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).
The 12-bit A/D converter sequentially starts A/D conversion for ANn channels selected by the ADANSA0 and
ADANSA1 registers, starting from the channel with the smallest number n.
(4) The ADCSR.ADST bit is not automatically cleared to 0 and steps 2 and 3 are repeated as long as the bit remains 1
(A/D conversion start). When the ADCSR.ADST bit is set to 0 (A/D conversion stop), A/D conversion stops and
the 12-bit A/D converter enters a wait state.
(5) When the ADST bit is later set to 1 (A/D conversion start), A/D conversion is started again for ANn channels
selected by the ADANSA0 and ADANSA1 registers, starting from the channel with the smallest number n.
Figure 44.9 Example of Operation in Continuous Scan Mode (Basic Operation: AN000 to AN002 Selected)
ADST
A/D conversion
started
Channel 0
(AN000)
Waiting for
conversion
Channel 1
(AN001)
Waiting for conversion
Channel 2
(AN002)
Waiting for conversion
ADDR0
ADDR1
ADDR2
A/D conversion 1
Set
(1)
(2)
Stored
A/D conversion 2
Waiting for conversion
Note 1. indicates the instruction is executed by software.
Note 2. The converted data of A/D conversion 5 is ignored.
Interrupt generated
Waiting for conversion
A/D conversi on 5
*
2
Cleared
(4)
Waiting for conversion
A/D conversion 3
A/D conversion 4
A/D conversion result 1
Waiting for conversion
Waiting for conversion
A/D conversion result 2
A/D conversion result 3
A/D conversion result 4
A/D conversion time
A/D conversion repeated
(2)
(2)
(3)
Set
(5)
A/D conversion 6
(2)
Stored
*
1
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