R01UH0822EJ0100 Rev.1.00
Page 847 of 1041
Jul 31, 2019
RX13T Group
26. 12-Bit A/D Converter (S12ADF)
26.3.3
Continuous Scan Mode
26.3.3.1
Basic Operation (Without Channel-Dedicated Sample and-Hold Circuits)
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 internal reference voltage A/D conversion select bit (S12AD.ADEXICR.OCSA) should be
set to 0 (deselected).
(1) When the ADCSR.ADST bit is set to 1 (A/D conversion start) by software, or synchronous or asynchronous trigger
input, A/D conversion is performed for ANn channels selected by the ADANSA0 register, 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, a scan end interrupt request is generated if the
ADCSR.ADIE bit is 1 (interrupt generation upon scanning completion enabled).
The 12-bit A/D converter sequentially starts A/D conversion for ANn channels selected by the ADANSA0 register,
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 register, starting from the channel with the smallest number n.
Figure 26.9
Example of Operation in Continuous Scan Mode (Basic Operation: AN000 to AN002 Selected)
ADST
A/D conversion
started
Waiting for
conversion
Waiting for conversion
Waiting for conversion
ADDR0
ADDR1
ADDR2
A/D conversion 1
Set*
1
(1)
A/D conversion 2
Waiting for conversion
Interrupt generated
Waiting for conversion
A/D conversion 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
Note 1. indicates the instruction is executed by software.
Note 2. The converted data of A/D conversion 5 is ignored.
(2)
Stored
(2)
Scan end
interrupt
Channel 0
(AN000)
Channel 1
(AN001)
Channel 2
(AN002)
Stored