Channel Selection And Self-Diagnosis (With Channel-Dedicated Sample-And-Hold Circuits) - Renesas RX100 Series User Manual

RX13T Group
26.3.3.4 Channel Selection and Self-Diagnosis (With Channel-Dedicated Sample-and-
Hold Circuits)
When channels and self-diagnosis are selected and a channel-dedicated sample-and-hold circuit is used, sample-and-hold
operations are performed first, and A/D conversion is performed for the reference voltage supplied to the 12-bit A/D
converter as below. After that, A/D conversion is performed repeatedly on the analog input of the selected channels.In
continuous scan mode, the internal reference voltage A/D conversion select bit (S12AD.ADEXICR.OCSA) should be set
to 0 (deselected).
(1) Analog input sampling of all channels for which the channel-dedicated sample-and-hold circuits are to be used is
started when the ADCSR.ADST bit is set to 1 (A/D conversion start) by software, or synchronous or asynchronous
trigger input.
(2) A/D conversion for self-diagnosis is started after completion of sampling and holding.
(3) 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 register,
starting from the channel with the smallest number n.
(4) 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).
(5) 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 upon scanning completion enabled). At the same time, analog input sampling is
started for all the channels for which the channel-dedicated sample-and-hold circuits are to be used.
(6) The ADCSR.ADST bit is not automatically cleared and steps 2 to 5 are repeated as long as the ADCSR.ADST bit
remains 1. When the 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.
(7) When the ADST bit is later set to 1 (A/D conversion start), the A/D conversion for self-diagnosis is started again.
A/D conversion
ADST
started
Reference voltage
Waiting for conversion
(×0, ×½, ×1)
Channel 0
Waiting for conversion
(AN000)
Channel 1
Waiting for conversion
(AN001)
ADRD
ADDR0
ADDR1
Scan end
interrupt
Note 1. indicates the instruction is executed by software.
Figure 26.12 Example of Operation in Continuous Scan Mode
(Channel-Dedicated Sample-and-Hold Circuits Used: AN000 and AN001 Selected + Self-
Diagnosis)
R01UH0822EJ0100 Rev.1.00
Jul 31, 2019
Sampling-and-holding,
Set *1
(1)
A/D conversion
Sample-and-hold time time
A/D conversion for
self-diagnosis 1
(2)
Sampling Holding
A/D conversion 1
Sampling Holding
(3)
Stored
A/D conversion for self-diagnosis result 1
self-diagnosis and scanning performed repeatedly
Waiting for conversion
Waiting for
Sampling
conversion
Sampling
A/D conversion 2
Stored (4)
A/D conversion for self-diagnosis result 1
Stored (4)
A/D conversion result 2
(5)
Interrupt generated
26. 12-Bit A/D Converter (S12ADF)
Clear Set
(7)
(6)
A/D conversion for
self-diagnosis 2
Waiting for
Holding Sampling
conversion
Waiting for
Sampling
Holding
conversion
A/D conversion for self-diagnosis result 2
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