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CHAPTER 11 A/D CONVERTER
User
’
s Manual U15017EJ2V0UD
11.4.3 Operation mode of A/D converter
Select one analog input channel from ANI0 to ANI11 by the A/D converter input select register (ADIS) to start A/
D conversion.
The A/D conversion operation can be started only by software (by setting the A/D converter mode register (ADM)).
The A/D conversion result is stored in the A/D conversion result register (ADCR), and an interrupt request signal
(INTAD) is generated.
A/D conversion by software start
Converting the voltage applied to the analog input pin specified by the A/D converter input select register (ADIS)
is started when bit 7 (ADCS) of the A/D converter mode register (ADM) is set to 1.
When the A/D conversion has been completed, the result of the conversion is stored in the A/D conversion result
register (ADCR), and an interrupt request (INTAD) is generated. When the A/D conversion has been started
and completed once, the next conversion operation is immediately started. This is repeated until new data is
written to ADIS.
If ADIS is rewritten during A/D conversion, the conversion under execution is stopped, and conversion of the
selected analog input channel is started.
If data with ADCS being 0 is written to the ADM during A/D conversion, the conversion is immediately stopped.
Figure 11-6. A/D Conversion by Software Start
Remark
n = 0, 1, ... 11
m = 0, 1, ... 11
Caution The first A/D conversion result obtained immediately after setting bit 7 (ADCS) of the A/D
converter mode register (ADM) to 1 is undefined and should be discarded by polling the A/D
conversion end interrupt request (INTAD).
Rewriting ADIS
ADCS = 1
Rewriting ADIS
ADCS = 1
ADCS = 0
A/D conversion
ADCR
INTAD
ANIn
ANIn
ANIn
ANIm
ANIm
Stop
Undefined value
ANIn
Undefined value
Conversion result
does not remain
during A/D conversion