CHAPTER 12 A/D CONVERTER
204
User’s Manual U11302EJ4V0UM
(6) Interrupt request flag (ADIF)
The interrupt request flag (ADIF) is not cleared even if the A/D converter mode register (ADM) is changed.
Therefore, if an analog input pin is changed during A/D conversion, the A/D conversion result for the
analog input before changing and ADIF may be set immediately before rewriting ADM. In this case, if
ADIF is read immediately after the rewriting of ADM, ADIF is set despite the fact that A/D conversion of
the analog input after changing has not been completed (refer to
Figure 12-10
).
When A/D conversion is stopped, ADIF must be cleared before restarting.
Figure 12-10. A/D Conversion End Interrupt Request Generation Timing
Remark
n = 0, 1, ... , 7
m = 0, 1, ... , 7
(7) AV
DD
pin
The AV
DD
pin is the analog circuit power supply pin, and supplies power to the input circuits of ANI0/P10
to ANI7/P17.
Therefore, be sure to apply the voltage at the same level as V
DD
as shown in Figure 12-11 even in an
application where the power supply is switched to the back-up power supply.
Figure 12-11. AV
DD
Pin Connection
ADCR
INTAD
A/D conversion
ANIn
ANIn
ANIm
ANIm
ANIn
ANIn
ANIm
ANIm
ADM rewrite
(start of ANIn conversion)
ADM rewrite
(start of ANIm conversion)
ADIF is set but ANIm
conversion has not ended
AV
REF
Back up
capacitor
Main power supply
V
DD
AV
DD
V
SS
AV
SS
Содержание mPD780204
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