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CHAPTER 14 A/D CONVERTER
(6) Interrupt request flag (ADIF)
The interrupt request flag (ADIF) is not cleared even if the A/D converter mode register (ADM) is changed.
If an analog input pin is changed during A/D conversion, the A/D conversion result and ADIF for the pre-change
analog input may have been set immediately before the ADM rewrite. In this case, if ADIF is read immediately
after the ADM rewrite, ADIF may be set despite the fact that the A/D conversion for the post-change analog
input has not ended.
When the A/D conversion is stopped and then resumed, clear the ADIF before it is resumed.
Figure 14-12. A/D Conversion End Interrupt Request Generation Timing
(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 same voltage as VDD to this pin even when the application circuit is designed
so as to switch to a backup battery as shown in Figure 14-13.
Figure 14-13. Handling of AV
DD Pin
A/D Conversion
ADCR
INTAD
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
Main
power
supply
AV
REF0
V
DD
AV
DD
AV
SS
V
SS
Capacitor
for back-up