NEC PD703114 User Manual page 542

11.11.6 Timing that makes the A/D conversion result undefined
If the timing of the end of A/D conversion and the timing of the stop of operation of the A/D converter conflict, the
A/D conversion value may be undefined. Because of this, be sure to read the A/D conversion result while the A/D
converter is in operation. Furthermore, when reading an A/D conversion result after the A/D converter operation has
stopped, be sure to have done so by the time the next conversion result is complete.
The conversion result read timing is shown in Figures 11-14 and 11-15 below.
Figure 11-14. Conversion Result Read Timing (When Conversion Result Is Undefined)
ADCRnm
INTADn
ADCEn
Remark n = 0, 1
When n = 0: m = 0 to 5
When n = 1: m = 0 to 7
Figure 11-15. Conversion Result Read Timing (When Conversion Result Is Normal)
ADCRnm
INTADn
ADCEn
Remark n = 0, 1
When n = 0: m = 0 to 5
When n = 1: m = 0 to 7
542
CHAPTER 11 A/D CONVERTER
A/D conversion end
Normal conversion result
Normal conversion
result read
A/D conversion end
A/D operation stopped
User's Manual U15195EJ5V0UD
A/D conversion end
Undefined value
A/D operation
stopped
Normal conversion result
Normal conversion
result read
Undefined
value read