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CHAPTER 12 10-BIT A/D CONVERTER (
µ
PD780034AS SUBSERIES)
Preliminary User’s Manual U16035EJ1V0UM
Normal conversion result
Undefined value
A/D conversion completes
A/D conversion completes
Normal conversion result is read.
A/D conversion
is stopped.
Undefined value
is read.
ADCR0
INTAD0
ADCS0
Normal conversion result
A/D conversion completes
Normal conversion
result is read.
A/D conversion is stopped.
ADCR0
INTAD0
ADCS0
(10) Timing at which A/D conversion result is undefined
The A/D conversion value may be undefined if the timing of completion of A/D conversion and the timing of
stopping the A/D conversion conflict with each other. Therefore, read the A/D conversion result during the A/
D conversion operation. To read the conversion result after stopping the A/D conversion operation, be sure to
stop the A/D conversion before the next conversion ends.
Figures 12-18 and 12-19 show the timing of reading the conversion result.
Figure 12-18. Timing of Reading Conversion Result (When Conversion Result Is Undefined)
Figure 12-19. Timing of Reading Conversion Result (When Conversion Result Is Normal)
(11) Notes on board design
Locate analog circuits as far away from digital circuits as possible on the board because the analog circuits may
be affected by the noise of the digital circuits. In particular, do not cross an analog signal line with a digital signal
line, or wire an analog signal line in the vicinity of a digital signal line. Otherwise, the A/D conversion
characteristics may be affected by the noise of the digital line.
Connect AV
SS0
and V
SS0
at one location on the board where the voltages are stable.
