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CHAPTER 12 A/D CONVERTER
User’s Manual U19780EJ2V0UD
344
(3) Timer trigger mode (continuously convert mode)
<1>
Timer trigger mode is specified by setting bit 7 (ADTMD) of A/D converter mode register 1 (ADM1) to 1, after
which the A/D converter waits for a timer trigger.
<2>
When the timer trigger signal is detected, bit 7 (ADCS) of the A/D converter mode register (ADM) is
automatically set to 1 and A/D conversion of the voltage applied to the analog input pin specified using the
analog input channel specification register (ADS) starts.
<3>
When A/D conversion has been completed, the result of the A/D conversion is stored in the A/D conversion
result register (ADCR, ADCRH), and an interrupt request signal (INTAD) is generated. When one A/D
conversion has been completed, the next A/D conversion operation is immediately started. .
<4>
If ADS is rewritten during A/D conversion, the A/D conversion operation under execution is stopped and
restarted from the beginning. At this time, the conversion result immediately before is retained.
<5>
If a timer trigger signal is generated during A/D conversion, the A/D conversion operation under execution is
stopped and restarted from the beginning. At this time, the conversion result immediately before is retained.
<6>
If 0 is written to ADCS during A/D conversion, A/D conversion immediately stops and the A/D converter waits
for a timer trigger. At this time, the conversion result immediately before is retained.
<7>
When 0 is written to ADTMD while A/D conversion operation is stopped (ADCS = 0), the software trigger
mode is set and A/D conversion operation is not started, even if a timer trigger signal is generated.
Figure 12-17. Timer Trigger Mode (continuously convert mode)
ANIn
ANIn
ANIn
ANIm
ANIn
ANIm
ANIm
ADCR,
ADCRH
INTAD
ADCS
ANIm
ANIn
ADTMD
<2> Timer trigger generate
Timer trigger
<5> Timer trigger generate
Note
standby
state
standby
state
Conversion is stopped
Conversion starts from
beginning
Conversion is stopped
Conversion starts from
beginning
Stopped
<3> A/D conversion
end
<3> A/D conversion
end
<3> A/D conversion
end <4> Rewriting ADS
A/D conversion
<1>
ADTMD
=
1
<7>
ADTMD
=
1
<6>
ADCS
=
0
Note
Make sure that the timer trigger signal is generated at intervals equal to or longer than the A/D conversion
time.
Remark
78K0/KB2-A: n = 0 to 5, 8 to 11, m = 0 to 5, 8 to 11
78K0/KC2-A: n = 0 to 6, 8 to 11, 15, m = 0 to 6, 8 to 11, 15