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Section 23 A/D Converter
23.4.4
Timing of External Trigger Input
A/D conversion can also be started by an externally input trigger signal. Setting the TRGS1 and
TRGS0 bits in ADCR to B'11 selects the signal on the ADTRG pin as an external trigger. The
ADST bit in ADCSR is set to 1 on the falling edge of ADTRG, initiating A/D conversion. Other
operations are the same as those in the case where the ADST bit is set to 1 by software, regardless
of whether the converter is in single mode or scan mode. The timing of this operation is shown in
figure 23.5.
φ
ADTRG
Internal trigger
signal
ADST
Rev. 1.00 Mar. 12, 2008 Page 908 of 1178
REJ09B0403-0100
Figure 23.5 Timing of External Trigger Input
A/D conversion time
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