Datasheet

Section 19 A/D Converter
Rev. 2.00 Sep. 28, 2009 Page 634 of 870
REJ09B0429-0200
19.4.4 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 19.5.
ADTRG
ADST
A/D conversion time
φ
Internal trigger
signal
Figure 19.5 Timing of External Trigger Input