SH7280 Datasheet, PDF (1031/1726 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine family

Section 20 A/D Converter (ADC)
20.4.5 External Trigger Input Timing
The A/D conversion can also be externally triggered. To input an external trigger, set the pin
function controller (PFC) to select the ADTRG pin function, drive the ADTRG pin high, set the
TRGE bit to 1 in ADCR, clear the ADST bit to 0, and set the EXTRG bit to 1. In this state, input a
trigger through the ADTRG pin. A falling edge of the ADTRG signal sets the ADST bit to 1 in
ADCR, starting the A/D conversion. Other operations are conducted in the same way as when A/D
conversion is activated by writing 1 to the ADST bit by software. Figure 20.11 shows the timing.
The ADST bit is set to 1 after ((5 – n*)Pφ) states have elapsed from the point at which the A/D
converter detects a falling edge on the ADTRG pin.
Notes: *
n=0 when Pφ : Aφ = 1:1
n=1 when Pφ : Aφ = 1:2
n=2 when Pφ : Aφ = 1:4
Pφ
ADTRG
External trigger
signal
ADST
A/D conversion
Figure 20.11 External Trigger Input Timing
Rev. 1.00 Jun. 26, 2008 Page 1001 of 1692
REJ09B0393-0100