7721 datasheet(270/577 Pages) RENESAS

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7721 Group User’s Manual

12–19

A-D CONVERTER

12.6 Repeat mode

12.6.2 Repeat mode operation description

(1)

When an internal trigger is selected

The A-D converter starts operation when the A-D conversion start bit is set to “1.”

The first A-D conversion is completed after 57 cycles of

φAD. Then, the contents of the successive

approximation register (conversion result) are transferred to the A-D register i.

The A-D converter repeats operation until the A-D conversion start bit is cleared to “0” by software.

The conversion result is transferred to the A-D register i each time the conversion is completed.

(2)

When an external trigger is selected

____

The A-D converter starts operation when the input level to the ADTRG pin changes from “H” to “L”

while the A-D conversion start bit is “1.”

The first A-D conversion is completed after 57 cycles of

φAD. Then, the contents of the successive

approximation register (conversion result) are transferred to the A-D register i.

The A-D converter repeats operation until the A-D conversion start bit is cleared to “0” by software.

The conversion result is transferred to the A-D register i each time the conversion is completed.

_____

When the level of the ADTRG pin changes from “H” to “L” during operation, the operation at that point

is cancelled and is restarted from step .

Figure 12.6.2 shows the conversion operation in the repeat mode.

Trigger occur

Convert input voltage from

ANi pin

Conversion result

A-D register i

Fig. 12.6.2 Conversion operation in repeat mode

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