7721 datasheet(273/577 Pages) RENESAS

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7721 Group User’s Manual

12–22

A-D CONVERTER

12.7.2 Single sweep mode operation description

(1)

When an internal trigger is selected

The operation for the input voltage from the AN0 pin starts when the A-D conversion start bit is

set to “1.”

The A-D conversion of the input voltage from the AN0 pin is completed after 57 cycles of

φAD. Then,

the contents of the successive approximation register (conversion result) are transferred to the

A-D register 0.

For all of the selected analog input pins, the A-D conversion is performed.

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

When step is completed, the A-D conversion interrupt request bit is set to “1.”

The A-D conversion start bit is cleared to “0” and the A-D converter stops operation.

(2)

When an external trigger is selected

The A-D converter starts operation for the input voltage from the AN0 pin when the input level to

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the ADTRG pin changes from “H” to “L” while the A-D conversion start bit is “1.”

The A-D conversion of the input voltage from the AN0 pin is completed after 57 cycles of

φAD. Then,

the contents of the successive approximation register (conversion result) are transferred to the

A-D register 0.

For all of the selected analog input pins, the A-D conversion is performed.

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

When step is completed, the A-D conversion interrupt request bit is set to “1.”

The A-D conversion stops.

The A-D conversion start bit remains set to “1” after the operation is completed. Accordingly, the

_____

operation of the A-D converter can be performed again from step when the level of the ADTRG pin

changes from “H” to “L.”

_____

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 12.7.2 shows the conversion operation in the single sweep mode.

12.7 Single sweep mode

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