7721 datasheet(277/577 Pages) RENESAS

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7721 Group User’s Manual

12–26

A-D CONVERTER

12.8.2 Repeat 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.

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

The operation is performed repeatedly until the A-D conversion start bit is cleared to “0” by

software.

(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

______

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.

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

The operation is performed repeatedly until the A-D conversion start bit is cleared to “0” by

software.

______

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 12.8.2 shows the conversion operation in the repeat sweep mode.

12.8 Repeat sweep mode

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