HD64F2149YV datasheet(687/1075 Pages) RENESAS

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Section 19 D/A Converter

Rev. 3.00 Jan 18, 2006 page 659 of 1044

REJ09B0280-0300

19.3

Operation

The D/A converter module has two built-in D/A converter circuits that can operate independently.

D/A conversion is performed continuously whenever enabled by the D/A control register (DACR).

When a new value is written in DADR0 or DADR1, conversion of the new value begins

immediately. The converted result is output by setting the DAOE0 or DAOE1 bit to 1.

An example of conversion on channel 0 is given next. Figure 19.2 shows the timing.

• Software writes the data to be converted in DADR0.

• D/A conversion begins when the DAOE0 bit in DACR is set to 1. After the elapse of the

conversion time, analog output appears at the DA0 pin. The output value is AVref

× (DADR

value)/256.

• This output continues until a new value is written in DADR0 or the DAOE0 bit is cleared to 0.

• If a new value is written in DADR0, conversion begins immediately. Output of the converted

result begins after the conversion time.

• When the DAOE0 bit is cleared to 0, DA0 becomes an input pin.

DADR0

write cycle

DACR

write cycle

DADR0

write cycle

DACR

write cycle

Address

DADR0

DAOE0

DA0

Conversion data (1)

Conversion data (2)

High-impedance state

Conversion result (1)

Conversion result (2)

t DCONV

D/A conversion time

DCONV

Figure 19.2 D/A Conversion (Example)

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