Hitachi H8/3048 Hardware Manual page 560

16.3 Operation
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The D/A converter has two built-in D/A conversion circuits that can perform conversion
independently.
D/A conversion is performed constantly while enabled in DACR. If the DADR0 or DADR1 value
is modified, conversion of the new data begins immediately. The conversion results are output
when bits DAOE0 and DAOE1 are set to 1.
An example of D/A conversion on channel 0 is given next. Timing is indicated in figure 16-2.
1. Data to be converted is written in DADR0.
2. Bit DAOE0 is set to 1 in DACR. D/A conversion starts and DA
converted result is output after the conversion time. The output value is (DADR0
× V
contents/256)
REF
modified or the DAOE0 bit is cleared to 0.
3. If the DADR0 value is modified, conversion starts immediately, and the result is output after
the conversion time.
4. When the DAOE0 bit is cleared to 0, DA
DADR0
write cycle
ø
Address
bus
DADR0
DAOE0
DA
0
High-impedance state
Legend
t : D/A conversion time
DCONV
Figure 16-2 Example of D/A Converter Operation
. Output of this conversion result continues until the value in DADR0 is
becomes an input pin.
0
DACR
write cycle
Conversion data 1
t
DCONV
550
becomes an output pin. The
0
DADR0
write cycle
Conversion data 2
Conversion
result 2
Conversion
result 1
t
DCONV
DACR
write cycle