Datasheet

Section 19 D/A Converter
Rev. 4.00 Sep 27, 2006 page 611 of 1130
REJ09B0327-0400
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
φ
DADR0
DAOE0
DA0
Conversion data (1) Conversion data (2)
High-impedance state
Conversion result (1)
Conversion result (2)
t
DCONV
t
DCONV
t : D/A conversion time
Legend:
DCONV
Figure 19.2 D/A Conversion (Example)