RL78/F13, F14 CHAPTER 13 D/A CONVERTER (RL78/F14 Only)
R01UH0368EJ0210 Rev.2.10 775
Dec 10, 2015
13.5 Cautions for D/A Converter
Observe the following cautions when using the D/A converter.
(1) The digital port I/O function, which is the alternate function of the ANO0 pin, does not operate if the ports are set to
analog pins by using the A/D port configuration register (ADPC). When the P8 register is read while the ports are
set to analog pins by using the ADPC register, 0 is read in the input mode and the set value of the P8 register is
read in the output mode. If the digital output mode is set, no data is output to the pins.
(2) The operation of the D/A converter continues in the HALT and STOP modes. To lower the power consumption,
therefore, clear the DACE0 bit to 0, and execute the HALT or STOP instruction after stopping the operation of the
D/A converter.
(3) To stop the real-time output mode (including when changing to normal mode), one of the following procedures must
be used:
• Wait for at least three clocks after stopping the trigger output source and then set bits DACE0 and DAMD0 to 0.
• After setting bits DACE0 and DAMD0, set the DACEN bit of the PER1 register to 0 (DAC stop).
• When the DACEN bit is set to 0, all the registers in the DAC are cleared, so the settings of the SFRs are
required to start the operation again.
(4) When D/A conversion operation is enabled, do not perform A/D conversions from the analog input pin multiplexed
with the ANO0 pin.
(5) In the real-time output mode, set the value of the DACS0 register before a timer trigger is generated. Do not change
the set value of the DACS0 register while the trigger signal is output.
(6) Since the output impedance of the D/A converter is high, no current can be taken out from the ANO0 pin. If the input
impedance of the load is low, insert a follower amplifier between the load and the ANO0 pin before use. In addition,
the wiring length between the follower amplifier and the load must be as short as possible due to the high output
impedance. If the wiring length is long, take measures such as placing a ground pattern around the wiring area.
(7) When entering the STOP state while the real-time output mode for D/A conversion is enabled, disable linking of
ELC events before entering STOP.
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