R01UH0823EJ0100 Rev.1.00
Page 1624 of 1823
Jul 31, 2019
RX23W Group
45. 12-Bit D/A Converter (R12DAA)
45.2.5
D/A VREF Control Register (DAVREFCR)
The DAVREFCR register selects the reference voltage of the 12-bit D/A converter.
REF[2:0] Bits (D/A Reference Voltage Select)
The REF[2:0] bits select the reference voltage of the 12-bit D/A converter 0 and 1. When changing the value of these
bits, write 000b to the DAVREFCR.REF[2:0] bits in advance. Read the REF[2:0] bits after changing their value, and
confirm that it has been changed. When selecting the internal reference voltage, set the DADR0 and DADR1 registers to
0000h and discharge the VREF path before switching the voltage. As the path remains discharged after the reset is
released, the internal reference voltage can be selected. For details on discharging, refer to
Using the Internal Reference Voltage as the Reference Voltage
. Do not rewrite this register during A/D conversion
using the 12-bit A/D converter. If this register is rewritten, the accuracy of A/D conversion is not guaranteed.
When the internal reference voltage is selected, the voltage generation circuit operates and current increases by about
75 μA. This circuit is not automatically turned off even if the MCU enters software standby mode with the internal
reference voltage selected.
Address(es): DA.DAVREFCR 0008 8047h
b7
b6
b5
b4
b3
b2
b1
b0
—
—
—
—
—
REF[2:0]
Value after reset:
0
0
0
0
0
0
0
0
Bit
Symbol
Bit Name
Description
R/W
b2 to b0
D/A Reference Voltage Select
b2
b0
0 0 0: Not selected
0 0 1: AVCC0/AVSS0
0 1 1: Internal reference voltage/AVSS0
Settings other than above are prohibited.
R/W
b7 to b3
—
Reserved
These bits are read as 0. The write value should be 0.
R/W