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Rev. 1.00
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Standard 8051 8-Bit Flash MCU
HT85F2260/HT85F2270/HT85F2280
Analog to Digital Converter –
ADC
Digital to
Analog Converter – DAC
31
Digital to Analog Converter – DAC
All devices include a Digital to Analog Converter permitting the conversion of a 12-bit digital
value into an analog voltage. An additional programmable attenuation control function provides
further flexibility over the overall input/output transfer function.
DAC Register Description
A pair of data register, DAL and DAH, store the 12-bit digital value which is to be converted, while
an additional control register, DACTRL, controls the attenuation level, reference voltage select and
enable/disable control.
DAH Register
SFR Address: B5h
Bit
7
6
5
4
3
2
1
0
Name
D11
D10
D9
D8
D7
D6
D�
D4
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
1
0
0
0
0
0
0
0
Bit 7~0
D11~D4:
DAC output data bit 11~4
DAL Register
SFR Address: B4h
Bit
7
6
5
4
3
2
1
0
Name
D3
D�
D1
D0
—
—
—
—
R/W
R/W
R/W
R/W
R/W
—
—
—
—
POR
0
0
0
0
—
—
—
—
Bit 7~4
D3~D0:
DAC output data bit 3~0
Bit 3~0
Unimplemented, read as “0”
DACTRL Register
SFR Address: B3h
Bit
7
6
5
4
3
2
1
0
Name
VOL�
VOL1
VOL0
—
—
—
VREFDS
DACEN
R/W
R/W
R/W
R/W
—
—
—
R/W
R/W
POR
0
0
0
—
—
—
0
0
Bit 7~5
VOL2~VOL0:
DAC attenuation control
There are 8 levels of DAC attenuation selected using these three bits. The accompanying
table illustrates the relationship between the DAC attenuation control bits and the DAC
data output.