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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
ADCR0 Register
SFR Address: F1h
Bit
7
6
5
4
3
2
1
0
Name
START
EOCB
ADOFF
ADRFS
ACS3
ACS�
ACS1
ACS0
R/W
R/W
R
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
1
1
0
0
0
0
0
Bit 7
START:
Starts the A/D conversion
0
→
1
→
0: Start
0
→
1: Reset the A/D converter and set EOCB to “1”
This bit is used to initiate an A/D conversion process. The bit is normally low but if set
high and then cleared low again, the A/D converter will initiate a conversion process.
When the bit is set high the A/D converter will be reset.
Bit 6
EOCB:
End of A/D conversion flag
0: A/D conversion ended
1: A/D conversion in progress
This read only flag is used to indicate when an A/D conversion process has completed.
When the conversion process is running the bit will be high.
Bit 5
ADOFF
: ADC power on/off control bit
0: ADC power on
1: ADC power off
This bit controls the power to the A/D internal function. This bit should be cleared
to zero to enable the A/D converter. If the bit is set high then the A/D converter will
be switched off reducing the device power consumption. As the A/D converter will
consume a limited amount of power, even when not executing a conversion, this may be
an important consideration in power sensitive battery powered applications.
Bit 4
ADRFS:
ADC Data Format Control
0: ADC Data MSB is ADRH bit 7, LSB is ADRL bit 4
1: ADC Data MSB is ADRH bit 3, LSB is ADRL bit 0
This bit controls the format of the 12-bit converted A/D value in the two A/D data
registers.
Bit 3~0
ACS3~ACS0:
Select A/D channel (when ACS4 is “0”)
0000: AIN.0
0001: AIN.1
0010: AIN.2
0011: AIN.3
0100: AIN.4
0101: AIN.5
0110: AIN.6
0111: AIN.7
1xxx: Undefined, must not be used
These are the A/D channel select control bits. As there is only one internal hardware
A/D converter each of the eight A/D inputs must be routed to the internal converter
using these bits. If bit ACS4 in the ADCR1 register is set high then the internal
temperature sensor will be routed to the A/D Converter and these ADC input channels
disconnected.