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Rev. 1.21
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HT66F488/HT66F489
A/D Flash MCU with EEPROM
HT66F488/HT66F489
A/D Flash MCU with EEPROM
Analog to Digital Converter
The need to interface to real world analog signals is a common requirement for many electronic
systems. However, to properly process these signals by a microcontroller, they must first be
converted into digital signals by A/D converters. By integrating the A/D conversion electronic
circuitry into the microcontroller, the need for external components is reduced significantly with the
corresponding follow-on benefits of lower costs and reduced component space requirements.
A/D Overview
The device contains a 8-channel analog to digital converter which can directly interface to external
analog signals, such as that from sensors or other control signals and convert these signals directly
into a 12-bit digital value.
The accompanying block diagram shows the overall internal structure of the A/D converter, together
with its associated registers.
A/D Converter Structure
A/D Converter Register Description
Overall operation of the A/D converter is controlled using five registers. A read only register pair
exists to store the ADC data 12-bit value. The remaining three registers are control registers which
setup the operating and control function of the A/D converter.
Register
Name
Bit
7
6
5
4
3
2
1
0
ADRL(ADRFS=�)
D3
D2
D1
D�
—
—
—
—
ADRH(ADRFS=�)
D11
D1�
D�
D8
D�
D6
D5
D4
ADRL(ADRFS=1)
D�
D6
D5
D4
D3
D2
D1
D�
ADRH(ADRFS=1)
—
—
—
—
D11
D1�
D�
D8
ADCR�
START
EOCB
ADOFF ADRFS
—
ACS2
ACS1
ACS�
ADCR1
ACS4 V125E�
—
VREFS1 VREFS� ADCK2 ADCK1 ADCK�
ACERL
ACE�
ACE6
ACE5
ACE4
ACE3
ACE2
ACE1
ACE�
A/D Converter Register List