Analog To Digital Converter - Holtek HT66F20-1 Manual

HT66F20-1/HT66F30-1/HT68F20-1/HT68F30-1
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. The
A/D Converter is only contained in the HT66F30-1 and HT66F20-1 devices.
A/D Overview
The HT66F30-1 contains a multi-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 either a 12-bit digital value.
Part No.
HT��F�0-1/HT��F�0-1
The accompanying block diagram shows the overall internal structure of the A/D converter, together
with its associated registers.
A C E 7 ~ A C E 0
P A 0 / A N 0 ~ P A 7 / A N 7
V 1 2 5 E N
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
ADRL(ADRFS=0)
ADRL(ADRFS=1)
ADRH(ADRFS=0)
ADRH(ADRFS=1)
ADCR0
ADCR1
ACERL
Rev. 1.40
Input Channels
8
A D C K 2 ~ A D C K 0
A / D C l o c k
1 . 2 5 V
A C S 4 , A C S 2 ~ A C S 0
A/D Converter Structure
7 6 5
D� D� D1
D7 D� D5
D11 D10 D9
— — —
START EOCB ADOFF
ACS4 V1�5E� —
ACE7 ACE� ACE5
A/D Converter Register List – HT66F30-1/HT66F20-1
1�1
A/D Channel Select Bits
ACS4� ACS�~ACS0
V
D D
f
S Y S
N
¸ 2
P B 5 / V R E F
( N = 0 ~ 6 )
A D O F F
B i t
V R E F S
B i t
A / D R e f e r e n c e V o l t a g e
A / D C o n v e r t e r
V
S S
S T A R T E O C B A D O F F
Bit
4 3 2
D0 — —
D4 D� D�
D8 D7 D�
— D11 D10
ADRFS — ACS�
VREFS — ADCK�
ACE4 ACE� ACE�
�ove��e� ��� �01�
Input Pins
A�0~A�7
A D R L
A / D D a t a
R e g i s t e r s
A D R H
A D R F S
b i t
1 0
— —
D1 D0
D5 D4
D9 D8
ACS1 ACS0
ADCK1 ADCK0
ACE1 ACE0