HT46801N-1 Holtek Semiconductor, HT46801N-1 Datasheet - Page 43

• Manufacturer Part Number: HT46801N-1
• Description: (HT4xR01x-1) Small Package 8-Bit OTP MCU
• Manufacturer: Holtek Semiconductor

www.DataSheet.co.kr
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 con-
version 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 HT46R01B-1 and HT46R01N-1 devices contain a
4-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 sig-
nals directly into either a 12-bit digital value.
The accompanying block diagram shows the overall in-
ternal structure of the A/D converter, together with its as-
sociated registers.
A/D Converter Data Registers - ADRL, ADRH
The device, which has an internal 12-bit A/D converter,
requires two data registers, a high byte register, known
as ADRH, and a low byte register, known as ADRL. After
the conversion process takes place, these registers can
be directly read by the microcontroller to obtain the digit-
ised conversion value. Only the high byte register,
ADRH, utilises its full 8-bit contents. The low byte regis-
ter utilises only 4 bit of its 8-bit contents as it contains
only the lowest bits of the 12-bit converted value.
In the following table, D0~D11 is the A/D conversion
data result bits.
Rev.1.00
A/D Converter Structure
43
A/D Converter Control Registers - ADCR, ACSR
To control the function and operation of the A/D con-
verter, two control registers known as ADCR and ACSR
are provided. These 8-bit registers define functions
such as the on/off function, selection of which analog
channel is connected to the internal A/D converter,
which pins are used as analog inputs and which are
used as normal I/Os, the A/D clock source as well as
controlling the start function and monitoring the A/D con-
verter end of conversion status.
The ACS1~ACS0 bits in the ADCR register define the
channel number. As the device contains only one actual
analog to digital converter circuit, each of the individual
4 analog inputs must be routed to the converter. It is the
function of the ACS1~ACS0 bits in the ADCR register to
determine which analog channel is actually connected
to the internal A/D converter.
The PCR3~PCR0 bits contained in the ADCR register
which determine which pins on PA0~PA3 are used as
analog inputs for the A/D converter and which pins are
to be used as normal I/O pins. If the PCRn bit has a
value of 1, then the corresponding pin, namely one of
the AN0~AN3 analog inputs, will be set as analog in-
puts. Note that if the PCRn bit is set to zero, then the cor-
responding pin on PA0~PA3 will be setup as a normal
I/O pin, the analog input channels will be all disabled
and the A/D converter circuitry will be powered off.
Register
ADRH
ADRL
D11 D10 D9
Bit
D3
7
A/D Data Registers
HT46R01B-1/HT46R01N-1
HT48R01B-1/HT48R01N-1
Bit
D2
6
Bit
D1
5
Bit
D0
D8
4
Bit
D7
3
Bit
D6
2
June 9, 2011
Bit
D5
1
Bit
D4
0
Datasheet pdf - http://www.DataSheet4U.net/