HT68F04 Holtek Semiconductor, HT68F04 Datasheet - Page 96

• Manufacturer Part Number: HT68F04
• Description: Small Package Enhanced Flash Type 8-Bit MCU
• Manufacturer: Holtek Semiconductor

A/D Converter Control Registers -
ADCR0, ADCR1, ACERL
To control the function and operation of the A/D con-
verter, three control registers known as ADCR0, ADCR1
and ACERL are provided. These 8-bit registers define
functions such as the selection of which analog channel
is connected to the internal A/D converter, the digitised
data format, the A/D clock source as well as controlling
the start function and monitoring the A/D converter end
of conversion status. The ACS1~ACS0 bits in the
ADCR0 register and ACS4 bit is the ADCR1 register de-
fine the ADC input channel number. As the device con-
tains only one actual analog to digital converter
hardware circuit, each of the individual 4 analog inputs
must be routed to the converter. It is the function of the
ACS4, ACS1 and ACS0 bits to determine which analog
channel input pins or internal 1.25V is actually con-
nected to the internal A/D converter.
Rev. 1.00
A/D Converter Structure
HT66F03/HT66F04/HT68F03/HT68F04
96
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The ACERL control register contains the ACER3~
ACER0 bits which determine which pins on Port A are
used as analog inputs for the A/D converter input and
which pins are not to be used as the A/D converter input.
Setting the corresponding bit high will select the A/D in-
put function, clearing the bit to zero will select either the
I/O or other pin-shared function. When the pin is se-
lected to be an A/D input, its original function whether it
is an I/O or other pin-shared function will be removed. In
addition, any internal pull-high resistors connected to
these pins will be automatically removed if the pin is se-
lected to be an A/D input.
April 16, 2010
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