AN1740 Freescale Semiconductor / Motorola, AN1740 Datasheet - Page 4

• Manufacturer Part Number: AN1740
• Description: Applications Using the Analog Subsystem on MC68HC05JJ/JP Series Microcontrollers
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
Channel
Multiplexer
Input Divider
Sample and Hold
On-Chip
Temperature
Sensing Diode
Control/Status
Registers
4
NOTE:
such as a capacitor, to be attached to PB0 and used as an integrator
which can be reset.
Voltage comparator 2 can be interconnected to external pins and
internal sources using a 6-channel multiplexer.
The channel selection multiplexer can feed a voltage divider which
allows the input signals to the channels to be higher than the common
mode range of voltage comparator 2.
A provision at the input of comparator 2 is made for a sample and hold
on an internal capacitor. The source for sample and hold can be the
output of either the channel multiplexers or the input divider.
The temperature of the device can be inferred by measuring the voltage
on the internal diode. This voltage can be measured using the simple
A/D convertor techniques discussed later.
To use these basic building blocks in typical analog interfaces, there is
an assortment of channel multiplexers, control logic, and three registers
containing 20 control bits and four status bits related to the analog
subsystem. All the registers relating to the analog subsystem are shown
in
These registers are:
Some analog features are enabled or disabled by an OPT bit. This OPT
bit is in the mask option register (MOR) in the EPROM versions or is
specified as a mask option on the ROM versions.
Figure
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Freescale Semiconductor, Inc.
For More Information On This Product,
Analog MUX register (AMUX) at $0003
Analog control register (ACR) at $001D
Analog status register (ASR) at $001E
2.
Go to: www.freescale.com
MOTOROLA
AN1740