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Electronics
C
CAN:
Controller Area Network
The
Controller Area Network, or CAN, protocol is a serial communication protocol
originally developed by Robert Bosch GmbH for use in serial communication
networks in vehicles. Several major auto manufacturers are either currently
using CAN networks in their vehicles or are developing them for future vehicles.
In addition, CAN is becoming very popular for use in factory-floor
automation-type industrial networks. The major players in industrial automation,
including Allen-Bradley, Honeywell and Eaton Cutler-Hammer are all manufacturing
CAN-based industrial control systems, and are publicizing their beliefs that the
CAN protocol is the best solution for this type of control network.
The CAN specification addresses the
lowest two layers of the ISO's Open Systems Interconnect (OSI) Reference model
for communication protocols, the Data Link Layer and the Physical Layer.
However, while certain aspects of the Physical Layer are addressed by the CAN
protocol, its primary purpose is to define the aspects of the Media Access
Control (MAC) sub layer and a small part of the Logical Link Control (LLC) sub
layer of the Data Link Layer. Almost all aspects of the Physical Layer (data
rate, choice of media, etc) are left to the user.
CCTV:
Closed Caption Television
The closed caption television (CCTV)
module is used in television receivers, set-top decoders, or VCRs conforming to
the NTSC standard. A programmable data slicer (DSL) extracts closed-caption
compatible data from an NTSC composite video signal for closed-caption and
extended data services applications. Once the data is extracted an on-screen
display system (OSD) displays the data on the television screen.
CGM:
Clock Generator Module
The Clock Generator Module (CGM) is a
68HC08 module that generates two different clock signals from a user-selected
source. The crystal clock signal is buffered by the CGM and used by the SCI baud
rate generator and the COP watchdog timer. In addition, the output clock of the
CGM, generated by either the crystal clock or an on-board phased-lock loop
clock, is used by the SIM, which drives internal bus clocks. The on-board
phased-lock loop can be used to generate maximum bus speed (8 MHz)
cost-effectively (1 MHz to 16 MHz external crystal).
COP:
Computer Operating Properly
CPU:
Central Processing Unit
The Central Processing Unit (CPU)
processes information in accordance with a program of instructions and data in a
particular language called "machine code". The CPU controls all the
system operations and provides control signals for enabling and disabling the
various peripherals and I/O devices. In addition to the accumulator, the CPU's
core has an index register, a 5-bit stack pointer, and a 5-bit condition code
register. The instruction set features 10 uncomplicated addressing modes
including 8 and 16-bit indexing from the 16-bit program counter. Bit
manipulation instructions are provided to set, clear, test, or jump based on a
bit value anywhere in the memory map. Math functions include add, subtract, and
multiply.
Wait mode reduces power consumption by
approximately 50% by discontinuing CPU processing. The clock continues to run in
wait mode in order to service interrupts immediately. Stop mode stops the clock
and all internal processing to reduce power consumption to micoroamps. Both
modes maintain memory and enable an interrupt to wake up the CPU.
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