Glossary - The HCS12/9S12: An Introduction to Software and Hardware Interfacing - page 830

Branch instruction An instruction that causes the program flow to change.
Break The transmission or reception of a low for at least one complete character time.
Breakpoint A memory location in a program where the user program execution will be
stopped and the monitor program will take over the CPU control and display the contents
of CPU registers.
Bubble sort A simple sorting method in which an array or a file to be sorted is gone through
sequentially several times. Each iteration consists of comparing each element in the array
or file with its successor ( x [ i ] with x [ i + 1]) and interchanging the two elements if they are
not in proper order (either ascending or descending)
Bus A set of signal lines through which the processor of a computer communicates with
memory and I/O devices.
Bus cycle timing diagram A diagram that describes the transitions of all the involved signals
during a read or write operation.
Bus multiplexing A technique that allows more than one set of signals to share the same
group of bus lines.
Bus off The situation in which a CAN node has a transmit error count above 256.
CAN transceiver A chip used to interface a CAN controller to the CAN bus.
Central processing unit (CPU)

The combination of the register file, the ALU, and the

control unit.
Charge pump A circuit technique that can raise a low voltage to a level above the power
supply. A charge pump is often used in an A/D converter, in EEPROM and EPROM
programming, and so on.
Clock monitor reset A mechanism that detects whether the frequency of the system clock
signal inside a CPU is lower than a certain value.
Clock stretching In the I 2 C protocol, the SCL bus signal driven low for an interval longer than
the master's SCL low period by the slave device when it needs more time to make data ready.
Column address strobe (CAS) The signal used by DRAM chips to indicate that column
address logic levels are applied to the address input pins.
Comment A statement that explains the function of a single instruction or directive or a
group of instructions or directives. Comments make a program more readable.
Communication program A program that allows a PC to communicate with another computer.
Computer An electronic device consisting of hardware, that includes four major parts: the
central processing unit, the memory unit, the input unit, and the output unit; and software
that is a sequence of instructions that controls the operations of the hardware.
Computer operate properly (COP) watchdog timer A special timer circuit designed to detect
software processing errors. If software is written correctly, then it should complete all
operations within a certain amount of time. Software problems can be detected by enabling
a watchdog timer so that the software resets the watchdog timer before it times out.
Contact bounce A phenomenon in which a mechanical key switch will go up and down
several times before it settles down when it is pressed.
Control unit The part of the processor that decodes and monitors the execution of instructions.
It arbitrates the use of computer resources and makes sure that all computer operations are
performed in proper order.
Controller Area Network (CAN) A serial communication protocol initially proposed to be
used in automotive applications. In this protocol, data is transferred frame by frame. Each
frame can carry up to 8 bytes of data. Each data frame is acknowledged in frame.