Friday, September 30, 2016

Embedded System Glossary – C

Embedded System Terminology - C

Cache - Very fast memory that holds copies of a subset of main memory, to allow for faster CPU access to data and instructions typically stored in main memory.
Capacitor - Used to store electrostatic energy, a capacitor is basically made up of conductors (two parallel metal plates), separated by an insulator (a dielectric such as: air, ceramic, polyester, mica, etc.). The energy, itself, is stored in an electric field created between the two plates given the right environment.
Cathode - (1) The positively charged pole (terminal) of a voltage source. (2) The negatively charged electrode of a device (diode) that acts as an electron source.
Cation - A positive ion, meaning an atom that has lost electrons.
Cavity Resonator - A component that contains and maintains an oscillating electromagnetic field.
Central Processing Unit (CPU) - (1) The master/main processor on the board. (2) The processing unit within a processor that is responsible for executing the indefinite cycle of fetching, decoding, and executing instructions while the processor has power.
Checksum - A numerical value calculated from some set of data to verify the integrity of that data, commonly used for data transmitted via a network.
Chip - See Integrated Circuit (IC).
Circuit - A closed system of electronic components in which a current can flow.
Circuit Breaker - An electrical component that insures that a current load doesn’t get too large by shutting down the circuit when its overheat sensor senses there is too much current.
Class - Used in object-oriented schemes and languages to create objects, a class is a prototype (type description) that is made up of some combination of interfaces, functions (methods), and variables.
Clear-box Testing - See White-box Testing.
Clock - An oscillator that generates signals resulting in some type of waveform. Most embedded boards include a digital clock that generates a square waveform.
Coaxial - Cable A type of cabling made up of two layers of physical wire, one center wire and one grounded wire shielding. Coaxial cables also include two layers of insulation, one between the wire shielding and center wire, and one layer above the wire shielding. The shielding allows for a decrease in interference (electrical, RF, etc.).
Compiler A software tool that translates source code into assembly code, an intermediary language opcode, or into a processor’s machine code directly.
Complex Instruction Set - Computer (CISC) A general-purpose ISA which typically is made up of many, more complex operations and instructions than other general-purpose ISAs.
Complex Programmable Logic Device - A larger, more capable PLD
Computer Aided Design (CAD) Tools - Tools used to create technical drawings and documentation of the hardware, such as schematic diagrams.
Computer Aided Software Engineering (CASE) Tools - Design and development tools that aid in creating an architecture and implementing a system, such as UML tools and code generators.
Conductor - A material that has fewer impediments to an electric current (meaning it more easily loses/gains valence electrons) allowing for an electrical current to flow more easily through them than other types of materials. Conductors typically have <=3 valence electrons.
Connector - An electrical component that interconnects different types of subsystems.
Context - The current state of some component within the system (registers, variables, flags, etc.).
Context Switch - The process in which a system component (interrupts, an OS task, etc.) switches from one state to another.
Coprocessor - A slave processor that supports that master CPU by providing additional functionality and that has the same ISA as the master processor.
Coulomb - In electronics, the charge of one electron is too small to be of practical use, so in electronics, the unit for measuring charges is called a Coulomb (named after Charles Coulomb who founded Coulomb’s law), and is equal to that of 6.28 x 1018 electrons.
Counter/Timer - A common peripheral that counts either external events (counter mode) or processor cycles (timer mode)
Counting Semaphore - A type of semaphore with more than two states. A counting semaphore is typically used to track multiple resources of the same type. An attempt to take a counting semaphore is blocked only if all of the available resources are in use.
Cyclic Redundancy Check (CRC) - A check value calculated from the data, to catch most transmission errors. A decoder calculates the CRC for the received data and compares it to the CRC that the encoder calculated, which is appended to the data. A mismatch indicates that the data was corrupted in transit. Depending on the algorithm and number of CRC bits, come CRCs contain enough redundant information that they can be used to correct the data.
Critical Section - A set of instructions that are flagged to be executed without interruption.
Cross Compiler - A compiler that generates machine code for hardware platforms that differs from the hardware platform the compiler is actually residing and running on.
Crystal - An electrical component that determines an oscillator’s frequency. A crystal is typically made up of two metal plates separated by quartz, with two terminals attached to each plate. The quartz within a crystal vibrates when current is applied to the terminals, and it is this frequency that impacts the frequency at which the oscillator operates.
Current - A directed flow of moving electrons.

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Related topics:
Embedded System Architecture   |   Embedded Hardware Architecture   |   Embedded Software Architecture   |   Embedded Software Definition   |   Embedded System Acronyms   |   Embedded System Symbols

List of topics: Embedded System

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