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Oscillator Start-up Timer
An oscillator start-up timer (OST) is a module used by some microcontrollers to keep the device reset until the crystal oscillator is stable. When a crystal oscillator starts up, its frequency is not constant, which causes the clock frequency to be non-constant. This would cause timing errors, leading to many problems. An oscillator start-up timer ensures that the device only operates when the oscillator generates a stable clock frequency. The PIC microcontroller's oscillator start-up timer holds the device's reset for a 1024-oscillator-cycle delay to allow the oscillator to stabilize. retrieved 27 October 2011 See also * *[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microcontroller
A microcontroller (MCU for ''microcontroller unit'', often also MC, UC, or μC) is a small computer on a single VLSI integrated circuit (IC) chip. A microcontroller contains one or more CPUs ( processor cores) along with memory and programmable input/output peripherals. Program memory in the form of ferroelectric RAM, NOR flash or OTP ROM is also often included on chip, as well as a small amount of RAM. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications consisting of various discrete chips. In modern terminology, a microcontroller is similar to, but less sophisticated than, a system on a chip (SoC). An SoC may connect the external microcontroller chips as the motherboard components, but an SoC usually integrates the advanced peripherals like graphics processing unit (GPU) and Wi-Fi interface controller as its internal microcontroller unit circuits. Microcontrollers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crystal Oscillator
A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers. The most common type of piezoelectric resonator used is a quartz crystal, so oscillator circuits incorporating them became known as crystal oscillators. However, other piezoelectricity materials including polycrystalline ceramics are used in similar circuits. A crystal oscillator relies on the slight change in shape of a quartz crystal under an electric field, a property known as inverse piezoelectricity. A voltage applied to the electrodes on the crystal causes it to change shape; when the voltage is removed, the crystal generates a small voltage as it elastically returns to its original shape. The quartz oscillates at a stable ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clock Signal
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits. A clock signal is produced by a clock generator. Although more complex arrangements are used, the most common clock signal is in the form of a square wave with a 50% duty cycle, usually with a fixed, constant frequency. Circuits using the clock signal for synchronization may become active at either the rising edge, falling edge, or, in the case of double data rate, both in the rising and in the falling edges of the clock cycle. Digital circuits Most integrated circuits (ICs) of sufficient complexity use a clock signal in order to synchronize different parts of the circuit, cycling at a rate slower than the worst-case internal propagation delays. In some cases, more than one clock cycle is required to perform a predictable action. As ICs bec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PIC Microcontroller
PIC (usually pronounced as ''"pick"'') is a family of microcontrollers made by Microchip Technology, derived from the PIC1650"PICmicro Family Tree", PIC16F Seminar Presentation originally developed by General Instrument's Microelectronics Division. The name PIC initially referred to ''Peripheral Interface Controller'',"MOS DATA 1976", General Instrument 1976 Databook and is currently expanded as ''Programmable Intelligent Computer''."1977 Data Catalog", Micro Electronics from General Instrument Corporation The first parts of the family were available in 1976; by 2013 the company had shipped more than twelve billion individual parts, used in a wide variety of embedded systems. The PIC was originally intended to be used with the General Instrument CP1600, the first commercially available single-chip 16-bit microprocessor. The CP1600 had a complex bus that made it difficult to interface with, and the PIC was introduced as a companion device offering ROM for program storage ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Power-on Reset
A power-on reset (PoR, POR) generator is a microcontroller or microprocessor peripheral that generates a reset signal when power is applied to the device. It ensures that the device starts operating in a known state. PoR generator In VLSI devices, the power-on reset (PoR) is an electronic device incorporated into the integrated circuit that detects the power applied to the chip and generates a reset impulse that goes to the entire circuit placing it into a known state. A simple PoR uses the charging of a capacitor, in series with a resistor, to measure a time period during which the rest of the circuit is held in a reset state. A Schmitt trigger may be used to deassert the reset signal cleanly, once the rising voltage of the RC network passes the threshold voltage The threshold voltage, commonly abbreviated as Vth or VGS(th), of a field-effect transistor (FET) is the minimum gate-to-source voltage (VGS) that is needed to create a conducting path between the source and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Brown-out Reset
Brownout may refer to: * Brownout (electricity), drop in voltage in an electrical power supply, so named because it typically causes lights to dim * Brownout (software engineering), a technique inspired by brownout in electricity, to make applications more tolerant to capacity shortages * Brownout (aeronautics), reduced flight visibility due to airborne particles, especially from helicopter downwash * ''Brownout'' (album), studio album by American band Head Set * Brownout (band), a band from Austin, Texas See also * Greyout, a dimming of the vision caused by loss of blood pressure or hypoxia * Redout, affected vision caused by increased blood flow to the head * Blackout (other) * Whiteout (other) * Eddie Leonski Edward Joseph Leonski (December 12, 1917 – November 9, 1942) was a United States Army soldier and serial killer responsible for the strangling murders of three women in Melbourne, Australia in 1942. Leonski was dubbed The Brownout Strangler ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Watchdog Timer
A watchdog timer (sometimes called a ''computer operating properly'' or ''COP'' timer, or simply a ''watchdog'') is an electronic or software timer that is used to detect and recover from computer malfunctions. Watchdog timers are widely used in computers to facilitate automatic correction of temporary hardware faults, and to prevent errant or malevolent software from disrupting system operation. During normal operation, the computer regularly restarts the watchdog timer to prevent it from elapsing, or "timing out". If, due to a hardware fault or program error, the computer fails to restart the watchdog, the timer will elapse and generate a timeout signal. The timeout signal is used to initiate corrective actions. The corrective actions typically include placing the computer and associated hardware in a safe state and invoking a computer reboot. Microcontrollers often include an integrated, on-chip watchdog. In other computers the watchdog may reside in a nearby chip that connec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-voltage Detect
A low-voltage detect (LVD) is a microcontroller or microprocessor peripheral that generates a reset signal when the Vcc supply voltage falls below Vref. Sometimes is combined with power-on reset (POR) and then it is called POR-LVD. See also *Power-on reset A power-on reset (PoR, POR) generator is a microcontroller or microprocessor peripheral that generates a reset signal when power is applied to the device. It ensures that the device starts operating in a known state. PoR generator In VLSI d ... {{electronics-stub Embedded systems ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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