An oscillator start-up timer (OST) is a module used by some
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 programma ...
s to keep the device reset until the
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 ...
is stable. When a crystal oscillator starts up, its frequency is not constant, which causes the
clock
A clock or a timepiece is a device used to measure and indicate time. The clock is one of the oldest human inventions, meeting the need to measure intervals of time shorter than the natural units such as the day, the lunar month and t ...
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
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 ...
's oscillator start-up timer holds the device's reset for a 1024-oscillator-cycle delay to allow the oscillator to stabilize.
Microchip - reset
retrieved 27 October 2011
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 ...
* Brown-out reset
*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 ...
* Low-voltage detect
References
Embedded systems
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