Oscillator start-up timer

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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. [1] [2] 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. [3]

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References

  1. PIC tutorials - PIC16x8x, retrieved 27 October 2011
  2. Maxim - Crystal Considerations with Maxim Real-Time Clocks, retrieved 27 October 2011
  3. Microchip - reset, retrieved 27 October 2011