IntOff

Syntax:

    IntOff

Command Availability:

Available on Microchip PIC and Atmel AVR microcontrollers with interrupt support. Will be automatically removed on chips without interrupts.

Explanation:

IntOff is used to disable interrupts on the microcontroller. It should be used at the start of code that is timing-sensitive, and which would not function correctly if paused and restarted partway through.

It is essential that IntOn is used to turn interrupts back on after the timing-sensitive code has finished running. If it is not, no interrupts will be handled for the rest of the program.

It is recommended that IntOff be placed before all timing-sensitive code, in case interrupts are implemented later.

IntOff is removed from the assembled output if no interrupts are used anywhere in the program.

Example:

    #chip 16F628A, 4

    Dim CriticalValue As Word

    IntOff          ' <<< the IntOff instruction
    CriticalValue = ReadAD(AN0) * 2 + 1
    IntOn

Key line: IntOff — disables interrupts before the timing-sensitive read-and-calculate sequence, so an interrupt cannot pause it partway through; IntOn below restores normal interrupt handling once the sequence is complete.

See Also:

  • IntOn — re-enabling interrupts after IntOff
  • Interrupts — category overview
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