FVRIsOutputReady

Syntax:

    user_var = FVRIsOutputReady()

Command Availability:

Available on all Microchip microcontrollers with the Fixed Voltage Reference (FVR) module.

Explanation:

This function returns the state of the FVR.   The returned value can be assigned to a variable or used directly as a condition.

The method returns 0 or 1, as follows:

0 = Fixed Voltage Reference output is not ready or not enabled

1 = Fixed Voltage Reference output is ready for use

After FVRInitialize enables the FVR, the reference voltage takes a short time to stabilise. Reading the ADC before it stabilises can give an inaccurate result, so it is good practice to wait for FVRIsOutputReady to become true first.

Example:

    '// use FVR 4096 as Reference
    FVRInitialize ( FVR_4x )
    wait while FVRIsOutputReady = false          ' <<< the FVRIsOutputReady instruction
    ADVal = ReadAd(AN0)

Key line: wait while FVRIsOutputReady = false — blocks here until the FVR reports that its output has stabilised, so the following ReadAd call reads against a settled reference voltage.

See Also:

  • FVRInitialize — enabling the FVR and selecting its voltage
  • ReadAD — the ADC read this check protects the accuracy of
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