INTERNAL TRIGGER ERRORS IN MICROCONTROLLER-BASED MEASUREMENTS

Ferran Reverter, Josep Jordana, Ramon Pallàs-Areny

Abstract

Measurements based on triggering a time counter display trigger uncertainty, which depends on input signal noise and slew rate, and on input channel noise. This last is specified for bench-top instruments but not for microcontrollers with embedded time counters, which are very attractive to implement period-to-code converters intended for sensor interfaces. Because power-supply rails in digital systems are very noisy, we have analysed the effect of Gaussian white noise and sine wave interference added to the PIC16F873 power supply pin. For a triangular input signal, the standard deviation of 1000 period readings increases with the amplitude of the added noise, as expected, and it is always larger when the period is determined from the rising edge of the timed signal rather than from its falling edge.

Keywords

Period measurement, trigger noise, microcontroller

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PWC-2003-TC4-047.pdf

DOI

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IMEKO TC

TC4 - Measurement of Electrical Quantities

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