Ultrasonic Distance Measurement With The Msp430

 This application report describes a distance-measuring system based on ultrasonic sound
utilizing the MSP430F413 ultralow-power Microcontroller The system transmits a burst of
ultrasonic sound waves towards the subject and then receives the corresponding echo. The
MSP430 integrated Analog Comparator Comparator_A is used to detect the arrival of the
echo to the system. The time taken for the ultrasonic burst to travel the distance from the
system to the subject and back to the system is accurately measured by the MSP430
Assuming the speed of sound in air at room temperature to be 1100 ft/s, the MSP430
computes the distance between the system and the subject and Displays it using a two-digit
static LCD driven by its integrated LCD Driver The distance is displayed in inches with an
accuracy of ±1 inch. The minimum distance that this system CAN measure is eight inches and
is limited by the transmitter’s transducer settling-time. The maximum distance that CAN be
measured is ninety-nine inches. The amplitude of the echo depends on the reflecting
material, shape, and size. Sound-absorbing targets such as carpets and reflecting surfaces
less than two square feet in area reflect poorly. The maximum measurable range is lower for
such subjects. If the amplitude of the echo received by the system is so low that it is not
detectable by the Comparator_A, the system goes out of range. This is indicated by
displaying the error message E.
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Ultrasonic Distance Measurement With the MSP430 Circuit Schematic
Ultrasonic Distance Measurement With the MSP430  Circuit Schematic

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