HC-SR04 Ultrasonic Sensor Library

This library can be used to read data from the HC-SR04 ultrasonic sensor.

Features

There are five methods in the Ultrasonic class.

1. Ultrasonic::CM and Ultrasonic::IN are static const class member objects on the Ultrasonic class.

2. long timing() This method reads data from the sensor. The return value is used for the microsec argument to the next method described below.

3. long convert(long microsec, int metric) This method converts the microsecond output of timing() passed to microsec to either centimeters or inches. The metric argument can be either of the two member object discribed in number one above.

4. void setDivisor(float value, int metric) This method permits the changing of the cm and in divisor so the accuracy of the sensor can be adjusted for distance. The value argument is taken from the table below and the metric argument is either of the two values from number one above.

5. bool sampleCreate(size_t size, ...) This method sets up the buffer(s) needed to derive the standard deviation. The size argument is the number of buffers that you will need. For each buffer, you need to pass an additional argument indication the length of that buffer. ex. bool success = sampleCreate(3, 10, 15, 8) This indicates that there will be three buffers each with lengths of 10, 15, 8 respectively. You should check the return value for true before proceeding with calling the two following methods.

6. void sampleClear() This method resets all the buffers to zero.

7. float unbiasedStdDev(long value, size_t bufNum) This method generates the standard deviation. The value argument can be the return value of either timing() or convert(). The bufNum argument is the ordinal number of the buffer meaning 0 - n. If you have defined three buffers the numbers would be 0, 1, 2.

Divisor Chart

Inches

Centimeters

Python Serial Terminal

Also available is a serial terminal specifically written for gathering data for this project. It is a read only terminal and can create CSV files of the incoming data. It could be used with the standard deviation example sketch.

Usage: readSerial.py [h] -d <device> -c <CSV File> -s <Raw data dump file>

Options:
  -h, --help            show this help message and exit
  -d DEVICE, --device=DEVICE
                        Serial device
  -c CSVFILE, --csv=CSVFILE
                        CSV output filename
  -s STREAM, --stream=STREAM
                        Raw stream filename

The script can be found below:

Python Serial Terminal

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