Distance detection techniques with MaxSonar ultrasonic rangefinder by Bruce Allen
- Analog.
- PW – Pulse Width.
Analog
//Feel free to use this code.
//Please be respectful by acknowledging the author in the code if you use or modify it.
//Author: Bruce Allen
//Date: 23/07/09
//Analog pin 1 for reading in the analog voltage from the MaxSonar device.
//This variable is a constant because the pin will not change throughout execution of this code.
const int anPin = 1;
//variables needed to store values
long anVolt, inches, cm;
int sum=0;//Create sum variable so it can be averaged
int avgrange=60;//Quantity of values to average (sample size)
void setup() {
//This opens up a serial connection to shoot the results back to the PC console Serial.begin(9600);
}
void loop() {
pinMode(anPin, INPUT);
//MaxSonar Analog reads are known to be very sensitive. See the Arduino forum for more information.
//A simple fix is to average out a sample of n readings to get a more consistant reading.\\
//Even with averaging I still find it to be less accurate than the pw method.\\
//This loop gets 60 reads and averages them
for(int i = 0; i < avgrange ; i++)
{
//Used to read in the analog voltage output that is being sent by the MaxSonar device.
//Scale factor is (Vcc/512) per inch. A 5V supply yields ~9.8mV/in
anVolt = analogRead(anPin);
sum += anVolt;
delay(10);
}
inches = sum/avgrange;
cm = inches * 2.54;
Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print("cm");
Serial.println();
//reset sample total sum = 0;
delay(500);
}
PW
I found this to be more accurate than the analog method and just as easy to implement.
//Feel free to use this code.
//Please be respectful by acknowledging the author in the code if you use or modify it.
//Author: Bruce Allen
//Date: 23/07/09
//Digital pin 7 for reading in the pulse width from the MaxSonar device.
//This variable is a constant because the pin will not change throughout execution of this code.
const int pwPin = 7;
//variables needed to store values
long pulse, inches, cm;
void setup() {
//This opens up a serial connection to shoot the results back to the PC console Serial.begin(9600);
}
void loop() {
pinMode(pwPin, INPUT);
//Used to read in the pulse that is being sent by the MaxSonar device. //Pulse Width representation with a scale factor of 147 uS per Inch. pulse = pulseIn(pwPin, HIGH); //147uS per inch inches = pulse/147; //change inches to centimetres cm = inches * 2.54;
Serial.print(inches);
Serial.print("in, ");
Serial.print(cm);
Serial.print("cm");
Serial.println();
delay(500);
}
