Four 4-Pin Ultrasonic Sensors?

I started with one 4-pin ultrasonic sensor. I got it working great with an arduino uno, and sending data to Max MSP. I wanted to expand my project to 4 sensors, but I'm having some troubles. It appears that I am only receiving data from the first sensor. The other problem is that the data coming in is much slower than when I was using my other one sensor code. I think it is an arduino code issue, and I've been fiddling around with modifying my one sensor code, as well as modifying someone else's 3 sensor code. But I can't seem to get it to work.

Here is what I think is my best attempted code for four sensors:

#define trigPin1 2
#define echoPin1 3
#define trigPin2 4
#define echoPin2 5
#define trigPin3 6
#define echoPin3 7
#define trigPin4 8
#define echoPin4 9

long duration, distance, Sensor1,Sensor2, Sensor3, Sensor4;

void setup()
{
Serial.begin (9600);
pinMode(trigPin1, OUTPUT);
pinMode(echoPin1, INPUT);
pinMode(trigPin2, OUTPUT);
pinMode(echoPin2, INPUT);
pinMode(trigPin3, OUTPUT);
pinMode(echoPin3, INPUT);
pinMode(trigPin4, OUTPUT);
pinMode(echoPin4, INPUT);
}

void loop() {
SonarSensor(trigPin1, echoPin1);
Sensor1 = distance;
SonarSensor(trigPin2, echoPin2);
Sensor2 = distance;
SonarSensor(trigPin3, echoPin3);
Sensor3 = distance;
SonarSensor(trigPin4, echoPin4);
Sensor4 = distance;

Serial.print(Sensor1);
Serial.print(" - ");
Serial.print(Sensor2);
Serial.print(" - ");
Serial.println(Sensor3);
Serial.print(" - ");
Serial.println(Sensor4);
}

void SonarSensor(int trigPin,int echoPin)
{
digitalWrite(trigPin, LOW);
delayMicroseconds(2);
digitalWrite(trigPin, HIGH);
delayMicroseconds(10);
digitalWrite(trigPin, LOW);
duration = pulseIn(echoPin, HIGH);
distance = (duration/2) / 29.1;

}

@ CLK

Hey man,
Have you checked out the library example for the NewPing.h library?
Open up the New Ping 3 sensors example> edit in for one more sensor. Easy.

Yes that looks very very similar to the one I was using for only one ultrasonic sensor. I am having issues trying to get it to work for four sensors. Here is the code that I used for just one sensor, so you can compare what I did for one, against what I attempted to do for four (above in first post).

/* HC-SR04 Sensor

https://www.dealextreme.com/p/hc-sr04-ultrasonic-sensor-distance-measuring-module-133696
This sketch reads a HC-SR04 ultrasonic rangefinder and returns the
distance to the closest object in range. To do this, it sends a pulse
to the sensor to initiate a reading, then listens for a pulse
to return. The length of the returning pulse is proportional to
the distance of the object from the sensor.
The circuit:

* VCC connection of the sensor attached to +5V
* GND connection of the sensor attached to ground
* TRIG connection of the sensor attached to digital pin 7
* ECHO connection of the sensor attached to digital pin 6


Original code for Ping))) example was created by David A. Mellis
Adapted for HC-SR04 by Tautvidas Sipavicius

This example code is in the public domain.
*/


const int trigPin = 2;
const int echoPin = 3;

void setup() {
// initialize serial communication:
Serial.begin(9600);
}

void loop() {
// establish variables for duration of the ping,
// and the distance result in inches and centimeters:
long duration, inches, cm;

// The sensor is triggered by a HIGH pulse of 10 or more microseconds.
// Give a short LOW pulse beforehand to ensure a clean HIGH pulse:
pinMode(trigPin, OUTPUT);
digitalWrite(trigPin, LOW);
delayMicroseconds(5);
digitalWrite(trigPin, HIGH);
delayMicroseconds(15);
digitalWrite(trigPin, LOW);

// Read the signal from the sensor: a HIGH pulse whose
// duration is the time (in microseconds) from the sending
// of the ping to the reception of its echo off of an object.
pinMode(echoPin, INPUT);
duration = pulseIn(echoPin, HIGH);

// convert the time into a distance
inches = microsecondsToInches(duration);
cm = microsecondsToCentimeters(duration);
Serial.write(inches);
Serial.write("in, ");
Serial.write(cm);
Serial.write("cm");
Serial.write(cm);
delay(100);
}

long microsecondsToInches(long microseconds) {
// According to Parallax's datasheet for the PING))), there are
// 73.746 microseconds per inch (i.e. sound travels at 1130 feet per
// second). This gives the distance travelled by the ping, outbound
// and return, so we divide by 2 to get the distance of the obstacle.
// See: http://www.parallax.com/dl/docs/prod/acc/28015-PING-v1.3.pdf
return microseconds / 74 / 2;
}

long microsecondsToCentimeters(long microseconds) {
// The speed of sound is 340 m/s or 29 microseconds per centimeter.
// The ping travels out and back, so to find the distance of the
// object we take half of the distance travelled.
return microseconds / 29 / 2;
}

the data coming in is much slower than when I was using my other one sensor code.

It takes four times as long to collect data from four sensors, than it does from one.