I am using the 4 pin ultrasonic sensors and an arduino uno. I had modified a 15 ultrasonic sensor code for my purposes of using only 4. I see data from the first two, but not from sensor 3 or 4. I tried spreading them out more and putting things in between them to block each other. I also tried swapping the sensors around to different pins, and each sensor works as long as they are plugged into the sensor 1 (pins 2,3) and sensor 2 (pins4,5) spots. So I know I at least don't have two busted sensors. I don't think there is something wrong with my code, but I thought I might as well share it to see if someone else will spot something I missed.
// ---------------------------------------------------------------------------
// This example code was used to successfully communicate with 15 ultrasonic sensors. You can adjust
// the number of sensors in your project by changing SONAR_NUM and the number of NewPing objects in the
// "sonar" array. You also need to change the pins for each sensor for the NewPing objects. Each sensor
// is pinged at 33ms intervals. So, one cycle of all sensors takes 495ms (33 * 15 = 495ms). The results
// are sent to the "oneSensorCycle" function which currently just displays the distance data. Your project
// would normally process the sensor results in this function (for example, decide if a robot needs to
// turn and call the turn function). Keep in mind this example is event-driven. Your complete sketch needs
// to be written so there's no "delay" commands and the loop() cycles at faster than a 33ms rate. If other
// processes take longer than 33ms, you'll need to increase PING_INTERVAL so it doesn't get behind.
// ---------------------------------------------------------------------------
#include <NewPing.h>
#define SONAR_NUM 4 // Number or sensors.
#define MAX_DISTANCE 55 // Maximum distance (in cm) to ping.
#define PING_INTERVAL 33 // Milliseconds between sensor pings (29ms is about the min to avoid cross-sensor echo).
unsigned long pingTimer[SONAR_NUM]; // Holds the times when the next ping should happen for each sensor.
unsigned int cm[SONAR_NUM]; // Where the ping distances are stored.
uint8_t currentSensor = 0; // Keeps track of which sensor is active.
NewPing sonar[SONAR_NUM] = { // Sensor object array.
NewPing(2, 3, MAX_DISTANCE), // Each sensor's trigger pin, echo pin, and max distance to ping.
NewPing(4, 5, MAX_DISTANCE),
NewPing(6, 7, MAX_DISTANCE),
NewPing(8, 9, MAX_DISTANCE),
};
void setup() {
Serial.begin(9600);
pingTimer[0] = millis() + 75; // First ping starts at 75ms, gives time for the Arduino to chill before starting.
for (uint8_t i = 1; i < SONAR_NUM; i++) // Set the starting time for each sensor.
pingTimer[i] = pingTimer[i - 1] + PING_INTERVAL;
}
void loop() {
for (uint8_t i = 0; i < SONAR_NUM; i++) { // Loop through all the sensors.
if (millis() >= pingTimer[i]) { // Is it this sensor's time to ping?
pingTimer[i] += PING_INTERVAL * SONAR_NUM; // Set next time this sensor will be pinged.
if (i == 0 && currentSensor == SONAR_NUM - 1) oneSensorCycle(); // Sensor ping cycle complete, do something with the results.
sonar[currentSensor].timer_stop(); // Make sure previous timer is canceled before starting a new ping (insurance).
currentSensor = i; // Sensor being accessed.
cm[currentSensor] = 0; // Make distance zero in case there's no ping echo for this sensor.
sonar[currentSensor].ping_timer(echoCheck); // Do the ping (processing continues, interrupt will call echoCheck to look for echo).
}
}
// The rest of your code would go here.
}
void echoCheck() { // If ping received, set the sensor distance to array.
if (sonar[currentSensor].check_timer())
cm[currentSensor] = sonar[currentSensor].ping_result / US_ROUNDTRIP_CM;
}
void oneSensorCycle() { // Sensor ping cycle complete, do something with the results.
for (uint8_t i = 0; i < SONAR_NUM; i++) {
Serial.print(cm[i]);
Serial.print(" ");
}
Serial.println();
}