I have been struggling with arduino and ultrasonic sensor HC-SR04 and PWM. I am using arduino pro mini. Also using NewPing library.
the newping library example works perfectly if I have just the sonar attached and I get about 170cm when pointing upwards towards the ceiling.
However if I add a pwm call on a different pin(pin 3 in this case) the sonar outputs maximum of 41cm, everything below that works, albeit bit noisily.
I have almost nothing connected to the pwm pin, there is only a capasitor and a resistor. I had a motor as well but removed it for debugging.
Illustration of my wiring:
code:
#include <NewPing.h>
#define TRIGGER_PIN 8 // Arduino pin tied to trigger pin on the ultrasonic sensor.
#define ECHO_PIN 7 // Arduino pin tied to echo pin on the ultrasonic sensor.
#define MAX_DISTANCE 200
NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE);
int p = 3;
void setup() {
// put your setup code here, to run once:
pinMode(p,OUTPUT);
Serial.begin(115200);
}
void loop() {
delay(50); // Wait 50ms between pings (about 20 pings/sec). 29ms should be the shortest delay between pings.
Serial.print("Ping: ");
int d = sonar.ping_cm();
Serial.print(d); // Send ping, get distance in cm and print result (0 = outside set distance range)
Serial.println("cm");
analogWrite(p,d);
}
The problem does disappear if I remove everything from the pin 3, but I don't see how this wiring can have any effect, especially with the motor missing.
Any ideas how to get the sonar and pwm working at the same time.
