Using Ultrasonic sensor to control a Stepper

Using Arduino Sensors
1

Hi guys.
I've been trying to read a Ultrasonic sensor HC-SR04 using the NewPing library to control a bipolar stepper motor, without using any library for the stepper cotrol, which i suceeded.
However, i'm still having a little issue while the motor is moving. I've set the readings to happen every 125ms, or 8 times per seconds, and during the readings, the stepper motor moves with little bumps, the same thing that happens by using de pulseIn command, which the program stops and waits for the Echo pulse to happen. I'm posting my code below, and ask if you guys see any mistakes that i may have done.

#include <NewPing.h>

const int pulsePin =  LED_BUILTIN;// the number of the LED pin
bool flagEnable = LOW;
int pulseState = LOW;

// constants won't change:
const long intervalServ = 250;

unsigned long previousMillis = 0;
unsigned long interval = 125;
unsigned long pingTimer = 0;
double distance = 0;

void echoCheck();

#define TRIGGER_PIN  6
#define ECHO_PIN     5
#define MAX_DISTANCE 200

NewPing sonar(TRIGGER_PIN, ECHO_PIN, MAX_DISTANCE);

void setup() {
  // set the digital pin as output:
  pinMode(pulsePin, OUTPUT);
  pinMode(12, OUTPUT);
  pinMode(11, INPUT_PULLUP);
  unsigned long pingTimer = millis();
  Serial.begin(9600);
}

void loop() {
  unsigned long currentMillis = micros();
  unsigned long tEnable = millis();
  if (millis() >= pingTimer) {   // pingSpeed milliseconds since last ping, do another ping.
    pingTimer += interval;      // Set the next ping time.
    sonar.ping_timer(echoCheck); // Send out the ping, calls "echoCheck" function every 24uS where you can check the ping status.
  }
  distance = sonar.ping_result / US_ROUNDTRIP_CM;
  if (distance >= 5.0) {
    flagEnable = HIGH;
    digitalWrite(12, flagEnable);
  }
  else {
    flagEnable = LOW;
    digitalWrite(12, flagEnable);
  }
  if (currentMillis - previousMillis >= intervalServ) {
    // save the last time you blinked the LED
    previousMillis = currentMillis;

    if (pulseState == LOW) {
      pulseState = HIGH;
      currentMillis = micros();
    } else {
      pulseState = LOW;
      currentMillis = micros();
    }
    digitalWrite(pulsePin, pulseState);
  }
   
}
void echoCheck() { // Timer2 interrupt calls this function every 24uS where you can check the ping status.
  // Don't do anything here!
  if (sonar.check_timer()) { // This is how you check to see if the ping was received.
    // Here's where you can add code.
    Serial.print("Ping: ");
    Serial.print(sonar.ping_result / US_ROUNDTRIP_CM); // Ping returned, uS result in ping_result, convert to cm with US_ROUNDTRIP_CM.
    Serial.println("cm");
  }
}
2

From your description, it is not entirely clear what the problem is, or how you are controlling the motor.

Please post a complete wiring diagram, and links to the stepper motor, stepper driver and stepper power supply.

3

It is very confusing to store valus from micros() in a variable called currentMillis. And it is very confusing too, if your comment tells about a LED where you obviously create the step pulses - at least that's what I assume.

It is not a good idea, to have Serial prints in a function, that is called by an interrupt every 24µs - or is this comment rubbish too?

I think you sonar calls will block the loop for a few milliseconds - what gives the 'bumps' to the stepper, because the steppulses are delayed.

4

Bipolar stepper motor, wired to a HSS60 driver, with its pulse pin wired to the 13 pin on the arduino board, very simple by the way.
I am controlling the pulses using the micros() function.
The problem is, everytime i call the distance measuring function, the motor makes a short bump, as if the program stopped during the measuring function.

5

That's exactly what I supposed ( see above ).

6

Then what should i do to avoid this delay on the step pulses? I thought that using the New ping library, the program would no longer stop during the calls.

7

I don't know this library, but maybe you are disturbing it by the Serial.prints in the echoCheck() function.

8

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