MSP430 F5529 ultrasonic sensor for servo control

Hi Joshua,

There are tutorials on the web for interfacing the ultrasonic sensor with specific MSP devices, I provided links below and think they are a good place to start. Additional info on your setup as well as the code so far would be beneficial.

www.instructables.com/.../
karuppuswamy.com/.../


Sincerely,
Sean

I've got it to return values via the serial monitor so i know it works and is hooked up properly. I have the servo at 3v going to pin 2 and the ultrasonic sensor at 5v trig going to pin 3 and echo going to pin 4. This is the code I'm using. 

#include <Servo.h>



//Setup the variables for the HC-SR04

const int trigPin = 3;

const int echoPin = 4;

// create servo object to control a servo

// a maximum of eight servo objects can be created

Servo myservo;



// variable to store the servo position

int pos = 0;

void setup() {

// initialize serial communication:

Serial.begin(9600);



// attaches the servo on pin 9 to the servo object

myservo.attach(2);



}

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(2);

digitalWrite(trigPin, HIGH);

delayMicroseconds(10);

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);



//Tell the Arduino to print the measurement in the serial console

Serial.print(inches);

Serial.print("in, ");

Serial.print(cm);

Serial.print("cm");

Serial.println();



// This if-else statement tells the Arduino at what distance

// it should trigger the servo, what the servo should do,

// and what it should do if the distance is too far away.

if (inches <= 24) {sweep(3);



}

else if (inches >= 24) {myservo.write(pos);

}



// Tell the Arduino to wait 0.10 seconds before pinging the

// Ultrasonic Sensor again.

delay(100);

}

// Converts the microseconds reading to Inches

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: www.parallax.com/.../28015-PING-v1.3.pdf

return microseconds / 74 / 2;

}

//Converts the Microseconds Reading to Centimeters

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;

}

//This sub-routein is what dictates the movement of the servo

void sweep(int NUM_OF_CYCLES)



{

// Tells the Arduino to start this loop at 0 and incriment it by 1

// each time the loop completes. This is how the Arduino knows to

// stop the loop when a specific number of the
// Sweep routein has been ran.

for (int j=0; j<NUM_OF_CYCLES; j++)
// goes from 0 degrees to 180 degrees
for(pos = 0; pos < 180; pos += 1)
{ // in steps of 1 degree
// tell servo to go to position in variable 'pos'
myservo.write(pos);
// waits 15ms for the servo to reach the position delay(10); }
// goes from 180 degrees to 0 degrees
for(pos = 180; pos>=1; pos-=1) {
// tell servo to go to position in variable 'pos'
myservo.write(pos);
// waits 15ms for the servo to reach the position
delay(10); } }}

Hi Joshua,

It seems that your code is developed in Energia, I suggest the Energia forums to post this particular servo question as that forum is dedicated specifically for development in Energia.

forum.43oh.com/.../

Sincerely,
Sean

Hi Joshua,

Were you able to fix this problem.?
I will close this in the mean time pending a reply.

Regards,
Charles