Issue with infinite loop on multiple servo program

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#1

Hi, below is my code for running three servos. I am only getting a signal on the first servo and doesn’t seem to change if I move things around. Looks like “myservoa.attach(7);” is good but the other servo attach lines are thrown out. Help is greatly appreciated. Thanks

#include <Servo.h>

Servo myservoa, myservob, myservoc;

void setup() {
  myservoa.attach(7);  // attaches the servo on pin 9 to the servo object
  myservob.attach(8);
  myservoc.attach(9);
}

void loop() {
  for (int pos = 1400; pos <= 1700; pos += 1) {
    myservoa.writeMicroseconds(pos);   
    delay(5);                        
  }
  for (int pos = 1700; pos >= 1400; pos -= 1) {
    myservoa.writeMicroseconds(pos);   
    delay(5);                         
  }
  for (int pos = 1000; pos >= 1500; pos -= 1) { 
    myservob.writeMicroseconds(pos);            
    delay(5);                      
  }
    for (int pos = 1500; pos <= 1000; pos += 1) { 
    myservob.writeMicroseconds(pos);             
    delay(5);                     
  }
  for (int pos = 1000; pos >= 1500; pos -= 1) {
    myservoc.writeMicroseconds(pos);            
    delay(5);                       
  }
    for (int pos = 1500; pos <= 1000; pos += 1) { 
    myservoc.writeMicroseconds(pos);  
    delay(5); 
  }
}
#2

I'm no C expert but is this kosher?

Servo myservoa, myservob, myservoc;

Try:

Servo myservoa;
Servo myservob;
Servo myservoc;
#3

That's what I used before, no go. I should say that I am using a Sparkfun Redboard...

#4

JimboZA:
I'm no C expert but is this kosher?

If you are not an expert, don't muddy the waters!

#5

Nothing to do with the attach() calls.

Your first error is on this line - can you spot it?

  for (int pos = 1000; pos >= 1500; pos -= 1) {
#6

MarkT, I assume you are talking about calling the var pos inside the loop. I had it outside the for loop as a global var before and no dice.

However, it works now that I initialized the var in the void loop().

#include <Servo.h>

Servo myservoa;
Servo myservob;
Servo myservoc;

void setup() {
  myservoa.attach(7);
  myservob.attach(8);
  myservoc.attach(9);
}

void loop() {
  
  int position;
  
 for(position = 70; position < 120; position += 1)
  {
    myservoa.write(position);  
    delay(20);               
  }
  for(position = 120; position >= 70; position -= 1)
  {                                
    myservoa.write(position); 
    delay(20);               
  }
   for(position = 70; position < 120; position += 1)
  {
    myservob.write(position);  
    delay(20);              
  }
  for(position = 120; position >= 70; position -= 1)
  {                                
    myservob.write(position);  
    delay(20);               
  }
   for(position = 70; position < 120; position += 1)
  {
    myservoc.write(position);  
    delay(20);               
  }
  for(position = 120; position >= 70; position -= 1)
  {                                
    myservoc.write(position);  
    delay(20);               
  }
}
#7

MarkT, I assume you are talking about calling the var pos inside the loop.

You can't call a variable. You can only call functions.

The for statement that MarkT showed says "Starting with pos = 1000, while pos is greater than or equal 1500, do stuff and then decrement pos by 1." How many times will that loop iterate? Does the number zero ring a bell?

#8

Ah! I see, had my arrows backwards.

#9