@will I know, I know, teacher teacher ask me!

Posted by: @zander

 

I know, I know, teacher teacher ask me!

So, they could be 'void'. I know it is good form to write return(0); for an int function that doesn't actually return a value. The Arduino IDE and the GCC don't seem to mind. I will try them as 'void', but I have to get to bed. The alarm goes off a 5:00 am. Thanks for all the advice.

Posted by: @zoolandermicro

I know it is good form to write return(0); for an int function that doesn't actually return a value.

Actually, if an int function doesn't return an int, then it shouldn't be an int function. It's not wise to risk angering the compiler 🙂

@will Back in the day, my rule was to set the compiler to show EVERY message including warnings. That meant no implicit casts, everything had to be specified. It teaches thoroughness and good form. I did get pushback until I showed that one level W or I not sure anymore, could result in a runtime crash under not farfetched circumstances. The benefit of being specific was a 50% speed gain for the operation. That makes it far more important than 'just' cosmetic.

Any way, I had a chance to clean up my code (as per suggestions). Looks nice, but the thirteenth servo still does not attach. The robot's head doesn't reallyy need to move, it would just look cool. On the head is a sonic distance sensor. I can still run the obsticle avoidence code. If the head could sweep, the code could make a choice of moving left or right. That would be a nice tric. For your viewing pleasure I present my test code:

/*
  Adeept Hexapod test code written to test each of
  thriteen servos.
*/
#include <Servo.h>    //Servo control
#define servoData 13 //Number of servos
#define numSweeps 2 //Number of Hexapod head sweeps left and right
#define debug      //Comment out this line to disable serial output
const int MIN_ANGLE = 10;  //Minimum sweep angle of bot head
const int MAX_ANGLE = 170; //Maximum sweep angle of bot head
int angle[servoData] = {90, 90, 90, 90, 90, 90, 90, 90, 90, 90, 90, 90, 90};
Servo myServo[servoData];//Create servo object.Indecies 0 through 12 (13 servos)

void setup() {
#ifdef debug
  Serial.begin(9600); //For serial monitor output
#endif
  for (int index = 0; index < servoData; index++) { //Attach servos to pins 2 through 14
    myServo[index].attach(index + 2);
  }
  for (int index = 0; index < servoData; index++) { //Set all servos to 90 degree angle
    myServo[index].write(angle[index]);
  }
  delay(1000);//wait for a second
}
void loop() {
  for (int count = 0; count < servoData; count++) { //Counts from 0 - 12
    if (count <= 5) {                //Test range 0 - 5
      moveServos_L(count);          //Move servos on left side
    }
    else if (count > 5 && count < (servoData - 1)) { //Test range 6 - 11
      moveServos_R(count);       //Move servos on right side
    }
    else {                     //Value of 'count' is 12
      botHead_Sweep(count);   //Move head servo
    }
  }
}
//Functions
void moveServos_L(int servo) {      //Left side pivot and claw servos
  if (myServo[servo].attached()) { //If the servo is attached, proceed with the function
    myServo[servo].write(60);
    delay(500);
    myServo[servo].write(90);
    delay(500);
    myServo[servo].write(120);
    delay(500);
    myServo[servo].write(90);
    delay(500);
  } //End if
} //End function
void moveServos_R(int servo) {      //Right side pivot and claw servos
  if (myServo[servo].attached()) { //If the servo is attached, proceed with the function
    myServo[servo].write(120);
    delay(500);
    myServo[servo].write(90);
    delay(500);
    myServo[servo].write(60);
    delay(500);
    myServo[servo].write(90);
    delay(500);
  } //End if
} //End function
void botHead_Sweep(int servo) {       //Head servo pivots
  //if (myServo[servo].attached()) { //If the 13th servo is attached, proceed with the function
#ifdef debug
  Serial.print("Servo ");
  Serial.print(servo);
  Serial.println(" is not attached");
#endif
  for (int count = 0; count < numSweeps; count++) { //The head sweeps left and right twice
    static int sweep = 10;                         //initialize sweep angle to 10 degrees
    while (sweep < MAX_ANGLE) {
      myServo[servo].write(sweep);
      sweep = sweep + 1;
      delay(10); //wait
    }
    while (sweep > MIN_ANGLE) {
      myServo[servo].write(sweep);
      sweep = sweep - 1;
      delay(10); //wait
    }
  } //End for loop
  //} //End if
}//End function

@zoolandermicro 

Here is a slightly modified version which creates the head as a separate entity from the array. It also includes a few mods to reduce the code and I've added some pre-processor Serial prints for debugging.

I am curious to see if part (or maybe all) of the problem is memory being overwritten.

I just read throught your code. Looks excellent. It tests, in the setup function, if the head servo is attached to pin 14. I had tried creating a separate servo object before without success. I will try your code when I get home from work tonight. Thanks @will . 

@will line 20, the comment should be 2 through 13 I think

@zoolandermicro 

I just Googled the kit and it only seems to implement the legs, with the head being fixed in position. I had assumed (a nasty habit) that there was original working code that used 13 servos.

Google also seems to indicate that 12 is about the max number of servos that Servo.h can handle. There is supposedly another library that lets you use any pin as a servo driver but I haven't investigated it.

To move the head, you could just use a DC motor and controller or even stepper motor (which might allow more precise control over the direction).

Posted by: @zander

@will line 20, the comment should be 2 through 13 I think

Yep, it sure should 🙂

Hi 

Just read a quick summary of your posts re problem connecting a 13th servo.

I had a look at this library write up on the arduino site and it looks like 12 is the maximum unless your board is an arduino Due.

This is an extract:

Servo

Device Control

Allows Arduino boards to control a variety of servo motors.
This library can control a great number of servos. It makes careful use of timers: the library can control 12 servos using only 1 timer. On the Arduino Due you can control up to 60 servos.

Is this your issue?

Ron Bentley

@will @zander @ronbentley1 I verified the code that Will provided. Avrdude reported:

Sketch uses 4020 bytes (12%) of program storage space. Maximum is 32256 bytes.
Global variables use 379 bytes (18%) of dynamic memory, leaving 1669 bytes for local variables. Maximum is 2048 bytes.

The code useses very little program or dynamic memory. Uploaded the code and the Hexapod legs worked through their routene, but the head servo still didn't move. Output to the serial monitor:

myHead servo assigned pin is 14 which is attached
In botHead_Sweep the head servo is attached

The serial output confirms that the servo controling the head is attached, and the action of the Hexabot indicates that the code in function botHead_Sweep() is running. There is a pause before the leg movement resumes. The first 12 servos are seized by timer 0. The next twelve servos would be seized by timer 1 (inference from the note in the servo.h file). Timer 1 may not be running at the correct frequency to produce the proper PWM output to run the servo. I will reference a book I have that explains how to set the timer frequeicies. Setting the proper frequency of timer 1 may resolve this issue (I can only hope). Thanks for the code example. I like the efficientcy of your code changes.

Hi again,

Ive just looked at the servo library files and your use of 13 servos should be okay as the library object should claim 2 x 16 bit timers on instantiation. This would mean that with these two times 24 servos should be supportable.

It's a bit suspicious that 12 is working, these supported by the first 16 bit time but the 13th isn't, which should be on the second timer

In case there is a boundary value condition error in the library try increasing your number of servos to 14, to see if you get the 13th working.

If so, then there is likely to be a boundary condition error?

Ron Bentley

Posted by: @ronbentley1

On the Arduino Due you can control up to 60 servos.

The Adeept Pixie board has a Mega328P chip like the Arduino Uno board. I think the Due uses a Mega2560 chip.