How to control 6 servo motors with an Arduino Mega board?

Question

I am trying to make autonomous hexapod with an Arduino Mega board. I have followed tripod mechanism of hexapod movement. First I could control simultaneously legs (0, 2, 4) and (1, 3, 5) separately but whenever I tried to combine both i.e control 6 legs at a time I could not see any movement in the hexapod. Even in the IDE I am not getting any error.

I have connected the legs (0 to 5) to signal pins (2 to 7) respectively. I have connected a common +5v voltage and common ground voltage to individual legs using a breadboard. Can anyone give me a proper solution to overcome this issue and further would like to know how to control multiple servos and source code for it?

Here is my Arduino source code for controlling 6 servo motors.

#include <Servo.h>
Servo myservo[6]; 
int f=0;// create servo object to control a servo
//[0] -tibia , [1] -femur , [2] -coxa motors
void setup() {
 myservo[0].attach(2);
 myservo[1].attach(3);
 myservo[2].attach(4);
 myservo[3].attach(5);
 myservo[4].attach(6);
 myservo[5].attach(7);
}
void loop() {
 //alternatively making hexapod stand at its place
 //f is just flag variable to make it stop
 if(f==0) {
 myservo[0].write(130);
 myservo[2].write(130);
 myservo[4].write(90);
 myservo[1].write(130);
 myservo[3].write(90);
 myservo[5].write(0);
 f=1;
 }
}

Note the values that are added above are calculated separately for individual legs to mount legs on ground.

• Edgar Bonet: If you set your code to control 6 servos, does it work when you only connect 3 servos? If it does, then the problem may just be that your power supply is not strong enough to power 6 servos.
• Likhith R: @EdgarBonet thank you it works fine when it connected to external power supply
• Ecko: I want to control 18 servos and based on your code I would add in 14 more servo objects. Is there a final code that you already finished with the 6 servos?

Answer 1

The Arduino Mega can handle at most 40mA on the I/O pins, and 200mA on the 5V/GND pins. Six servos will draw far more current than the max of 200mA. You could try hooking up the servo power to a separate power source and the data pins to the Arduino. Hope this helps!

Answer 2

in the odd case that you are actually powering your (small?) servo's directly through the arduino : you'll need an external power source for your servo's.