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Robot Arm using PCA9685 PWM Servo Driver and SG-90 Servo Motor

Table of Contents ▼

01 — Overview
02 — Hardware and Software Components
03 — Application Discussion
04 — Hardware Setup
05 — Software Setup
06 — Code
07 — Code Breakdown
08 — Testing and Calibration
09 — System Demonstration
10 — Conclusion
11 — References
12 — Project Authors

01 Overview

This project aims to produce a robot arm capable of performing simple tasks, such as placing objects. Developed using Arduino IDE, the robot arm utilizes the teach & repeat pattern to carry out tasks. To enable object placement, the development team coded a specific pattern. Moreover, the code can be modified, allowing the robot arm to perform different tasks as required.

Project Use Case

- This project is useful for simple, repetitive tasks. It is especially useful in factories because it has a lot of repetitive tasks due to long production lines of the same product.

02 Hardware and Software Components

Prepare all the required components and materials before starting. This checklist only includes the names, models, and versions needed for the project.

Hardware Components

Component	Description
Arduino UNO Board	Servo Motor processing microcontroller
PCA9685 PWM Driver	Connection between Arduino UNO and Servo Motors
SG-90 Servo motor	Movement capability of the robot arm
Acrylic Components	Robot arm components
Jumper Wires	Hardware connections
External 5V Supply	S]Power supply for the components

Software Tools

Software	Version / Details
Arduino IDE	2.3.9
Adafruit PWM Servo Driver	2.4.0

Project Files

File	Description
Robot_arm.ino	Main Arduino sketch for the Robot Arm movement sequence

03 Application Discussion

Here is what each component does and why it is part of this project.

Arduino UNO Board

The Arduino UNO development board serves as the primary controller for the servo motors. It controls the movement of each motor.

PCA9685 PWM Driver

The PWM Driver acts as the main connector between the Arduino UNO board and the SG-90 servo motors. It allows the Arduino UNO board to control multiple motors using 2 communication pins.

SG-90 Servo Motor

The servo motor allows movement for each segment of the robot arm.

Acrylic Components

These are like puzzle pieces that connect and form the robot arm.

Jumper Wires

These provide the necessary connections for the robot arm to work.

04 Hardware Setup

Wire the components by following the circuit diagram. You can also use the tables below as a guide for the connections.

PCA9685 to Arduino Connections

pca9685 Pin	Arduino Pin	Description
SDA	A4	Data highway
SCL	A5	Clock pulse
VCC	VIN	Power Supply
GND	GND	Ground Connection

For each SG-90 Servo Motor to PCA9685 PWM Driver just follow the color coding for each wire. (Yellow: Digital Signal, Red: VCC, Brown: GND)

Assembly Instructions

Assemble the Robot Arm (might take a while).
Connect the SDA pin of PCA9685 to A4 of Arduino.
Connect the SCL pin of PCA9685 to A5 of Arduino.
Connect the VCC and GND of PCA9685 to VIN and GND, respectively, on the Arduino Board
Connect the 4 motors to I/O pins 4,5,6,7 of the PCA9685 PWM Driver
Connect the middle positive and negative sides of the PCA9685 PWM Driver to the 5V and GND pins, respectively, on the Arduino Board.
Upload the Robot_arm sketch file into the Arduino UNO Board by connecting the Arduino Board to the PC.
Once the code has been uploaded, disconnect the Arduino from the PC and use an external 5V supply to power the Arduino by plugging it into the DC Jacket of the Arduino board.

05 Software Setup

Follow these steps in order. Do not skip the file replacement steps — they are required for this board to work correctly.

Step 1 — Install Arduino IDE

Open a web browser and go to the official Arduino website.
Download the latest version of the Arduino IDE compatible with your operating system.
Run the installer after the download is complete.
Follow the installation instructions and wait for the setup to finish.
Open the Arduino IDE after installation.
Connect the Arduino UNO Board device to the computer using USB cables.

Step 2 — Install Adafruit PWM Servo Driver Library

Open the Arduino IDE.
Go to Tools > Manage Libraries.
Search for AdaFruit PWM Servo Driver Library and click Install.

Setting	Value
Board	Arduino UNO

Step 3 — Upload Robot Arm Sketch

Open the Robot Arm Sketch file in the Arduino IDE.
Follow all assembly instructions
Select the Arduino UNO Board under Tools > Board.
Select the correct COM port under Tools > Port.
Click the Verify button to compile the code and check for errors.
After successful verification, click the Upload button.
Wait for the upload process to complete.
NOTE: ENSURE THAT THE ROBOT ARM HAS A SOLID BASE TO AVOID IT FROM FALLING OVER

06 Code

Copy the file below and do not modify the code unless you understand what each part does — the Code Breakdown section explains it.

Main Sketch for Robot Arm — Robot_arm.ino

Arduino / C++

#define /*Robot arm control with Arduino
   https://srituhobby.com
*/

#include 
#include 

Adafruit_PWMServoDriver srituhobby = Adafruit_PWMServoDriver();

#define servo1 4
#define servo2 5
// #define servo3 6
#define servo4 7


void setup() {
  Serial.begin(9600);
  srituhobby.begin();
  srituhobby.setPWMFreq(60);
  srituhobby.setPWM(servo1, 0, 400);
  srituhobby.setPWM(servo2, 0, 150);
  // srituhobby.setPWM(servo3, 0, 260);
  srituhobby.setPWM(servo4, 0, 150);
  delay(3000);
}

void loop() {

  for (int S1value = 400; S1value >= 150; S1value--) {
    srituhobby.setPWM(servo1, 0, S1value);
    delay(10);
  }
  delay(2000);
  for (int S2value = 150; S2value <= 400; S2value++) {
    srituhobby.setPWM(servo2, 0, S2value);
    delay(10);
  }
  delay(1000);

    for (int S4value = 150; S4value <= 225; S4value++) {
    srituhobby.setPWM(servo4, 0, S4value);
    delay(10);
  }
  delay(3000);
    for (int S4value = 225; S4value >= 150; S4value--) {
    srituhobby.setPWM(servo4, 0, S4value);
    delay(10);
  }
  delay(1000);

    for (int S2value = 400; S2value >= 150; S2value--) {
    srituhobby.setPWM(servo2, 0, S2value);
    delay(10);
  }
  delay(1000);
    


  // for (int S3value = 300; S3value <= 380; S3value++) {
  //   srituhobby.setPWM(servo3, 0, S3value);
  //   delay(10);
  // }

  // // for (int S4value = 410; S4value <= 510; S4value++) {
  // //   srituhobby.setPWM(servo4, 0, S4value);
  // //   delay(10);
  // // }
  // ////////////////////////
  // // delay(2000);
  // // for (int S4value = 510; S4value > 410; S4value--) {
  // //   srituhobby.setPWM(servo4, 0, S4value);
  // //   delay(10);
  // // }

  // for (int S3value = 380; S3value > 300; S3value--) {
  //   srituhobby.setPWM(servo3, 0, S3value);
  //   delay(10);
  // }

  // for (int S2value = 380; S2value > 150; S2value--) {
  //   srituhobby.setPWM(servo2, 0, S2value);
  //   delay(10);
  // }

  for (int S1value = 150; S1value < 400; S1value++) {
    srituhobby.setPWM(servo1, 0, S1value);
    delay(10);
  }
  delay(3000);
    for (int S2value = 150; S2value <= 400; S2value++) {
    srituhobby.setPWM(servo2, 0, S2value);
    delay(10);
  }
  
    for (int S4value = 150; S4value <= 225; S4value++) {
    srituhobby.setPWM(servo4, 0, S4value);
    delay(10);
  }
  delay(1000);
    for (int S2value = 400; S2value >= 150; S2value--) {
    srituhobby.setPWM(servo2, 0, S2value);
    delay(10);
  }
  delay(1000);
    for (int S4value = 225; S4value >= 150; S4value--) {
    srituhobby.setPWM(servo4, 0, S4value);
    delay(10);
  }
  // //////////////////////
  // for (int S2value = 150; S2value <= 380; S2value++) {
  //   srituhobby.setPWM(servo2, 0, S2value);
  //   delay(10);
  // }

  // for (int S3value = 300; S3value <= 380; S3value++) {
  //   srituhobby.setPWM(servo3, 0, S3value);
  //   delay(10);
  // }


  // ///////////////////
  // for (int S3value = 380; S3value > 300; S3value--) {
  //   srituhobby.setPWM(servo3, 0, S3value);
  //   delay(10);
  // }

  // for (int S2value = 380; S2value > 150; S2value--) {
  //   srituhobby.setPWM(servo2, 0, S2value);
  //   delay(10);
  // }

  // for (int S1value = 450; S1value > 330; S1value--) {
  //   srituhobby.setPWM(servo1, 0, S1value);
  //   delay(10);
  // }
  // delay(1000);
}

}

07 Code Breakdown

This explains the function of each part of the code to help in understanding how it works.

Libraries (Adafruit PWM Servo Driver Library)

Library	Purpose
Adafruit_PWMServoDriver.h	This library is used to communicate with the servo motors using the Arduino IDE

Key Functions (Robot Arm Sketch File)

setup()

This part of the code handles the initialization of the initial position of the robot arm.

loop()

This handles the sequence of movement that the robot arm does. (Note: The angle 0 degrees is equal to 150, and the angle 180 degrees is equal to 600 in the code)

Code Components in RFID Reader Sketch File

Component / Function	Purpose
beep(int duration)	Controls the buzzer sound and LED indicator whenever an RFID card is scanned.

General Program Workflow (RFID Reader Sketch File)

The setup() initializes the initial positions of the robot arm
The loop() repeats a movement sequence coded into the microcontroller
Picks up an object and places it in another location, then repeats until disconnected.

08 Testing and Calibration

After uploading, check the following to ensure the system is functioning properly.

Robot Arm Test

This test checks if the robot arm can perform its intended function without the motors jamming or malfunctioning.

09 System Demonstration

Video Demonstration

10 Conclusion

The project demonstrated the process of building and controlling a robotic arm using the PCA9685 PWM driver. It showed how the PCA9685 simplifies the control of multiple servo motors by providing stable and precise PWM signals through I²C communication. Overall, the project highlights the practical application of electronics, programming, and robotics in creating a functional robotic arm capable of performing controlled movements.

Possible Improvements and Future Enhancements

Add joystick control for more flexibility

11 References

Youtube - How to assemble and control a 4 DOF robot mechanical arm kit with Arduino | Step by step

12 Project Authors

Matthew Vincent Bacaling
Japhet Prince Pesic

Tags: 16 channel 12-bit pwm servo shield, Arduino ide, Arduino uno, C++, Pca9685, Pwm, Robotic arm claw kit 4dof, Servo motor, Sg90

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Robot Arm using PCA9685 PWM Servo Driver and SG-90 Servo Motor

Robot Arm using PCA9685 PWM Servo Driver and SG-90 Servo Motor

01 Overview

Project Use Case

02 Hardware and Software Components

Hardware Components

Software Tools

Project Files

03 Application Discussion

Arduino UNO Board

PCA9685 PWM Driver

SG-90 Servo Motor

Acrylic Components

Jumper Wires

04 Hardware Setup

PCA9685 to Arduino Connections

Assembly Instructions

05 Software Setup

Step 1 — Install Arduino IDE

Step 2 — Install Adafruit PWM Servo Driver Library

Step 3 — Upload Robot Arm Sketch

06 Code

Main Sketch for Robot Arm — Robot_arm.ino

07 Code Breakdown

Libraries (Adafruit PWM Servo Driver Library)

Key Functions (Robot Arm Sketch File)

setup()

loop()

Code Components in RFID Reader Sketch File

General Program Workflow (RFID Reader Sketch File)

08 Testing and Calibration

Robot Arm Test

09 System Demonstration

10 Conclusion

Possible Improvements and Future Enhancements

11 References

12 Project Authors

Robot Arm using PCA9685 PWM Servo Driver and SG-90 Servo Motor

01 Overview

Project Use Case

02 Hardware and Software Components

Hardware Components

Software Tools

Project Files

03 Application Discussion

Arduino UNO Board

PCA9685 PWM Driver

SG-90 Servo Motor

Acrylic Components

Jumper Wires

04 Hardware Setup

PCA9685 to Arduino Connections

Assembly Instructions

05 Software Setup

Step 1 — Install Arduino IDE

Step 2 — Install Adafruit PWM Servo Driver Library

Step 3 — Upload Robot Arm Sketch

06 Code

Main Sketch for Robot Arm — Robot_arm.ino

07 Code Breakdown

Libraries (Adafruit PWM Servo Driver Library)

Key Functions (Robot Arm Sketch File)

setup()

loop()

Code Components in RFID Reader Sketch File

General Program Workflow (RFID Reader Sketch File)

08 Testing and Calibration

Robot Arm Test

09 System Demonstration

10 Conclusion

Possible Improvements and Future Enhancements

11 References

12 Project Authors

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