Wirelessly Control Multiple Servos in Arduino Using a RF24 Bluetooth Connecter

The goal of this Instructable is to teach how to wirelessly control multiple servos using a potentiometer and a RF24 Bluetooth device.

This Instructable can be used for any Arduino project that requires you to remotely operate a system, such as RC vehicles, robotic arms, or any device that can’t have exposed wiring.

Included in this instructable:

1. Parts list, wiring diagram, and commented code for both the transmitter and receiver.
2. Guide for wiring both modules
3. Guide for installing code to both arduino’s
4. Links to all parts required

Note: This instructable is made with the assumption that you have downloaded and operated arduino IDE before, can read wiring diagrams, and are familiar with the basics of arduino’s. If you have never worked with arduino’s before, please consult the official guide here.

You will need a surplus of both M-F and M-M wires

Transmitter:

1. Arduino Uno
2. Breadboard
3. Potentiometer (sliding or spin type) x2
4. RF24 Bluetooth module
5. Micro-USB Cable

Receiver:

1. Arduino Uno
2. Breadboard
3. Mini Servo x2
4. RF24 Bluetooth module
5. Micro-USB Cable

Transmitter:

This is our transmitter, it uses 2 potentiometers and a Bluetooth module, it runs on Arduino uno.

The notation for the wiring on the Bluetooth module will be x,y with x being if its column and y being the row its in. wire 1,1 to the 3.3v port of your Arduino. 2,1 goes to ground on the breadboard. 1,2 goes to I pin 8. 2,2 goes to l pin 9. 1,3 goes to pin 11. 2,3 goes to ping 13. 2,4 goes to pin 12.

Then wire your potentiometers, we used sliding potentiometers but TinkerCad only has the circular ones. Wire the first pin to ground on each, and wire the 3rd pin to power, then put the 2nd pin of each one to input A0 and A1 respectively.

Wire the breadboard so the 5v supply from the Arduino powers the + side of the board and the ground goes to the - side.

Receiver:

This is the diagram for the receiver, both the servos are connected to the same ground and power (5V). The Wiring for the RF24 Module is Identical to the Transmitter before hand.

All code found here is a modified version of https://www.robotroom.com/BipolarHBridge.html check the link out if you want a more in-depth explanation on how RC works for Arduino!

This is a breakdown of all the code you will need for the Transmitter, full code found at the bottom of this step, along with a direct download link for IDE.

Include Required Libraries

#include <SPI.h>

#include <nRF24L01.h>

#include <RF24.h>

Ensure the RF24 library is added to your Arduino IDE:

Initialize Bluetooth Communication

RF24 radio(9, 8); // CE, CSN

const byte address[6] = "07190";

byte Array[2];

Set the address to a unique value and ensure it matches on both transmitter and receiver.

Define Potentiometer Variables

int read0;

int read1;

These will store readings from the potentiometers.

Set Up Bluetooth

void setup() {

// set up bluetooth

radio.begin();

radio.openWritingPipe(address);

radio.setPALevel(RF24_PA_MIN);

radio.stopListening();

Serial.begin(9600);

}

This configures the bluetooth in writing mode.

Read and Scale Potentiometer Values

void loop() {

// get potentiometer readings

read0 = analogRead(A0);

read1 = analogRead(A1);

// constrain to (0 - 180) for servos

Array[0] = map(constrain(read0, 0, 1023), 0, 1023, 0, 180);

Array[1] = map(constrain(read1, 0, 1023), 0, 1023, 0, 180);

// send data through bluetooth

radio.write(&Array, sizeof(Array));

Serial.println("sending");

delay(15);

}

This ensures the potentiometer values are properly constrained and mapped for servo use.

A sliding potentiometer must be scaled from 1023 to 180 and a spin potentiometer must be scaled from 255 to 180.

If using a spin potentiometer change the constrain line to:

Array[0] = map(constrain(read0, 0, 255), 0, 255, 0, 180);

Array[1] = map(constrain(read1, 0, 255), 0, 255, 0, 180);

Sliding Potentiometer: Spin Potentiometer:

Full Code:

This is the Breakdown for the receiver code, Download link found at the bottom as well

Include Required Libraries

#include <SPI.h>

#include <nRF24L01.h>

#include <RF24.h>

#include <Servo.h>

Make sure to add the RF24 and Servo libraries to your Arduino IDE:

Initialize Servos and Bluetooth Communication

Servo myServo1;

Servo myServo2;

RF24 radio(9, 8); // CE, CSN

const byte address[6] = "07190";

The address must match the one in the transmitter code.

Set Up Servos and Bluetooth:

void setup() {

// set up servos

myServo1.attach(3);

myServo2.attach(6);

myServo1.write(90);

myServo2.write(90);

radio.begin();

radio.openReadingPipe(0, address);

radio.setPALevel(RF24_PA_MIN);

radio.startListening();

Serial.begin(9600);

}

Setting servos to 90 degrees at startup helps with troubleshooting.

Receive Data and Control Servos

void loop() {

if (radio.available()) {

byte Array[2];

radio.read(&Array, sizeof(Array));

// print potentiometer values (for troubleshooting)

Serial.print(Array[0]);

Serial.println();

Serial.print(Array[1]);

Serial.println();

// set servo position to potentiometer values

myServo1.write(Array[0]);

myServo2.write(Array[1]);

delay(15);

}

This ensures the servos move according to the received potentiometer values.

Full Code: