Are you fascinated by the world of remote-controlled cars and eager to delve into the code that brings them to life? Controlling an RC car with Bluetooth using Arduino is a fantastic project for hobbyists and coding enthusiasts alike. This guide will explore a fundamental Arduino code example for Bluetooth-controlled RC cars and address a common issue you might encounter: beeping sounds from your motor driver.
Here’s a basic Arduino code snippet designed to control an RC car via Bluetooth commands. This code is compatible with an app that communicates with your Arduino board through a Bluetooth module.
/* Code Name: Arduino Bluetooth Control Car Code URI: https://carcodescanner.store Author: carcodescanner.store Description: This program is used to control a robot using a app that communicates with Arduino through a bluetooth module. App URI: https://bit.ly/2BlMAea Version: 1.0 License: Remixing or Changing this Thing is allowed. Commercial use is not allowed. */
#define in1 4 //L298n Motor Driver pins.
#define in2 5
#define in3 6
#define in4 7
#define LED 13
int command; //Int to store app command state.
int Speed = 204; // 0 - 255.
int Speedsec;
int buttonState = 0;
int lastButtonState = 0;
int Turnradius = 0; //Set the radius of a turn, 0 - 255
//Note:the robot will malfunction if this is higher than int Speed.
int brakeTime = 45;
int brkonoff = 1; //1 for the electronic braking system, 0 for normal.
void setup() {
pinMode(in1, OUTPUT);
pinMode(in2, OUTPUT);
pinMode(in3, OUTPUT);
pinMode(in4, OUTPUT);
pinMode(LED, OUTPUT); //Set the LED pin.
Serial.begin(9600); //Set the baud rate to your Bluetooth module.
}
void loop() {
if (Serial.available() > 0) {
command = Serial.read();
Stop(); //Initialize with motors stoped.
switch (command) {
case 'F':
forward();
break;
case 'B':
back();
break;
case 'L':
left();
break;
case 'R':
right();
break;
case 'G':
forwardleft();
break;
case 'I':
forwardright();
break;
case 'H':
backleft();
break;
case 'J':
backright();
break;
case '0':
Speed = 100;
break;
case '1':
Speed = 140;
break;
case '2':
Speed = 153;
break;
case '3':
Speed = 165;
break;
case '4':
Speed = 178;
break;
case '5':
Speed = 191;
break;
case '6':
Speed = 204;
break;
case '7':
Speed = 216;
break;
case '8':
Speed = 229;
break;
case '9':
Speed = 242;
break;
case 'q':
Speed = 255;
break;
}
Speedsec = Turnradius;
if (brkonoff == 1) {
brakeOn();
} else {
brakeOff();
}
}
}
void forward() {
analogWrite(in1, Speed);
analogWrite(in3, Speed);
}
void back() {
analogWrite(in2, Speed);
analogWrite(in4, Speed);
}
void left() {
analogWrite(in3, Speed);
analogWrite(in2, Speed);
}
void right() {
analogWrite(in4, Speed);
analogWrite(in1, Speed);
}
void forwardleft() {
analogWrite(in1, Speedsec);
analogWrite(in3, Speed);
}
void forwardright() {
analogWrite(in1, Speed);
analogWrite(in3, Speedsec);
}
void backright() {
analogWrite(in2, Speed);
analogWrite(in4, Speedsec);
}
void backleft() {
analogWrite(in2, Speedsec);
analogWrite(in4, Speed);
}
void Stop() {
analogWrite(in1, 0);
analogWrite(in2, 0);
analogWrite(in3, 0);
analogWrite(in4, 0);
}
void brakeOn() { //Here's the future use: an electronic braking system!
// read the pushbutton input pin:
buttonState = command;
// compare the buttonState to its previous state
if (buttonState != lastButtonState) {
// if the state has changed, increment the counter
if (buttonState == 'S') {
if (lastButtonState != buttonState) {
digitalWrite(in1, HIGH);
digitalWrite(in2, HIGH);
digitalWrite(in3, HIGH);
digitalWrite(in4, HIGH);
delay(brakeTime);
Stop();
}
}
// save the current state as the last state,
//for next time through the loop
lastButtonState = buttonState;
}
}
void brakeOff() {
}Code Explanation:
This code is designed to be used with an L298N motor driver and a Bluetooth module connected to your Arduino. Let’s break down the key sections:
- Motor Control Pins:
#define in1 4, etc., These lines assign digital pins on your Arduino to control the L298N motor driver. Ensure these pin numbers match your wiring. - Speed and Turning:
int Speed = 204;sets the default motor speed. You can adjust this value (0-255) to change the car’s speed.Turnradiusis intended for adjusting turning radius, though in this basic code, it’s not fully utilized for nuanced turning control. - Bluetooth Communication:
Serial.begin(9600);initializes serial communication at 9600 baud rate, which is common for Bluetooth modules like HC-05 or HC-06. - Command Handling: The
loop()function continuously checks for incoming serial data from your Bluetooth module. When a command is received (e.g., ‘F’ for forward, ‘B’ for backward, ‘L’ for left, ‘R’ for right), the code executes the corresponding motor function (forward(),back(),left(),right(), etc.). - Speed Adjustment: Commands ‘0’ through ‘9’ and ‘q’ are used to change the motor speed, offering different speed levels.
- Braking (Electronic Braking System): The
brakeOn()andbrakeOff()functions are included, withbrakeOn()attempting to implement an electronic braking system. However, in the current code, the braking logic is tied to a command ‘S’ and might need further refinement for practical use.
Troubleshooting Beeping Sounds from L298N Motor Driver
A user reported experiencing a beeping sound from the L298N motor driver when using this code and supplying power through a laptop via Arduino. This beeping is often an indicator of insufficient power.
Reason for Beeping: Power Supply Issues
When you power motors through the Arduino’s USB connection to your laptop, you are limited by the power that the USB port can provide. Motors, especially when starting or under load, can draw more current than a USB port can reliably deliver. This lack of sufficient power can cause the L298N driver to malfunction and potentially produce a beeping sound.
Solutions to Resolve Beeping:
-
External Power Supply: The most effective solution is to use an external power supply specifically for your motors and L298N driver.
- Voltage and Amperage: Check the voltage requirements of your motors and the L298N driver. Typically, a 9V or 12V battery pack or power adapter is suitable. Ensure the power supply can provide enough amperage (current) for your motors. Motors often have a stall current significantly higher than their running current, so choose a power supply with sufficient headroom.
- Separate Power: Connect the external power supply directly to the L298N motor driver’s power input terminals, not through the Arduino. The Arduino should be powered separately (either through USB or another power source if needed for your Bluetooth module). Important: Ensure the grounds of the Arduino and the L298N driver are connected for proper signal communication.
-
Check Power Requirements:
- Motor Specifications: Review the specifications of your RC car motors to understand their voltage and current requirements.
- L298N Datasheet: Consult the datasheet of your L298N motor driver to understand its operating voltage range and current handling capabilities.
-
Reduce Motor Load (Temporarily for Testing): If you want to test with USB power briefly, try reducing the load on the motors. For example, lift the RC car wheels off the ground so the motors are not working against friction or gravity. If the beeping stops or reduces significantly, it further points to a power supply issue when the motors are under load.
In Summary
Coding a Bluetooth-controlled RC car with Arduino is an exciting and educational project. The provided code offers a starting point for basic control. If you encounter beeping sounds from your motor driver, especially when powering through USB, prioritize using an adequate external power supply for your motors. This will ensure reliable operation and prevent potential damage to your components. Happy coding and driving!
