I am trying to make a Bluetooth controlled 4WD robot. i was following a tutorial i found online (https://howtomechatronics.com/tutorials/arduino/arduino-robot-car-wireless-control-using-hc-05-bluetooth-nrf24l01-and-hc-12-transceiver-modules/). After successfully connecting my 2 HC 05 Bluetooth module i used the script from the tutorial and modified it slightly so it would work for my set up. The code for the robot:
//Code for Slave
#define enA 9
#define in1 8
#define in2 7
#define enB 10
#define in3 6
#define in4 5
int xAxis, yAxis;
unsigned int x = 0;
unsigned int y = 0;
int motorSpeedA = 0;
int motorSpeedB = 0;
void setup() {
pinMode(enA, OUTPUT);
pinMode(enB, OUTPUT);
pinMode(in1, OUTPUT);
pinMode(in2, OUTPUT);
pinMode(in3, OUTPUT);
pinMode(in4, OUTPUT);
Serial.begin(9600); // Default communication rate of the Bluetooth module
}
void loop() {
// Default value - no movement when the Joystick stays in the center
x = 510 / 4;
y = 510 / 4;
// Read the incoming data from the Joystick, or the master Bluetooth device
while (Serial.available() >= 2) {
x = Serial.read();
Serial.print("X: ");
Serial.println(x);
delay(10);
y = Serial.read();
Serial.print("Y: ");
Serial.println(y);
}
delay(10);
// Convert back the 0 - 255 range to 0 - 1023, suitable for motor control code below
xAxis = x*4;
yAxis = y*4;
// Y-axis used for forward and backward control
if (yAxis < 470) {
backMov;
// Convert the declining Y-axis readings for going backward from 470 to 0 into 0 to 255 value for the PWM signal for increasing the motor speed
motorSpeedA = map(yAxis, 470, 0, 0, 255);
motorSpeedB = map(yAxis, 470, 0, 0, 255);
}
else if (yAxis > 550) {
fowardMov;
// Convert the increasing Y-axis readings for going forward from 550 to 1023 into 0 to 255 value for the PWM signal for increasing the motor speed
motorSpeedA = map(yAxis, 550, 1023, 0, 255);
motorSpeedB = map(yAxis, 550, 1023, 0, 255);
}
// If joystick stays in middle the motors are not moving
else {
motorSpeedA = 0;
motorSpeedB = 0;
}
// X-axis used for left and right control
if (xAxis < 470) {
// Convert the declining X-axis readings from 470 to 0 into increasing 0 to 255 value
int xMapped = map(xAxis, 470, 0, 0, 255);
// Move to left - decrease left motor speed, increase right motor speed
motorSpeedA = motorSpeedA + xMapped;
motorSpeedB = motorSpeedB - xMapped;
// Confine the range from 0 to 255
if (motorSpeedA > 255) {
motorSpeedA = 255;
}
if (motorSpeedB < 0) {
motorSpeedB = 0;
}
}
if (xAxis > 550) {
// Convert the increasing X-axis readings from 550 to 1023 into 0 to 255 value
int xMapped = map(xAxis, 550, 1023, 0, 255);
// Move right - decrease right motor speed, increase left motor speed
motorSpeedA = motorSpeedA - xMapped;
motorSpeedB = motorSpeedB + xMapped;
// Confine the range from 0 to 255
if (motorSpeedA < 0) {
motorSpeedA = 0;
}
if (motorSpeedB > 255) {
motorSpeedB = 255;
}
}
// Prevent buzzing at low speeds (Adjust according to your motors. My motors couldn't start moving if PWM value was below value of 70)
if (motorSpeedA < 70) {
motorSpeedA = 0;
}
if (motorSpeedB < 70) {
motorSpeedB = 0;
}
analogWrite(enA, motorSpeedA); // Send PWM signal to motor A
analogWrite(enB, motorSpeedB); // Send PWM signal to motor B
}
void fowardMov(){
digitalWrite(in2,HIGH);
digitalWrite(in4,HIGH);
digitalWrite(in1, LOW);
digitalWrite(in3, LOW);
}
void backMov(){
digitalWrite(in1,HIGH);
digitalWrite(in3,HIGH);
digitalWrite(in2, LOW);
digitalWrite(in4, LOW);
}
The code for the Controller:
#define Xaxis A0
#define Yaxis A1
void setup() {
// put your setup code here, to run once:
Serial.begin(9600);
}
void loop() {
// put your main code here, to run repeatedly:
Serial.write(analogRead(Xaxis)/4);
Serial.write(analogRead(Yaxis)/4);
delay(20);
}
After uploading the code i tried to move it but it wasn't working so i put print statements to see the value of X and Y. initially it didn't work so i swapped the Bluetooth modules i had and reconnected them. i also changed this line.
while (Serial.available() >= 2)
To this
if (Serial.available() > 0)
i started to receive values from the master to the slave but i noticed the values were the same for x and y so i searched for another tutorial on the internet and found this (https://create.arduino.cc/projecthub/andriy-baranov/arduino-4wd-rc-car-639953?ref=similar&ref_id=18369&offset=3) reading his code i wondered how did the slave work. According to the official Arduino documentation Serial.read() does not take in any arguments but i still tried it and it didn't work. I decided to retry the code from the first tutorial i checked this time it looked like it was working so i tried moving the joystick and the serial monitor printed correct values for both at first then it swaps their values then freezes. How can i stop it from freezing and swapping the values? Also why doesn't the while loop run forever isn't the amount of data in the serial buffer always higher than 2? Thank you.