Hi all,
Trying to use nRF24L01 modules to transmit the x/y positions of a joystick to drive 2 DC motors through an L298N driver. (Using 2 UNOs) (Joystick moves in y-direction = both motors forwards/backwards, x-direction = one forwards one backwards).
The code for driving the motors works perfectly fine when the joystick is connected to the same UNO as the motors, however I am having trouble now I have introduced another UNO and the nRF24l01 modules.
When wired up, both motors constantly turn in one direction at full speed, regardless of the position of the joystick on the other UNO.
I have read that a 10µF capacitor across VCC/GND can help, but not sure if it is the code?
Cheers!
Transmitter Code:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(7, 8); // CE, CSN
const byte address[6] = "00001";
char xyData[32] = "";
String xAxis, yAxis;
void setup() {
Serial.begin(9600);
radio.begin();
radio.openWritingPipe(address);
radio.setPALevel(RF24_PA_MIN);
radio.stopListening();
}
void loop() {
xAxis = analogRead(A0); // Read Joysticks X-axis
yAxis = analogRead(A1); // Read Joysticks Y-axis
// X value
xAxis.toCharArray(xyData, 5); // Put the String (X Value) into a character array
radio.write(&xyData, sizeof(xyData)); // Send the array data (X value) to the other NRF24L01 modile
// Y value
yAxis.toCharArray(xyData, 5);
radio.write(&xyData, sizeof(xyData));
delay(20);
}
Receiver Code:
#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#define enA 9
#define in1 3
#define in2 4
#define enB 10
#define in3 5
#define in4 6
RF24 radio(7, 8); // CE, CSN
const byte address[6] = "00001";
char receivedData[32] = "";
int xAxis, yAxis;
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);
radio.begin();
radio.openReadingPipe(0, address);
radio.setPALevel(RF24_PA_MIN);
radio.startListening();
}
void loop() {
if (radio.available()) { // If the NRF240L01 module received data
radio.read(&receivedData, sizeof(receivedData)); // Read the data and put it into character array
xAxis = atoi(&receivedData[0]); // Convert the data from the character array (received X value) into integer
delay(10);
radio.read(&receivedData, sizeof(receivedData));
yAxis = atoi(&receivedData[0]);
delay(10);
}
if (yAxis < 470 || yAxis > 550) {
// Y-axis used for forward and backward control
if (yAxis < 470) {
// Set Motor A Backward
digitalWrite(in1, HIGH);
digitalWrite(in2, LOW);
// Set Motor B Backward
digitalWrite(in3, HIGH);
digitalWrite(in4, LOW);
// 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) {
// Set Motor A forward
digitalWrite(in1, LOW);
digitalWrite(in2, HIGH);
// Set Motor B forward
digitalWrite(in3, LOW);
digitalWrite(in4, HIGH);
// 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;
}
}
else if (yAxis > 470 && yAxis < 550) {
// X-axis used for left and right control
if (xAxis < 470) {
// Set Motor A Backward
digitalWrite(in1, HIGH);
digitalWrite(in2, LOW);
// Set Motor B Forward
digitalWrite(in3, LOW);
digitalWrite(in4, HIGH);
// Convert the declining X-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(xAxis, 470, 0, 0, 255);
motorSpeedB = map(xAxis, 470, 0, 0, 255);
}
else if (xAxis > 550) {
// Set Motor A forward
digitalWrite(in1, LOW);
digitalWrite(in2, HIGH);
// Set Motor B Backward
digitalWrite(in3, HIGH);
digitalWrite(in4, LOW);
// Convert the increasing X-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(xAxis, 550, 1023, 0, 255);
motorSpeedB = map(xAxis, 550, 1023, 0, 255);
}
// If joystick stays in middle the motors are not moving
else {
motorSpeedA = 0;
motorSpeedB = 0;
}
}
else {
motorSpeedA = 0;
motorSpeedB = 0;
}
// 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 < 50) {
motorSpeedA = 0;
}
if (motorSpeedB < 50) {
motorSpeedB = 0;
}
analogWrite(enA, motorSpeedA); // Send PWM signal to motor A
analogWrite(enB, motorSpeedB); // Send PWM signal to motor B
}
