Waiting for data from transmitter using URF24L01 with URF adapter

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1

I was trying to make the hand gesture to the RC car by following:
Hand Gesture Controlled Car Using Arduino​:fist_right::red_car: (youtube. com)
And I have a problem with receiving data from the transmitter. I can see it sends data from the transmitter code on a serial monitor, and I tested the NRF24L01+ module connected from my receiver on a serial monitor. But I couldn't receive data from my transmitter. Can someone help?

2

I can't follow the text, make a block diagram, please. Are you using TWO NRF24L01 devices?

3

No. I am using nano for transmitter and mega2560 for receiver. I just figured out how to receive data and was able to make the Rc car to move, but it moves slowly.
Reveiver code here:

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

#define SIGNAL_TIMEOUT 500  // Signal timeout in milliseconds
#define MAX_MOTOR_SPEED 1023 // Maximum motor speed

const uint64_t pipeIn = 0xF9E8F0F0E1LL;
RF24 radio(8, 9); // CE, CSN pins

unsigned long lastRecvTime = 0;

struct PacketData
{
  byte xAxisValue;
  byte yAxisValue;
} receiverData;

// Motor pins
int enableRightMotor = 5;
int rightMotorPin1 = 3; // Change to match your setup
int rightMotorPin2 = 2; // Change to match your setup
int enableLeftMotor = 6;
int leftMotorPin1 = 7; // Change to match your setup
int leftMotorPin2 = 4; // Change to match your setup

void setup()
{
  pinMode(enableRightMotor, OUTPUT);
  pinMode(rightMotorPin1, OUTPUT);
  pinMode(rightMotorPin2, OUTPUT);
  pinMode(enableLeftMotor, OUTPUT);
  pinMode(leftMotorPin1, OUTPUT);
  pinMode(leftMotorPin2, OUTPUT);

  rotateMotor(0, 0);

  radio.begin();
  radio.setDataRate(RF24_250KBPS);
  radio.openReadingPipe(1, pipeIn);
  radio.startListening(); // Start the radio receiver

#ifdef PRINT_DEBUG
  Serial.begin(115200);
#endif
}

void loop()
{
  int rightMotorSpeed = 0;
  int leftMotorSpeed = 0;

  // Check if RF is connected and packet is available
  if (radio.isChipConnected() && radio.available())
  {
    radio.read(&receiverData, sizeof(PacketData));

    // Map joystick values directly to motor speeds
    rightMotorSpeed = map(receiverData.yAxisValue, 0, 254, -MAX_MOTOR_SPEED, MAX_MOTOR_SPEED);
    leftMotorSpeed = map(receiverData.yAxisValue, 0, 254, -MAX_MOTOR_SPEED, MAX_MOTOR_SPEED);

    // Invert motor speeds for backward movement
    if (rightMotorSpeed < 0)
    {
      rightMotorSpeed = -rightMotorSpeed;
      leftMotorSpeed = -leftMotorSpeed;
    }

    // Apply constraints to motor speeds
    rightMotorSpeed = constrain(rightMotorSpeed, -MAX_MOTOR_SPEED, MAX_MOTOR_SPEED);
    leftMotorSpeed = constrain(leftMotorSpeed, -MAX_MOTOR_SPEED, MAX_MOTOR_SPEED);

    rotateMotor(rightMotorSpeed, leftMotorSpeed);
    lastRecvTime = millis();

#ifdef PRINT_DEBUG
    Serial.println(receiverData.xAxisValue);
    Serial.println(receiverData.yAxisValue);
#endif
  }
  else
  {
    // Signal lost. Reset the motor to stop
    unsigned long now = millis();
    if (now - lastRecvTime > SIGNAL_TIMEOUT)
    {
      rotateMotor(0, 0);
    }
  }
}

void rotateMotor(int rightMotorSpeed, int leftMotorSpeed)
{
  // Control right motor
  if (rightMotorSpeed >= 0)
  {
    digitalWrite(rightMotorPin1, HIGH);
    digitalWrite(rightMotorPin2, LOW);
  }
  else
  {
    digitalWrite(rightMotorPin1, LOW);
    digitalWrite(rightMotorPin2, HIGH);
  }

  // Control left motor
  if (leftMotorSpeed >= 0)
  {
    digitalWrite(leftMotorPin1, HIGH);
    digitalWrite(leftMotorPin2, LOW);
  }
  else
  {
    digitalWrite(leftMotorPin1, LOW);
    digitalWrite(leftMotorPin2, HIGH);
  }

  // Set motor speeds
  analogWrite(enableRightMotor, abs(rightMotorSpeed));
  analogWrite(enableLeftMotor, abs(leftMotorSpeed));
}

and transmitter code here:

//#include "I2Cdev.h"
#include "MPU6050_6Axis_MotionApps20.h"

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>

#define PRINT_DEBUG   //Uncomment this line if you want to print the MPU6050 initialization information on serial monitor

const uint64_t pipeOut = 0xF9E8F0F0E1LL;
RF24 radio(8, 9); // select CE,CSN pin

struct PacketData 
{
  byte xAxisValue;
  byte yAxisValue;
} data;

MPU6050 mpu;
bool dmpReady = false;
uint8_t devStatus;
uint16_t packetSize;
uint8_t fifoBuffer[64];
Quaternion q;
VectorFloat gravity;
float ypr[3];

void setupRadioTransmitter()
{
  radio.begin();
  radio.setDataRate(RF24_250KBPS);
  radio.openWritingPipe(pipeOut);
  radio.stopListening(); //start the radio communication for Transmitter  

  data.xAxisValue = 127; // Center
  data.yAxisValue = 127; // Center 
}

void setupMPU()
{
  #if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
      Wire.begin();
      Wire.setClock(400000);
  #elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
      Fastwire::setup(400, true);
  #endif

  #ifdef PRINT_DEBUG
    Serial.begin(115200);
    while (!Serial);
    Serial.println(F("Initializing I2C devices..."));
  #endif
  
  mpu.initialize();

  #ifdef PRINT_DEBUG  
    Serial.println(F("Testing device connections..."));
    Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));
    Serial.println(F("\nSend any character to begin DMP programming and demo: "));
    while (Serial.available() && Serial.read());
    while (!Serial.available());
    while (Serial.available() && Serial.read());
    Serial.println(F("Initializing DMP..."));
  #endif
  
  devStatus = mpu.dmpInitialize();
  
  if (devStatus == 0) 
  {
      mpu.CalibrateAccel(6);
      mpu.CalibrateGyro(6);
      
      #ifdef PRINT_DEBUG      
        mpu.PrintActiveOffsets();
        Serial.println(F("Enabling DMP..."));
      #endif
      mpu.setDMPEnabled(true);
  
      #ifdef PRINT_DEBUG      
        Serial.println(F("DMP ready! Waiting for first interrupt..."));
      #endif
      dmpReady = true;
  
      packetSize = mpu.dmpGetFIFOPacketSize();
  } 
  else 
  {
      #ifdef PRINT_DEBUG       
        Serial.print(F("DMP Initialization failed (code "));
        Serial.print(devStatus);
        Serial.println(F(")"));
      #endif
  }
}

void setup() 
{
  setupRadioTransmitter();   
  setupMPU();
}

void loop() 
{
  if (!dmpReady) return;

  if (mpu.dmpGetCurrentFIFOPacket(fifoBuffer)) 
  {  
    mpu.dmpGetQuaternion(&q, fifoBuffer);
    mpu.dmpGetGravity(&gravity, &q);
    mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);

    int xAxisValue = constrain(ypr[2] * 180/M_PI, -90, 90);
    int yAxisValue = constrain(ypr[1] * 180/M_PI, -90, 90);
    data.xAxisValue = map(xAxisValue, -90, 90, 0, 254); 
    data.yAxisValue = map(yAxisValue, -90, 90, 254, 0);

    radio.write(&data, sizeof(PacketData));

    #ifdef PRINT_DEBUG  
      Serial.print("x:");
      Serial.println(xAxisValue);  
      Serial.print("y:");
      Serial.println(yAxisValue);        
    #endif
  }
}
4

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