Please Help Programming nRF24L01 Remote Bot

Other Hardware Robotics
1

Hello!

I am working on modifying an Elegoo Smart Car to be controlled by a 2.4ghz remote control for a STEM camp I'm doing this summer. I've gotten it to allow me to control the servo but can't seem to work out the code to control the motors. I've included my current code and some links to pics below.

I could really use some help with the code and I know the students would appreciate it as well.

Thanks!

Kevin

Transmitter Code:

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
RF24 radio(9, 10); // CE, CSN
const byte address[6] = "00001";

int x_key = A0;                                               
int y_key = A1;
int k_key = A2;                                               
int z_key = A3;                                           
int x_pos;
int y_pos;
int k_pos;
int z_pos;

const int frontButton = 6; //pressing button moves toy car forward
const int backButton = 5;  //pressing button moves toy car backward
const int leftButton = 4;  //pressing button moves toy car to left
const int rightButton = 3; //pressing button moves toy car to right


void setup() {
  radio.begin();
  radio.openWritingPipe(address);
  radio.setPALevel(RF24_PA_MIN);
  radio.stopListening();

  pinMode (x_key, INPUT) ;                     
  pinMode (y_key, INPUT) ;
  pinMode (k_key, INPUT) ;                     
  pinMode (y_key, INPUT) ;    
}

void loop() {
  x_pos = analogRead (x_key) ;  
  y_pos = analogRead (y_key) ;   
  radio.write(&x_pos, sizeof(x_pos));
  k_pos = analogRead (k_key) ;  
  z_pos = analogRead (z_key) ;   
  radio.write(&k_pos, sizeof(z_pos));
  delay(100);
}

Receiver Code:

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

const int IN1 = 7;
const int IN2 = 8;
const int IN3 = 9;
const int IN4 = 11;

Servo servo;
RF24 radio(A0, A1); // CE, CSN
const byte address[6] = "00001";
int servo_pin = 3;

void setup() {
      pinMode(IN1,OUTPUT);
      pinMode(IN2,OUTPUT);
      pinMode(IN3,OUTPUT);
      pinMode(IN4,OUTPUT);
      Serial.begin(9600);
      
      radio.begin();
      Serial.println("checking if chip connected");
      Serial.print("check-");

 
      servo.attach (servo_pin ) ; 
      radio.openReadingPipe(0, address);
      radio.setPALevel(RF24_PA_MIN);
      radio.startListening();
}

void loop() {

  if (radio.available()) {
    int k_pos ;
    radio.read(&k_pos, sizeof(k_pos));
    Serial.println(k_pos);
    k_pos = map(k_pos, 0, 1023, 0, 180);
    if (k_pos>400 && k_pos<600)
    {
      
    }
    else{
    servo.write (k_pos) ;
    }
  }

     if (radio.available()) {
            int message[4];
            radio.read(&message, sizeof(message));
            int i;
            for (i = 0; i < 4; i = i + 1) {
                  Serial.print(message[i]);
            }
            Serial.println();
            int sum = message[0]+message[1]+message[2]+message[3];
            if (sum==4) {
                  //stop
                  digitalWrite(IN1,LOW);
                  digitalWrite(IN2,LOW);
                  digitalWrite(IN3,LOW);
                  digitalWrite(IN4,LOW);
                  Serial.println("LLLL");                  
            }
            if (sum==3) {
                  if (message[0]==0 && message[1]==1 && message[2]==1 && message[3]==1) {
                        //move forward
                        digitalWrite(IN1,HIGH);
                        digitalWrite(IN2,LOW);
                        digitalWrite(IN3,LOW);
                        digitalWrite(IN4,HIGH);
                        Serial.println("HLLH");
                  }
                  if (message[0]==1 && message[1]==0 && message[2]==1 && message[3]==1) {
                        //move backward
                        digitalWrite(IN1,LOW);
                        digitalWrite(IN2,HIGH);
                        digitalWrite(IN3,HIGH);
                        digitalWrite(IN4,LOW);
                        Serial.println("LHHL");
                  }
                  if (message[0]==1 && message[1]==1 && message[2]==0 && message[3]==1) {
                        //move forward
                        digitalWrite(IN1,LOW);
                        digitalWrite(IN2,LOW);
                        digitalWrite(IN3,LOW);
                        digitalWrite(IN4,HIGH);
                        Serial.println("LLLH");
                  }
                  if (message[0]==1 && message[1]==1 && message[2]==1 && message[3]==0) {
                        //move left
                        digitalWrite(IN1,HIGH);
                        digitalWrite(IN2,LOW);
                        digitalWrite(IN3,LOW);
                        digitalWrite(IN4,LOW);
                        Serial.println("HLLL");
                  }
            }
            if (sum<=2) {
                  //stop
                  digitalWrite(IN1,LOW);
                  digitalWrite(IN2,LOW);
                  digitalWrite(IN3,LOW);
                  digitalWrite(IN4,LOW);
                  Serial.println("LLLL");
            }
      }
}

Some Pics:

4032×3024 3.46 MB

3413×2943 2.58 MB

4032×3024 2.58 MB

Servo_Plus_Motor_Remote_Test.ino (1.13 KB)

Servo_plus_Motor_Test.ino (3.32 KB)

2

You will get faster and more help if you post the code as described in the how to use this forum-please read sticky. Members do not like to download code. It is a pain to get the downloaded code into the IDE (or other editor) for evaluation.

Images likewise. To post images, follow this guide.

3

Thanks for the heads up. I updated my post in response.

4 
 x_pos = analogRead (x_key) ;  
  y_pos = analogRead (y_key) ;  
  radio.write(&x_pos, sizeof(x_pos));
  k_pos = analogRead (k_key) ;  
  z_pos = analogRead (z_key) ;  
  radio.write(&k_pos, sizeof(z_pos));

Here you are writing 2 packets. And you are only sending x and k. I am not sure if, when the receiver gets the packets, that the receiver actually reads them both. I would combine the x, y, z, and k into one packet (int array) and send all at once.

&k_pos, sizeof(z_pos))

k_pos and z_pos are both ints sot it probably doesn't matter, but it looks funny to send k with z size.

5

Thanks for your help. Some additional info...

I'm trying to have the left joystick control the drive (forward, back, left, right) and the right stick to turn the servo on top manually (I'd like to replace the rangefinder with other perifrials).