Phone Controlled Robot Car using Wi-Fi Module

Remotely controlled car - IoT based project using Wi-Fi Module and MIT App Inventor with intuitive control. A step-by-step guide!

Sep 24, 2021

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Devices & Components

Arduino Uno Rev3

Li-Polymer Battery, 150mAh

DC Motor, 12 V

NodeMCU ESP8266 Breakout Board

Dual H-Bridge motor drivers L298

Jumper wires (generic)

Hardware & Tools

Mastech MS8217 Autorange Digital Multimeter

Multitool, Screwdriver

Software & Tools

Arduino IDE

MIT App Inventor 2

Project description

Code

Arduino Uno Code

arduino

Code for receiving incoming data from NodeMCU and giving input to the motor drivers to vary the speed and direction of spin of motors.

1#include <Wire.h>
2
3//motors
4int motor1pin1 = 2;
5int motor1pin2  = 3;
6int motor2pin1 = 4;
7int motor2pin2 = 5;
8
9int speed9 = 40;
10int  speed10 = 40;
11
12int slider;
13int valx;
14int valy;
15
16void setup() {
17  Wire.begin(8);                /* join i2c bus with address 8 */
18 Wire.onReceive(receiveEvent);  /* register receive event */
19 Wire.onRequest(requestEvent); /* register request  event */
20 Serial.begin(9600);           /* start serial for debug */
21
22  pinMode(motor1pin1, OUTPUT);
23  pinMode(motor1pin2, OUTPUT);
24  pinMode(motor2pin1,  OUTPUT);
25  pinMode(motor2pin2, OUTPUT);
26
27  pinMode(9, OUTPUT);
28  pinMode(10,  OUTPUT);
29
30  analogWrite(9,speed9); //left
31  analogWrite(10, speed10);//Right
32
33  //anticlockwise
34  digitalWrite(motor1pin1, HIGH); //right motor going front
35  digitalWrite(motor1pin2, LOW); //right motor going front
36  digitalWrite(motor2pin1,  LOW); //left motor going front
37  digitalWrite(motor2pin2, HIGH); //left motor  going front
38
39  /*temporary setup code*/
40  analogWrite(9, 60);
41  analogWrite(10,  60);
42}
43
44void loop() {
45
46}
47
48// function that executes whenever  data is received from master
49void receiveEvent(int howMany) {
50 while (0 <Wire.available())  {
51    byte low = Wire.read();
52    byte high = Wire.read();
53    int val  = word(high, low);
54    
55    
56    if(val>200 && val<=400){
57      //Serial.print("Y:  ");
58      valy = 400 - val;
59      //Serial.println(valy);
60      if(valy<=100){
61        digitalWrite(motor1pin1, HIGH); //right motor going front
62        digitalWrite(motor1pin2,  LOW); //right motor going front
63        digitalWrite(motor2pin1, LOW); //left  motor going front
64        digitalWrite(motor2pin2, HIGH); //left motor going  front
65        Serial.print("Moving Forward");
66       
67      }
68      else  if(valy>100){
69        digitalWrite(motor1pin1, LOW); //right motor going front
70        digitalWrite(motor1pin2, HIGH); //right motor going front
71        digitalWrite(motor2pin1,  HIGH); //left motor going front
72        digitalWrite(motor2pin2, LOW); //left  motor going front
73        Serial.print("Moving Backward");
74      }
75    }
76    if(val>1000){
77      //Serial.print("Speed: ");
78      slider = val -  1000;
79      speed10 = slider/5;
80      speed9 = slider/5;
81      //Serial.println(slider);
82      analogWrite(10, speed10);//right
83      analogWrite(9, speed9);//left
84      Serial.print("Left speed: ");
85      Serial.println(speed9);
86      Serial.print("Right  speed: ");
87      Serial.println(speed10);
88    }
89    if(val<=200){
90      //Serial.print("X: ");
91      valx = 200-val;
92      //Serial.println(valx);
93      if(valx<100){
94        speed9 = speed9 - ((100-valx)/10);
95        speed10  = speed10 + ((100-valx)/10);
96        analogWrite(9, speed9);
97        analogWrite(10,  speed10);
98        if(speed9<0){
99          speed9 = 0;
100          speed10  = 100;
101          analogWrite(9, speed9);
102          analogWrite(10, speed10);
103        }
104        Serial.print("Left speed: ");
105        Serial.println(speed9);
106        Serial.print("Right speed: ");
107        Serial.println(speed10);
108      }
109      else if(valx>100){
110        speed9 = speed9 + ((valx-100)/10);
111        speed10 = speed10 - ((valx-100)/10);
112        analogWrite(9, speed9);
113        analogWrite(10, speed10);
114        if(speed10<0){
115          speed9  = 100;
116          speed10 = 0;
117          analogWrite(9, speed9);
118          analogWrite(10,  speed10);
119        }
120        Serial.print("Left speed: ");
121        Serial.println(speed9);
122        Serial.print("Right speed: ");
123        Serial.println(speed10);
124      }
125      else if(valx==100){
126        speed9 = 40;
127        speed10  = 40;
128        analogWrite(9, speed9);
129        analogWrite(10, speed10);
130        Serial.print("Left speed: ");
131        Serial.println(speed9);
132        Serial.print("Right  speed: ");
133        Serial.println(speed10);
134      }
135    }
136 Serial.println();             /* to newline */
137}
138}
139

#include <Wire.h>

//motors
int motor1pin1 = 2;
int motor1pin2  = 3;
int motor2pin1 = 4;
int motor2pin2 = 5;

int speed9 = 40;
int  speed10 = 40;

int slider;
int valx;
int valy;

void setup() {
  Wire.begin(8);                /* join i2c bus with address 8 */
 Wire.onReceive(receiveEvent);  /* register receive event */
 Wire.onRequest(requestEvent); /* register request  event */
 Serial.begin(9600);           /* start serial for debug */

  pinMode(motor1pin1, OUTPUT);
  pinMode(motor1pin2, OUTPUT);
  pinMode(motor2pin1,  OUTPUT);
  pinMode(motor2pin2, OUTPUT);

  pinMode(9, OUTPUT);
  pinMode(10,  OUTPUT);

  analogWrite(9,speed9); //left
  analogWrite(10, speed10);//Right

  //anticlockwise
  digitalWrite(motor1pin1, HIGH); //right motor going front
  digitalWrite(motor1pin2, LOW); //right motor going front
  digitalWrite(motor2pin1,  LOW); //left motor going front
  digitalWrite(motor2pin2, HIGH); //left motor  going front

  /*temporary setup code*/
  analogWrite(9, 60);
  analogWrite(10,  60);
}

void loop() {

}

// function that executes whenever  data is received from master
void receiveEvent(int howMany) {
 while (0 <Wire.available())  {
    byte low = Wire.read();
    byte high = Wire.read();
    int val  = word(high, low);
    
    
    if(val>200 && val<=400){
      //Serial.print("Y:  ");
      valy = 400 - val;
      //Serial.println(valy);
      if(valy<=100){
        digitalWrite(motor1pin1, HIGH); //right motor going front
        digitalWrite(motor1pin2,  LOW); //right motor going front
        digitalWrite(motor2pin1, LOW); //left  motor going front
        digitalWrite(motor2pin2, HIGH); //left motor going  front
        Serial.print("Moving Forward");
       
      }
      else  if(valy>100){
        digitalWrite(motor1pin1, LOW); //right motor going front
        digitalWrite(motor1pin2, HIGH); //right motor going front
        digitalWrite(motor2pin1,  HIGH); //left motor going front
        digitalWrite(motor2pin2, LOW); //left  motor going front
        Serial.print("Moving Backward");
      }
    }
    if(val>1000){
      //Serial.print("Speed: ");
      slider = val -  1000;
      speed10 = slider/5;
      speed9 = slider/5;
      //Serial.println(slider);
      analogWrite(10, speed10);//right
      analogWrite(9, speed9);//left
      Serial.print("Left speed: ");
      Serial.println(speed9);
      Serial.print("Right  speed: ");
      Serial.println(speed10);
    }
    if(val<=200){
      //Serial.print("X: ");
      valx = 200-val;
      //Serial.println(valx);
      if(valx<100){
        speed9 = speed9 - ((100-valx)/10);
        speed10  = speed10 + ((100-valx)/10);
        analogWrite(9, speed9);
        analogWrite(10,  speed10);
        if(speed9<0){
          speed9 = 0;
          speed10  = 100;
          analogWrite(9, speed9);
          analogWrite(10, speed10);
        }
        Serial.print("Left speed: ");
        Serial.println(speed9);
        Serial.print("Right speed: ");
        Serial.println(speed10);
      }
      else if(valx>100){
        speed9 = speed9 + ((valx-100)/10);
        speed10 = speed10 - ((valx-100)/10);
        analogWrite(9, speed9);
        analogWrite(10, speed10);
        if(speed10<0){
          speed9  = 100;
          speed10 = 0;
          analogWrite(9, speed9);
          analogWrite(10,  speed10);
        }
        Serial.print("Left speed: ");
        Serial.println(speed9);
        Serial.print("Right speed: ");
        Serial.println(speed10);
      }
      else if(valx==100){
        speed9 = 40;
        speed10  = 40;
        analogWrite(9, speed9);
        analogWrite(10, speed10);
        Serial.print("Left speed: ");
        Serial.println(speed9);
        Serial.print("Right  speed: ");
        Serial.println(speed10);
      }
    }
 Serial.println();             /* to newline */
}
}

NodeMCU Code

arduino

Code for taking input data from your Joystick application on the phone and sending the data to Arduino via I2C communication protocol.

1#include <ESP8266WiFi.h>
2#include <WiFiClient.h>
3#include <Wire.h>
4
5const  char* ssid = "Wi-Fi name";
6const char* password = "password";
7
8WiFiServer  server(80);
9
10void setup() {
11  Serial.begin(115200);
12  delay(10);
13
14  Wire.begin(D1, D2); 
15  
16  Serial.println();
17  Serial.print("Connecting  to ");
18  Serial.print(ssid);
19
20  WiFi.begin(ssid, password);
21
22  while(WiFi.status()  != WL_CONNECTED){
23    delay(500);
24    Serial.print(".");
25  }
26  Serial.println("");
27  Serial.println("WiFi connected");
28
29  server.begin(); 
30  Serial.println("Server  started");
31
32  Serial.println(WiFi.localIP());
33}
34
35void loop() {
36  WiFiClient client = server.available();
37  if(!client){
38    return;
39  }
40
41  Serial.println("New Client");
42  while(!client.available()){
43    delay(1);
44  }
45
46  String req = client.readStringUntil('\r');
47  req.replace("+",  " ");          // Spaces without +
48  req.replace(" HTTP/1.1", "");   //  this delete HTTP/1.1
49  req.replace("GET /", "");   
50  int val = req.toInt();
51
52  byte buffer[10];
53  buffer[0] = lowByte(val);
54  buffer[1] = highByte(val);
55
56  Serial.println(val);
57  Wire.beginTransmission(8);
58  Wire.write(buffer, 2);
59  Wire.endTransmission();
60  
61  
62  client.flush();
63
64}

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <Wire.h>

const  char* ssid = "Wi-Fi name";
const char* password = "password";

WiFiServer  server(80);

void setup() {
  Serial.begin(115200);
  delay(10);

  Wire.begin(D1, D2); 
  
  Serial.println();
  Serial.print("Connecting  to ");
  Serial.print(ssid);

  WiFi.begin(ssid, password);

  while(WiFi.status()  != WL_CONNECTED){
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  server.begin(); 
  Serial.println("Server  started");

  Serial.println(WiFi.localIP());
}

void loop() {
  WiFiClient client = server.available();
  if(!client){
    return;
  }

  Serial.println("New Client");
  while(!client.available()){
    delay(1);
  }

  String req = client.readStringUntil('\r');
  req.replace("+",  " ");          // Spaces without +
  req.replace(" HTTP/1.1", "");   //  this delete HTTP/1.1
  req.replace("GET /", "");   
  int val = req.toInt();

  byte buffer[10];
  buffer[0] = lowByte(val);
  buffer[1] = highByte(val);

  Serial.println(val);
  Wire.beginTransmission(8);
  Wire.write(buffer, 2);
  Wire.endTransmission();
  
  
  client.flush();

}

Remote_Controll_Joystick.aia

java

You can open this file by going to https://appinventor.mit.edu/. Download the .aia file and then import project on the App Inventor.

1inary file (no preview

inary file (no preview

NodeMCU Code

arduino

Code for taking input data from your Joystick application on the phone and sending the data to Arduino via I2C communication protocol.

1#include <ESP8266WiFi.h>
2#include <WiFiClient.h>
3#include <Wire.h>
4
5const   char* ssid = "Wi-Fi name";
6const char* password = "password";
7
8WiFiServer   server(80);
9
10void setup() {
11  Serial.begin(115200);
12  delay(10);
13
14   Wire.begin(D1, D2); 
15  
16  Serial.println();
17  Serial.print("Connecting   to ");
18  Serial.print(ssid);
19
20  WiFi.begin(ssid, password);
21
22  while(WiFi.status()   != WL_CONNECTED){
23    delay(500);
24    Serial.print(".");
25  }
26  Serial.println("");
27   Serial.println("WiFi connected");
28
29  server.begin(); 
30  Serial.println("Server   started");
31
32  Serial.println(WiFi.localIP());
33}
34
35void loop() {
36   WiFiClient client = server.available();
37  if(!client){
38    return;
39  }
40
41   Serial.println("New Client");
42  while(!client.available()){
43    delay(1);
44   }
45
46  String req = client.readStringUntil('\
');
47  req.replace("+",   " ");          // Spaces without +
48  req.replace(" HTTP/1.1", "");   //   this delete HTTP/1.1
49  req.replace("GET /", "");   
50  int val = req.toInt();
51
52   byte buffer[10];
53  buffer[0] = lowByte(val);
54  buffer[1] = highByte(val);
55
56   Serial.println(val);
57  Wire.beginTransmission(8);
58  Wire.write(buffer, 2);
59   Wire.endTransmission();
60  
61  
62  client.flush();
63
64}

#include <ESP8266WiFi.h>
#include <WiFiClient.h>
#include <Wire.h>

const   char* ssid = "Wi-Fi name";
const char* password = "password";

WiFiServer   server(80);

void setup() {
  Serial.begin(115200);
  delay(10);

   Wire.begin(D1, D2); 
  
  Serial.println();
  Serial.print("Connecting   to ");
  Serial.print(ssid);

  WiFi.begin(ssid, password);

  while(WiFi.status()   != WL_CONNECTED){
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
   Serial.println("WiFi connected");

  server.begin(); 
  Serial.println("Server   started");

  Serial.println(WiFi.localIP());
}

void loop() {
   WiFiClient client = server.available();
  if(!client){
    return;
  }

   Serial.println("New Client");
  while(!client.available()){
    delay(1);
   }

  String req = client.readStringUntil('\
');
  req.replace("+",   " ");          // Spaces without +
  req.replace(" HTTP/1.1", "");   //   this delete HTTP/1.1
  req.replace("GET /", "");   
  int val = req.toInt();

   byte buffer[10];
  buffer[0] = lowByte(val);
  buffer[1] = highByte(val);

   Serial.println(val);
  Wire.beginTransmission(8);
  Wire.write(buffer, 2);
   Wire.endTransmission();
  
  
  client.flush();

}

Remote_Controll_Joystick.aia

java

You can open this file by going to https://appinventor.mit.edu/. Download the .aia file and then import project on the App Inventor.

1inary file (no preview

inary file (no preview

Downloadable files

Interfacing L298n motor driver with Arduino and Motors

We direct the power to the Arduino via the L298n motor driver.

Interfacing L298n motor driver with Arduino and Motors

Interfacing NodeMCU with Arduino

To power the NodeMCU, just connect the 3V3 pin on the Wi-Fi module to 3.3V port on Arduino.

Interfacing NodeMCU with Arduino

Speed and Direction Control Circuit

Interfacing L298n motor driver with Arduino and Motors

We direct the power to the Arduino via the L298n motor driver.

Interfacing L298n motor driver with Arduino and Motors

Interfacing NodeMCU with Arduino

To power the NodeMCU, just connect the 3V3 pin on the Wi-Fi module to 3.3V port on Arduino.

Interfacing NodeMCU with Arduino

Speed and Direction Control Circuit

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