Arduino [Modbus] RC Car with Web Camera and Remote Browser Control

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Here is my project with remote control of different devices with Arduino Nano

Video tutorial on how to configure remote control of devices connected to an Arduino Nano using a gamepad and a real-time video stream.

A humorous video featuring an RC car that uses an Arduino Nano.

brain-nervous
brain-nervous960×1280 107 KB

mounting1
mounting11280×960 73.1 KB

mounting3
mounting31280×960 179 KB

The Arduino code used in the first video.

#include <ModbusRTUSlave.h>
#include <Servo.h>

// ================== PIN MAPPING ==================
const uint8_t digitalPins[] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}; // Digital ping
const bool pwmPins[] = {false, true, false, true, true, false, false, true, true, true, false, false};  // PWM
const uint8_t digitalInPins[] = {A0, A1, A2, A3};              // digital
const uint8_t analogPins[] = {A0, A1, A2, A3, A4, A5, A6, A7};     // analog

Servo servos[11];
uint16_t servosDefault[] = {1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500};

// ================== STATE ARRAYS ==================
#define NUM_COILS       sizeof(digitalPins)/sizeof(digitalPins[0])
#define NUM_HOLDINGS    sizeof(digitalPins)/sizeof(digitalPins[0])
#define NUM_DISCRETE    sizeof(digitalInPins)/sizeof(digitalInPins[0])
#define NUM_INPUTS      sizeof(analogPins)/sizeof(analogPins[0])

bool coils[NUM_COILS] = {0};
uint16_t holdingRegs[NUM_HOLDINGS] = {0};
bool discreteInputs[NUM_DISCRETE] = {0};
uint16_t inputRegs[NUM_INPUTS] = {0};

// ================== MODBUS ==================
ModbusRTUSlave modbus(Serial, -1, -1);

unsigned long lastCommandTime = 0;
const unsigned long COMMAND_TIMEOUT = 1000;

// ================== SETUP ==================
void setup() {
  pinMode(13, OUTPUT);
  digitalWrite(13, LOW);
  delay(500);
  digitalWrite(13, HIGH);

  Serial.begin(9600);

  for(uint8_t i=0; i<NUM_COILS; i++){
    if(pwmPins[i]) {
      servos[i].attach(digitalPins[i]);
      servos[i].writeMicroseconds(servosDefault[i]);
      holdingRegs[i] = servosDefault[i];
    } else {
      pinMode(digitalPins[i], OUTPUT);
      digitalWrite(digitalPins[i], LOW);
    }
  }

  for(uint8_t i=0;i<NUM_DISCRETE;i++){
    pinMode(digitalInPins[i], INPUT_PULLUP);
  }

  modbus.configureCoils(coils, NUM_COILS);
  modbus.configureHoldingRegisters(holdingRegs, NUM_HOLDINGS);
  modbus.configureDiscreteInputs(discreteInputs, NUM_DISCRETE);
  modbus.configureInputRegisters(inputRegs, NUM_INPUTS);

  // Modbus slave (ID=1, baud 9600, SERIAL_8N1)
  modbus.begin(1, 9600, SERIAL_8N1);
}

// ================== LOOP ==================
void loop() {
  if(true) {
    modbus.poll();

//========================================
// ===== DETECT COMMAND CHANGES =====
  if(false) {
    bool commandReceived = false;

    for (uint8_t i = 0; i < NUM_HOLDINGS; i++) {
      static uint16_t prev[NUM_HOLDINGS] = {0};
      if (holdingRegs[i] != prev[i]) {
        prev[i] = holdingRegs[i];
        commandReceived = true;
      }
    }

    for (uint8_t i = 0; i < NUM_COILS; i++) {
      static bool prevC[NUM_COILS] = {0};
      if (coils[i] != prevC[i]) {
        prevC[i] = coils[i];
        commandReceived = true;
      }
    }

    if (commandReceived) {
      lastCommandTime = millis();
    }

    // ===== TIMEOUT FAILSAFE =====
    if (millis() - lastCommandTime > COMMAND_TIMEOUT) {
      for (uint8_t i = 0; i < NUM_HOLDINGS; i++) {
        if (pwmPins[i]) {
          holdingRegs[i] = servosDefault[i];
        }
      }
    }
  }
//========================================
    for(uint8_t i=0;i<NUM_COILS;i++){
      if(pwmPins[i]){
        servos[i].writeMicroseconds(holdingRegs[i]);
      } else {
        digitalWrite(digitalPins[i], coils[i] ? HIGH : LOW);
      }
    }

    for(uint8_t i=0;i<NUM_DISCRETE;i++){
      discreteInputs[i] = digitalRead(digitalInPins[i]);
    }

    for(uint8_t i=0;i<NUM_INPUTS;i++){
      inputRegs[i] = analogRead(analogPins[i]);
    }
  }
}

The Arduino code used in the second video.

#include <ModbusRTUSlave.h>
#include <Servo.h>

// ================== PIN MAPPING ==================
const uint8_t digitalPins[] = {2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}; // Digital ping
const bool pwmPins[] = {false, true, false, true, true, false, false, true, true, true, false, false};  // PWM
const float pwmSmooth[] = {1.0, 1.0,   1.0,  1.0,  1.0,   1.0,   1.0,  0.1,  1.0,  0.1,   1.0,   1.0};  // smoothing
const uint8_t digitalInPins[] = {A0, A1, A2, A3};              // digital
const uint8_t analogPins[] = {A0, A1, A2, A3, A4, A5, A6, A7};     // analog

Servo servos[11];
uint16_t servosDefault[] = {1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500};
uint16_t servosShift[] = {0, 0, 0, 0, 0, 0, 0, 15, 0, 0, 0, 0};

// ================== STATE ARRAYS ==================
#define NUM_COILS       sizeof(digitalPins)/sizeof(digitalPins[0])
#define NUM_HOLDINGS    sizeof(digitalPins)/sizeof(digitalPins[0])
#define NUM_DISCRETE    sizeof(digitalInPins)/sizeof(digitalInPins[0])
#define NUM_INPUTS      sizeof(analogPins)/sizeof(analogPins[0])

bool coils[NUM_COILS] = {0};
uint16_t holdingRegs[NUM_HOLDINGS] = {0};
bool discreteInputs[NUM_DISCRETE] = {0};
uint16_t inputRegs[NUM_INPUTS] = {0};

uint16_t servoFiltered[NUM_HOLDINGS] = {0};

// ================== MODBUS ==================
ModbusRTUSlave modbus(Serial, -1, -1); // Serial, DE/RE pins (-1 if no RS-485)

unsigned long lastCommandTime = 0;
const unsigned long COMMAND_TIMEOUT = 1000;

// ================== SETUP ==================
void setup() {
    pinMode(13, OUTPUT);
    digitalWrite(13, LOW);
    delay(500);
    digitalWrite(13, HIGH);

    Serial.begin(9600);

    for(uint8_t i=0; i < NUM_COILS; i++){
        if(pwmPins[i]) {
            servos[i].attach(digitalPins[i]);
            servos[i].writeMicroseconds(servosDefault[i] + servosShift[i]);
            holdingRegs[i] = servosDefault[i];
        } else {
            pinMode(digitalPins[i], OUTPUT);
            digitalWrite(digitalPins[i], LOW);
        }
    }

    for(uint8_t i = 0; i < NUM_DISCRETE; i++){
        pinMode(digitalInPins[i], INPUT_PULLUP);
    }

    modbus.configureCoils(coils, NUM_COILS);
    modbus.configureHoldingRegisters(holdingRegs, NUM_HOLDINGS);
    modbus.configureDiscreteInputs(discreteInputs, NUM_DISCRETE);
    modbus.configureInputRegisters(inputRegs, NUM_INPUTS);

    // Modbus slave (ID=1, baud 9600, SERIAL_8N1)
    modbus.begin(1, 9600, SERIAL_8N1);
}

// ================== LOOP ==================
void loop() {
    modbus.poll();

    //========================================
    // ===== DETECT COMMAND CHANGES =====
    if(false) {
        bool commandReceived = false;

        for (uint8_t i = 0; i < NUM_HOLDINGS; i++) {
            static uint16_t prev[NUM_HOLDINGS] = {0};
            if (holdingRegs[i] != prev[i]) {
                prev[i] = holdingRegs[i];
                commandReceived = true;
            }
        }

        for (uint8_t i = 0; i < NUM_COILS; i++) {
            static bool prevC[NUM_COILS] = {0};
            if (coils[i] != prevC[i]) {
                prevC[i] = coils[i];
                commandReceived = true;
            }
        }

        if (commandReceived) {
            lastCommandTime = millis();
        }

        // ===== TIMEOUT FAILSAFE =====
        if (millis() - lastCommandTime > COMMAND_TIMEOUT) {
            for (uint8_t i = 0; i < NUM_HOLDINGS; i++) {
                if (pwmPins[i]) {
                    holdingRegs[i] = servosDefault[i];
                }
            }
        }
    }

    //========================================
    for(uint8_t i=0; i < NUM_COILS; i++) {
        if(pwmPins[i]) {
            if (servoFiltered[i] == 0) {
                servoFiltered[i] = holdingRegs[i];
            }
            servoFiltered[i] = servoFiltered[i] * (1.0 - pwmSmooth[i]) + holdingRegs[i] * pwmSmooth[i];
            servos[i].writeMicroseconds(servoFiltered[i] + servosShift[i]);
        } else {
            digitalWrite(digitalPins[i], coils[i] ? HIGH : LOW);
        }
    }

    for(uint8_t i = 0; i < NUM_DISCRETE; i++) {
        discreteInputs[i] = digitalRead(digitalInPins[i]);
    }

    for(uint8_t i=0;i<NUM_INPUTS;i++) {
        inputRegs[i] = analogRead(analogPins[i]);
    }
}
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