const int sensorPin = A0; // MQ-3 sensor connected to analog pin A0
const int ledPin = 13; // LED connected to digital pin 13
const float refVoltage = 5.0; // Reference voltage for the sensor
const float voutToAlcoholRatio = 0.0048828125; // Ratio to convert voltage output to alcohol concentration

void setup() {
  Serial.begin(9600); // Initialize serial communication at 9600 bps
  pinMode(ledPin, OUTPUT); // Set LED pin as output
}

void loop() {
  float sensorVoltage = analogRead(sensorPin) * refVoltage / 1023.0; // Read analog input and convert to voltage
  float alcoholConcentration = sensorVoltage / voutToAlcoholRatio; // Convert voltage to alcohol concentration
  Serial.print("Alcohol Concentration: "); // Print the alcohol concentration to the serial monitor
  Serial.print(alcoholConcentration);
  Serial.println(" ppm");
  if (alcoholConcentration >= 0.5) { // If the alcohol concentration is above the threshold, turn on the LED
    digitalWrite(ledPin, HIGH);
  } else {
    digitalWrite(ledPin, LOW); // Otherwise, turn off the LED
  }
  delay(1000); // Wait for 1 second before taking the next reading
}

This code reads the analog output of the MQ-3 alcohol sensor connected to analog pin A0 and converts the voltage output to alcohol concentration in parts per million (ppm) using the voutToAlcoholRatio. The alcohol concentration is then printed to the serial monitor and compared to a threshold of 0.5 ppm. If the concentration is above the threshold, the LED connected to digital pin 13 is turned on. The code then waits for 1 second before taking the next reading. Note that the threshold value may need to be adjusted depending on the sensitivity of the sensor and the desired level of accuracy.

#include "esp_camera.h"

// Define camera pins
#define PWDN_GPIO_NUM     32
#define RESET_GPIO_NUM    -1
#define XCLK_GPIO_NUM      0
#define SIOD_GPIO_NUM     26
#define SIOC_GPIO_NUM     27

#define Y9_GPIO_NUM       35
#define Y8_GPIO_NUM       34
#define Y7_GPIO_NUM       39
#define Y6_GPIO_NUM       36
#define Y5_GPIO_NUM       21
#define Y4_GPIO_NUM       19
#define Y3_GPIO_NUM       18
#define Y2_GPIO_NUM        5
#define VSYNC_GPIO_NUM    25
#define HREF_GPIO_NUM     23
#define PCLK_GPIO_NUM     22

void setup() {
  Serial.begin(115200);
  // Initialize camera
  camera_config_t config;
  config.ledc_channel = LEDC_CHANNEL_0;
  config.ledc_timer = LEDC_TIMER_0;
  config.pin_d0 = Y2_GPIO_NUM;
  config.pin_d1 = Y3_GPIO_NUM;
  config.pin_d2 = Y4_GPIO_NUM;
  config.pin_d3 = Y5_GPIO_NUM;
  config.pin_d4 = Y6_GPIO_NUM;
  config.pin_d5 = Y7_GPIO_NUM;
  config.pin_d6 = Y8_GPIO_NUM;
  config.pin_d7 = Y9_GPIO_NUM;
  config.pin_xclk = XCLK_GPIO_NUM;
  config.pin_pclk = PCLK_GPIO_NUM;
  config.pin_vsync = VSYNC_GPIO_NUM;
  config.pin_href = HREF_GPIO_NUM;
  config.pin_sscb_sda = SIOD_GPIO_NUM;
  config.pin_sscb_scl = SIOC_GPIO_NUM;
  config.pin_pwdn = PWDN_GPIO_NUM;
  config.pin_reset = RESET_GPIO_NUM;
  config.xclk_freq_hz = 20000000;
  config.pixel_format = PIXFORMAT_JPEG;
  // Set the resolution
  config.frame_size = FRAMESIZE_SVGA;
  config.jpeg_quality = 12;
  config.fb_count = 1;
  // Initialize the camera
  esp_err_t err = esp_camera_init(&config);
  if (err != ESP_OK) {
    Serial.printf("Camera init failed with error 0x%x", err);
    return;
  }
  Serial.println("Camera initialized successfully");
}

void loop() {
  // Start video streaming
  Serial.println("Starting video streaming");
  camera_fb_t *fb = NULL;
  esp_err_t res = ESP_OK;
  while (true) {
    fb = esp_camera_fb_get();
    if (!fb) {
      Serial.println("Failed to capture frame");
      res = ESP_FAIL;
      break;
    }
    // Send the frame to serial port
    Serial.write(fb->buf, fb->len);
    // Release the memory
    esp_camera_fb_return(fb);
  }
  // Stop video streaming
  Serial.println("Stopping video streaming");
}

This code initializes the ESP32-CAM camera and starts video streaming using the esp_camera_fb_get() function. The frames are then sent to the serial port using the Serial.write() function. You can adjust the camera settings such as resolution and quality in the camera_config_t struct. Note that video streaming can be resource-intensive and may require additional optimization for better performance.

#include "esp_camera.h"

// Define camera pins
#define PWDN_GPIO_NUM     32
#define RESET_GPIO_NUM    -1
#define XCLK_GPIO_NUM      0
#define SIOD_GPIO_NUM     26
#define SIOC_GPIO_NUM     27

#define Y9_GPIO_NUM       35
#define Y8_GPIO_NUM       34
#define Y7_GPIO_NUM       39
#define Y6_GPIO_NUM       36
#define Y5_GPIO_NUM       21
#define Y4_GPIO_NUM       19
#define Y3_GPIO_NUM       18
#define Y2_GPIO_NUM        5
#define VSYNC_GPIO_NUM    25
#define HREF_GPIO_NUM     23
#define PCLK_GPIO_NUM     22

void setup() {
  Serial.begin(115200);
  // Initialize camera
  camera_config_t config;
  config.ledc_channel = LEDC_CHANNEL_0;
  config.ledc_timer = LEDC_TIMER_0;
  config.pin_d0 = Y2_GPIO_NUM;
  config.pin_d1 = Y3_GPIO_NUM;
  config.pin_d2 = Y4_GPIO_NUM;
  config.pin_d3 = Y5_GPIO_NUM;
  config.pin_d4 = Y6_GPIO_NUM;
  config.pin_d5 = Y7_GPIO_NUM;
  config.pin_d6 = Y8_GPIO_NUM;
  config.pin_d7 = Y9_GPIO_NUM;
  config.pin_xclk = XCLK_GPIO_NUM;
  config.pin_pclk = PCLK_GPIO_NUM;
  config.pin_vsync = VSYNC_GPIO_NUM;
  config.pin_href = HREF_GPIO_NUM;
  config.pin_sscb_sda = SIOD_GPIO_NUM;
  config.pin_sscb_scl = SIOC_GPIO_NUM;
  config.pin_pwdn = PWDN_GPIO_NUM;
  config.pin_reset = RESET_GPIO_NUM;
  config.xclk_freq_hz = 20000000;
  config.pixel_format = PIXFORMAT_JPEG;
  // Set the resolution
  config.frame_size = FRAMESIZE_SVGA;
  config.jpeg_quality = 12;
  config.fb_count = 1;
  // Initialize the camera
  esp_err_t err = esp_camera_init(&config);
  if (err != ESP_OK) {
    Serial.printf("Camera init failed with error 0x%x", err);
    return;
  }
  Serial.println("Camera initialized successfully");
}

void loop() {
  // Capture a photo
  camera_fb_t *fb = esp_camera_fb_get();
  if (!fb) {
    Serial.println("Failed to capture photo");
    return;
  }
  // Send the photo to serial port
  Serial.write(fb->buf, fb->len);
  // Release the memory
  esp_camera_fb_return(fb);
  delay(1000); // Wait for a second
}

This code initializes the ESP32-CAM camera and captures a photo using the esp_camera_fb_get() function. The photo is then sent to the serial port using the Serial.write() function. You can adjust the camera settings such as resolution and quality in the camera_config_t struct.

Here are some commonly used JavaScript string methods:

1. length: Returns the length of a string.

   const str = 'Hello, World!';
   console.log(str.length); // Output: 13​

2. toUpperCase(): Converts a string to uppercase.

   const str = 'Hello, World!';
   console.log(str.toUpperCase()); // Output: HELLO, WORLD!​

3. toLowerCase(): Converts a string to lowercase.

   const str = 'Hello, World!';
   console.log(str.toLowerCase()); // Output: hello, world!​

4. indexOf(): Returns the index of the first occurrence of a specified value in a string.

   const str = 'Hello, World!';
   console.log(str.indexOf('World')); // Output: 7​

5. slice(): Extracts a part of a string and returns a new string.

   const str = 'Hello, World!';
   console.log(str.slice(7)); // Output: World!
   console.log(str.slice(7, 12)); // Output: World​

6. replace(): Searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced.

   const str = 'Hello, World!';
   console.log(str.replace('World', 'Universe')); // Output: Hello, Universe!​

7. split(): Splits a string into an array of substrings.

   const str = 'Hello, World!';
   console.log(str.split(',')); // Output: ['Hello', ' World!']​

8. trim(): Removes whitespace from both ends of a string.

   const str = '   Hello, World!   ';
   console.log(str.trim()); // Output: Hello, World!​

These are just a few of the many available JavaScript string methods.