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cyrusmeh/ESP32-CAM License Plate Recognition | AI-Powered LPR System Tutorial.ino

Created April 1, 2025 18:57
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In this comprehensive tutorial, we’ll guide you through building a License Plate Recognition System using the ESP32-CAM. You’ll receive step-by-step instructions, complete with a circuit diagram and code, to help you capture images of cars and bikes. We’ll show you how to send these images to a cloud server powered by AI for license plate recogn…
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ESP32-CAM License Plate Recognition | AI-Powered LPR System Tutorial.ino
// Libraries for WiFi, Secure Client, and Camera functionalities
#include <Arduino.h>
#include <WiFi.h>
#include <WiFiClientSecure.h>
#include "soc/soc.h"
#include "soc/rtc_cntl_reg.h"
#include "esp_camera.h"
/* I2C and OLED Display Includes ------------------------------------------- */
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
// ESP32-CAM doesn't have dedicated I2C pins, so we define our own
#define I2C_SDA 15
#define I2C_SCL 14
TwoWire I2Cbus = TwoWire(0);
// Display defines
#define SCREEN_WIDTH 128
#define SCREEN_HEIGHT 64
#define OLED_RESET -1
#define SCREEN_ADDRESS 0x3C
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &I2Cbus, OLED_RESET);
const char* ssid = "xxx"; // Replace "xxx" with your WiFi SSID
const char* password = "xxx"; // Replace "xxx" with your WiFi Password
String serverName = "www.circuitdigest.cloud"; // Replace with your server domain
String serverPath = "/readnumberplate"; // API endpoint path "/readqrcode" "/readnumberplate"
const int serverPort = 443; // HTTPS port
String apiKey = "xxx"; // Replace "xxx" with your API key
#define triggerButton 13 // GPIO pin for the trigger button
#define flashLight 4 // GPIO pin for the flashlight
int count = 0; // Counter for image uploads
WiFiClientSecure client; // Secure client for HTTPS communication
// Camera GPIO pins - adjust based on your ESP32-CAM board
#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
// Function to extract a JSON string value by key
String extractJsonStringValue(const String& jsonString, const String& key) {
int keyIndex = jsonString.indexOf(key);
if (keyIndex == -1) {
return "";
}
int startIndex = jsonString.indexOf(':', keyIndex) + 2;
int endIndex = jsonString.indexOf('"', startIndex);
if (startIndex == -1 || endIndex == -1) {
return "";
}
return jsonString.substring(startIndex, endIndex);
}
// Function to display text on OLED
void displayText(String text) {
display.clearDisplay();
display.setCursor(0, 10);
display.setTextSize(1);
display.setTextColor(SSD1306_WHITE);
display.print(text);
display.display();
}
void setup() {
// Disable brownout detector
WRITE_PERI_REG(RTC_CNTL_BROWN_OUT_REG, 0);
Serial.begin(115200);
pinMode(flashLight, OUTPUT);
pinMode(triggerButton, INPUT);
digitalWrite(flashLight, LOW);
// Connect to WiFi
WiFi.mode(WIFI_STA);
Serial.println();
Serial.print("Connecting to ");
Serial.println(ssid);
WiFi.begin(ssid, password);
while (WiFi.status() != WL_CONNECTED) {
Serial.print(".");
delay(500);
}
Serial.println();
Serial.print("ESP32-CAM IP Address: ");
Serial.println(WiFi.localIP());
// Configure 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;
// Adjust frame size and quality based on PSRAM availability
if (psramFound()) {
config.frame_size = FRAMESIZE_SVGA;
config.jpeg_quality = 5; // Lower number means higher quality (0-63)
config.fb_count = 2;
Serial.println("PSRAM found");
} else {
config.frame_size = FRAMESIZE_CIF;
config.jpeg_quality = 12; // Lower number means higher quality (0-63)
config.fb_count = 1;
}
// Initialize camera
esp_err_t err = esp_camera_init(&config);
if (err != ESP_OK) {
Serial.printf("Camera init failed with error 0x%x", err);
delay(1000);
ESP.restart();
}
// Initialize I2C with our defined pins
I2Cbus.begin(I2C_SDA, I2C_SCL, 100000);
// Initialize OLED display
//if (!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
Serial.printf("SSD1306 OLED display failed to initialize.\nCheck that display SDA is connected to pin %d and SCL connected to pin %d\n", I2C_SDA, I2C_SCL);
while (true);
}
// Display initialization messages
displayText("System Initialization Successful");
delay(1000);
displayText("Press Trigger Button \n\nto Start Capturing");
}
void loop() {
// Check if trigger button is pressed
if (digitalRead(triggerButton) == HIGH) {
int status = sendPhoto();
if (status == -1) {
displayText("Image Capture Failed");
} else if (status == -2) {
displayText("Server Connection Failed");
}
}
}
// Function to capture and send photo to the server
int sendPhoto() {
camera_fb_t* fb = NULL;
// Turn on flash light and capture image
// digitalWrite(flashLight, HIGH);
delay(100);
fb = esp_camera_fb_get();
delay(100);
if (!fb) {
Serial.println("Camera capture failed");
return -1;
}
// Display success message
displayText("Image Capture Success");
delay(300);
// digitalWrite(flashLight, LOW);
// Connect to server
Serial.println("Connecting to server:" + serverName);
displayText("Connecting to server:\n\n" + serverName);
client.setInsecure(); // Skip certificate validation for simplicity
if (client.connect(serverName.c_str(), serverPort)) {
Serial.println("Connection successful!");
displayText("Connection successful!");
delay(300);
displayText("Data Uploading !");
// Increment count and prepare file name
count++;
Serial.println(count);
String filename = apiKey + ".jpeg";
// Prepare HTTP POST request
String head = "--CircuitDigest\r\nContent-Disposition: form-data; name=\"imageFile\"; filename=\"" + filename + "\"\r\nContent-Type: image/jpeg\r\n\r\n";
String tail = "\r\n--CircuitDigest--\r\n";
uint32_t imageLen = fb->len;
uint32_t extraLen = head.length() + tail.length();
uint32_t totalLen = imageLen + extraLen;
client.println("POST " + serverPath + " HTTP/1.1");
client.println("Host: " + serverName);
client.println("Content-Length: " + String(totalLen));
client.println("Content-Type: multipart/form-data; boundary=CircuitDigest");
client.println("Authorization:" + apiKey);
client.println();
client.print(head);
// Send image data in chunks
uint8_t* fbBuf = fb->buf;
size_t fbLen = fb->len;
for (size_t n = 0; n < fbLen; n += 1024) {
if (n + 1024 < fbLen) {
client.write(fbBuf, 1024);
fbBuf += 1024;
} else {
size_t remainder = fbLen % 1024;
client.write(fbBuf, remainder);
}
}
client.print(tail);
// Clean up
esp_camera_fb_return(fb);
displayText("Waiting For Response!");
// Wait for server response
String response;
long startTime = millis();
while (client.connected() && millis() - startTime < 5000) { // Modifify the Waiting time as per the response time
if (client.available()) {
char c = client.read();
response += c;
}
}
// Extract and display NPR data from response
String NPRData = extractJsonStringValue(response, "\"number_plate\"");
String imageLink = extractJsonStringValue(response, "\"view_image\"");
// Serial.print("NPR DATA: ");
// Serial.println(NPRData);
// Serial.print("ImageLink: ");
// Serial.println(imageLink);
Serial.print("Response: ");
Serial.println(response);
displayText("NPR Data:\n\n" + NPRData);
client.stop();
esp_camera_fb_return(fb);
return 0;
} else {
Serial.println("Connection to server failed");
esp_camera_fb_return(fb);
return -2;
}
}
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