Serial Communication Between Arduino and ESP32 CAM

Serial communication transmits data one bit at a time, sequentially, over a communication channel or computer bus. In the context of Arduino and ESP32, serial communication refers to the transmission of data serially over a single wire or communication line rather than in parallel over multiple wires.

Serial communication between Arduino and ESP32 CAM
Serial communication between Arduino and ESP32 CAM

Two main types of serial communication are commonly used with Arduino and ESP32:

  • Asynchronous serial communication: Data is transmitted without a clock signal in asynchronous serial communication. Instead, each data frame's start and stop bits are used to synchronize the communication. Asynchronous serial communication is commonly used for communication over long distances, such as with modems.
  • Synchronous serial communication: A clock signal synchronizes data transmission in synchronous serial communication. Synchronous serial communication is typically faster than asynchronous serial communication and is often used for communication between devices on a single circuit board or over short distances.

Both Arduino and ESP32 support both asynchronous and synchronous serial communication. The Arduino Uno has a single hardware serial port (UART) that can be used for serial communication, while the ESP32 has multiple hardware UARTs that can be used for serial communication. Arduino and ESP32 support software-based serial communication using libraries such as SoftwareSerial (for Arduino) and HardwareSerial (for ESP32).

Circuit diagram of Serial communication between Arduino and ESP32:

The voltage levels of the Arduino Uno and ESP32 are not compatible with direct communication without some form of voltage level shifting. The Arduino Uno operates at 5 volts, while the ESP32 operates at 3.3 volts. If you connect the RX and TX pins of the Arduino Uno and ESP32 directly, you could damage the ESP32 due to the higher voltage.

One way to safely establish serial communication between the Arduino Uno and ESP32 is to use a voltage divider circuit to step down the voltage from the Arduino Uno to a level compatible with the ESP32. A voltage divider is a simple circuit that consists of two resistors connected in series. The voltage at the center point between the two resistors is given by:

Vout = Vin * R2 / (R1 + R2)

To use a voltage divider to step down the voltage from the Arduino Uno to the ESP32, you would connect the Arduino Uno's RX pin to one end of the voltage divider and the ESP32's RX pin to the other end. You would then connect the center point of the voltage divider to the ESP32's RX pin.

Here is an example circuit that demonstrates how you can use a voltage divider to establish serial communication between an Arduino Uno and an ESP32:

Voltage divider

In this circuit, R1 is a 10K ohm resistor, and R2 is a 4.7K ohm resistor. This results in a voltage of 3.3 volts at the center point between the two resistors. This voltage is compatible with the ESP32 and can be used to establish serial communication between the Arduino Uno and ESP32.

Remember that you will need to connect the TX pin of the Arduino Uno to the TX pin of the ESP32 similarly, using a voltage divider to step down the voltage from the ESP32 to a level compatible with the Arduino Uno.

After implementing the voltage divider in between Arduino TX and ESP32 RX, the circuit will look like the following:

Serial Communication Between Arduino and ESP32 CAM
Arduino ESP32 Serial Communication with Voltage Divider

Code for ESP32 CAM:

Here is an example of how you can establish serial communication between an Arduino Uno and an ESP32-CAM:

#include <Arduino.h>
void setup() {
  Serial.begin(115200); // Initialize the hardware serial port
}
void loop() {
  if (Serial.available()) {
    char data = Serial.read();
    // Process the received data here
    // Echo back the data to the serial port
    Serial.write(data);
  }
}code-box

In the ESP32-CAM code, we use the built-in Serial object to communicate with the Arduino Uno. On the Arduino Uno side, we create a SoftwareSerial object mySerial and initialize it with the RX and TX pins (in this case, pins 2 and 3). The mySerial object is used to communicate with the ESP32-CAM.

Code for Arduino

In Arduino, upload the following code:

#include <SoftwareSerial.h>
SoftwareSerial mySerial(2, 3); // RX, TX pins for SoftwareSerial
void setup() {
  Serial.begin(9600); // Initialize the hardware serial port for debugging
  mySerial.begin(115200); // Initialize the software serial port
}
void loop() {
  if (mySerial.available()) {
    char data = mySerial.read();
    // Process the received data here
    // Echo back the data to the serial port
    mySerial.write(data);
  }
}code-box

Make sure you have the SoftwareSerial library installed on your Arduino IDE. You can install it by going to "Sketch -> Include Library -> Manage Libraries" and searching for "SoftwareSerial."

It's important to note that the baud rate, the speed at which the data is transmitted, must be the same on both the Arduino and the ESP32 CAM for the communication to work correctly.

The video documentation on Arduino and ESP32 Serial Communication

Here is a YouTube video that demonstrates how to establish serial communication between the Arduino and the ESP32 using the Arduino IDE:

Recap

This article is a comprehensive guide for establishing serial communication between an Arduino and an ESP32-CAM module. It offers detailed example code, emphasizes the utilization of the SoftwareSerial library for the Arduino, and underscores the significance of matching baud rates to ensure seamless data exchange. By following the step-by-step instructions outlined in the article, you can establish reliable and effective serial communication, thus unlocking the full potential of Arduino-ESP32-CAM projects.

11/Post a Comment/Comments

  1. What kind of data can I send over serial communication between the ESP32 CAM and an Arduino?

    ReplyDelete
    Replies
    1. You can send various data over serial communication between the ESP32 CAM and an Arduino, including image data, sensor data, and control signals.

      For example, you can use the ESP32 CAM to capture an image and then send the image data to Arduino for processing. You can also use the Arduino to control the ESP32 CAM, for example, by sending commands to the ESP32 CAM to adjust camera settings or capture images.

      Delete
  2. Can I use the ESP32 CAM and an Arduino to create a remote monitoring system?

    ReplyDelete
    Replies
    1. You can create a remote monitoring system using the ESP32 CAM and an Arduino. Here's an example scenario:

      Let's say you want to monitor your backyard for security purposes. You can set up the system as follows:

      Hardware setup: Connect the ESP32 CAM and an Arduino using a TTL-to-USB converter. Power, the ESP32 CAM, and the Arduino using separate power supplies.

      Software setup: Use the Arduino IDE to program the Arduino and the ESP32 CAM. Install the required libraries for the ESP32 CAM, such as the ESP32-CAM library and the OV2640 camera library.

      Configure the ESP32 CAM to capture images or video regularly and save the data to the onboard SD card.

      Use the Arduino to process the data from the ESP32 CAM and send it to a remote location over the internet. You can use a wireless module, such as an ESP8266, to connect the Arduino to the internet. Alternatively, a cellular module, such as a SIM800L, can send data over a cellular network.

      Use a web application or mobile app to access the data from the remote location and monitor the system. You can use a cloud service, such as AWS or Firebase, to store and access the data.

      In this scenario, the ESP32 CAM can be set up to capture images every minute and save the photos to the SD card. The Arduino can be programmed to read the images from the SD card and send them to a cloud storage service, such as AWS S3, using the wireless or cellular module. You can then use a web application or mobile app to access the images and monitor your backyard remotely. You can also set up alerts on your phone or email if motion is detected in the photos.

      A remote monitoring system using the ESP32 CAM and an Arduino can be a cost-effective and flexible solution for home security and other monitoring applications.
      Feel free to ask any questions regarding ESP32 CAM; I will try to answer or write an article with explanations and resources like circuits, code, etc.

      Delete
  3. Can u please show the code for the esp32 cam and arduino uno? I tried running code on esp32 cam and it says an error about the SoftwareSerial library, if I run the code on arduino uno it's good. I would like to see both codes so I could make a better idea how to use it. Thank you!

    ReplyDelete
    Replies
    1. The ESP32-CAM module has a built-in hardware serial interface, so you don't need to use the SoftwareSerial library. However, the Arduino Uno doesn't have multiple hardware serial ports, so you must use SoftwareSerial on the Arduino Uno. The code provided can serve your need. Thanks.

      Delete
  4. how do i do this with esp32 and esp32 cam?

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    Replies
    1. Serial communication between an ESP32 and an ESP32-CAM (Camera Module) involves establishing a connection using the UART (Universal Asynchronous Receiver-Transmitter) interface. Here's a brief overview:

      Hardware Connections:
      ESP32 to ESP32-CAM:
      Connect the TX pin of the ESP32 to the RX pin of the ESP32-CAM.
      Connect the RX pin of the ESP32 to the TX pin of the ESP32-CAM.
      Ensure that both devices share a common ground (GND).
      Code for ESP32 (Arduino IDE):

      void setup() {
      Serial.begin(115200); // Begin serial communication with a baud rate of 115200
      }

      void loop() {
      if (Serial.available() > 0) {
      char incomingChar = Serial.read();
      // Process the received character as needed
      }
      // Your main code here
      }
      Code for ESP32-CAM (Arduino IDE):

      #include

      HardwareSerial Serial2(2); // Use Serial2 for ESP32-CAM

      void setup() {
      Serial2.begin(115200); // Begin serial communication with a baud rate of 115200
      }

      void loop() {
      if (Serial2.available() > 0) {
      char incomingChar = Serial2.read();
      // Process the received character as needed
      }
      // Your main code here
      }

      Important Points:
      Baud Rate: Ensure that the baud rate is consistent between both ESP32 modules. In the examples, a baud rate of 115200 is used, but you can choose a different rate if needed.

      HardwareSerial: The ESP32-CAM uses Serial2 instead of the default Serial for communication. Make sure to include the HardwareSerial library.

      Power Supply: ESP32-CAM may require an external power supply due to the power demands of the camera module.

      GPIO Pins: Make sure you are using appropriate GPIO pins for TX and RX connections, and consider the power requirements of the ESP32-CAM, as it might need an external power supply.

      Delete
  5. Can I send data from from esp32 that has a library that can detect whether it is a robot or battery to Arduino uno?

    ReplyDelete
    Replies
    1. Can you please explain your quary? I don't understand what you want to know.

      Delete
  6. Hello, i have esp32-cam with esp32-cam-mb can i use your diagram with the mb plugged in and used as a power source?

    ReplyDelete

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