ESP32 SIM800L GSM/GPRS Module

Code Examples

Below you can find code examples of SIM800L GSM/GPRS Module with ESP32 in several frameworks:

• Arduino IDE
• ESP-IDF
• ESPHome
• PlatformIO
• MicroPython

If you encounter issues while using the SIM800L GSM/GPRS Module, check the Common Issues Troubleshooting Guide.

ESP32 SIM800L Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the SIM800L GSM/GPRS Module:

#include <SoftwareSerial.h>

SoftwareSerial sim800l(10, 11); // RX, TX

void setup() {
    Serial.begin(9600);
    sim800l.begin(9600);

    // Send AT command to test communication
    Serial.println("Sending: AT");
    sim800l.println("AT");
    delay(1000);
    while (sim800l.available()) {
        Serial.write(sim800l.read());
    }
}

void loop() {
    // Send an SMS
    sim800l.println("AT+CMGF=1"); // Set SMS to text mode
    delay(1000);
    sim800l.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
    delay(1000);
    sim800l.print("Hello from SIM800L");
    delay(1000);
    sim800l.write(26); // CTRL+Z to send SMS
    delay(5000);
}

This Arduino sketch interfaces with the SIM800L module using the SoftwareSerial library. The module is initialized, and a basic AT command is sent to verify communication. In the loop, the sketch sends an SMS to a specified number by setting the module to SMS text mode, providing the recipient's number, and sending the message. The message is finalized with CTRL+Z (ASCII 26) to trigger the transmission.

Connect your ESP32 to your computer via a USB cable, Ensure the correct Board and Port are selected under Tools, Click the "Upload" button in the Arduino IDE to compile and upload the code to your ESP32.

ESP32 SIM800L ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the SIM800L GSM/GPRS Module, here's how you can set it up and read data from the sensor. Fill in this code in the main ESP-IDF file:

#include <stdio.h>
#include "driver/uart.h"
#include "freertos/task.h"

#define TX_PIN 17
#define RX_PIN 16
#define UART_PORT UART_NUM_1

void app_main(void) {
    uart_config_t uart_config = {
        .baud_rate = 9600,
        .data_bits = UART_DATA_8_BITS,
        .parity = UART_PARITY_DISABLE,
        .stop_bits = UART_STOP_BITS_1,
        .flow_ctrl = UART_HW_FLOWCTRL_DISABLE
    };

    uart_param_config(UART_PORT, &uart_config);
    uart_set_pin(UART_PORT, TX_PIN, RX_PIN, UART_PIN_NO_CHANGE, UART_PIN_NO_CHANGE);
    uart_driver_install(UART_PORT, 1024, 0, 0, NULL, 0);

    char *test_cmd = "AT\r\n";
    uart_write_bytes(UART_PORT, test_cmd, strlen(test_cmd));

    while (true) {
        char data[128];
        int len = uart_read_bytes(UART_PORT, data, sizeof(data), 100 / portTICK_PERIOD_MS);
        if (len > 0) {
            data[len] = '\0';
            printf("Response: %s\n", data);
        }
        vTaskDelay(1000 / portTICK_PERIOD_MS);
    }
}

This ESP-IDF example demonstrates UART communication with the SIM800L module. The UART interface is configured with GPIO17 as TX and GPIO16 as RX. An AT command is sent to test communication, and responses from the module are printed to the console. The module’s replies are read using the uart_read_bytes function in a loop.

Update the I2C pins (I2C_MASTER_SDA_IO and I2C_MASTER_SCL_IO) to match your ESP32 hardware setup, Use idf.py build to compile the project, Use idf.py flash to upload the code to your ESP32.

ESP32 SIM800L ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the SIM800L GSM/GPRS Module

uart:
  tx_pin: GPIO17
  rx_pin: GPIO16
  baud_rate: 9600

switch:
  - platform: template
    name: "Send AT Command"
    turn_on_action:
      - uart.write: "AT\r\n"

sensor:
  - platform: custom
    lambda: |-
      return {nullptr};
    sensors:
      - name: "SIM800L Response"

The ESPHome configuration sets up UART communication with the SIM800L using GPIO17 (TX) and GPIO16 (RX) at 9600 baud. A template switch is used to send the AT command, and a custom sensor can be implemented to process responses from the module.

Upload this code to your ESP32 using the ESPHome dashboard or the esphome run command.

ESP32 SIM800L PlatformIO Code Example

Example in PlatformIO Framework

For PlatformIO, make sure to configure the platformio.ini file with the appropriate environment and libraries, and then proceed with the code.

Configure platformio.ini

First, your platformio.ini should look like below. You might need to include some libraries as shown. Make sure to change the board to your ESP32:

[env:sim800l]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

ESP32 SIM800L PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the SIM800L GSM/GPRS Module:

#include <HardwareSerial.h>

HardwareSerial sim800l(1);

void setup() {
    Serial.begin(115200);
    sim800l.begin(9600, SERIAL_8N1, 16, 17); // RX, TX

    sim800l.println("AT"); // Test AT command
    delay(1000);
    while (sim800l.available()) {
        Serial.write(sim800l.read());
    }
}

void loop() {
    sim800l.println("AT+CMGF=1"); // Set SMS to text mode
    delay(1000);
    sim800l.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
    delay(1000);
    sim800l.print("Hello from PlatformIO");
    delay(1000);
    sim800l.write(26); // CTRL+Z to send SMS
    delay(5000);
}

This PlatformIO code interfaces with the SIM800L module using HardwareSerial on an ESP32. The AT command is sent to test communication, and SMS functionality is implemented in the loop. GPIO16 (RX) and GPIO17 (TX) are configured as serial pins.

Upload the code to your ESP32 using the PlatformIO "Upload" button in your IDE or the pio run --target upload command.

ESP32 SIM800L MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the SIM800L GSM/GPRS Module with your ESP32.

from machine import UART
import time

# Initialize UART
uart = UART(2, baudrate=9600, tx=17, rx=16)

def send_at(command):
    uart.write(command + '\r\n')
    time.sleep(1)
    while uart.any():
        print(uart.read().decode('utf-8'), end='')

# Test communication
send_at('AT')

# Send SMS
send_at('AT+CMGF=1')  # Set SMS to text mode
send_at('AT+CMGS="+1234567890"')  # Replace with recipient's number
uart.write("Hello from MicroPython" + chr(26))

This MicroPython code communicates with the SIM800L module over UART. It defines a function to send AT commands and display the response. The script tests communication with an AT command and sends an SMS by setting the module to SMS text mode, specifying the recipient, and finalizing the message with CTRL+Z (ASCII 26).

Upload this code to your ESP32 using a MicroPython-compatible IDE, such as Thonny, uPyCraft, or tools like ampy.