ESP32 SIM808 GSM/GPRS + GPS Module

🛠️ SIM808 GSM/GPRS + GPS Module Troubleshooting

This guide outlines a systematic approach to troubleshoot and resolve common problems with the . Start by confirming that the hardware connections are correct, as wiring mistakes are the most frequent cause of issues. If you are sure the connections are correct, follow the below steps to debug common issues.

🔌 Module Fails to Power On

📶 SIM Card Not Recognized

📡 Poor Network Signal or Connectivity Issues

⌨️ AT Commands Not Responding

🛰️ GPS Functionality Not Working

💻 Code Examples

Below you can find code examples of SIM808 GSM/GPRS + GPS Module with ESP32 in several frameworks:

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

If you encounter issues while using the SIM808 GSM/GPRS + GPS Module, check the Common Issues Troubleshooting Guide.

ESP32 SIM808 Arduino IDE Code Example

Example in Arduino IDE

Fill in your main Arduino IDE sketch file with the following code to use the SIM808 GSM/GPRS + GPS Module:

#include <Arduino.h>

// Define ESP32 hardware serial port for SIM808
#define SIM808_TX 17  // ESP32 TX connected to SIM808 RX
#define SIM808_RX 16  // ESP32 RX connected to SIM808 TX
#define PWRKEY 9      // SIM808 Power Key pin (adjust if needed)

// Initialize hardware serial for SIM808
HardwareSerial sim808(2);

void powerOnSIM808() {
    pinMode(PWRKEY, OUTPUT);
    digitalWrite(PWRKEY, LOW);
    delay(1000);  // PWRKEY must be held LOW for at least 1 second
    digitalWrite(PWRKEY, HIGH);
    delay(5000);  // Wait for the module to initialize
}

void setup() {
    Serial.begin(115200);  // Serial Monitor
    sim808.begin(9600, SERIAL_8N1, SIM808_RX, SIM808_TX);  // SIM808 UART
    
    powerOnSIM808();

    Serial.println("Testing AT communication...");
    
    // Test AT command
    sendATCommand("AT");

    // Set SMS text mode
    sendATCommand("AT+CMGF=1");

    // Send SMS
    Serial.println("Sending SMS...");
    sim808.println("AT+CMGS=\"+1234567890\"");  // Replace with recipient's number
    delay(1000);
    sim808.print("Hello from ESP32 and SIM808");
    sim808.write(26); // CTRL+Z to send
    delay(5000);
    printResponse();
}

void loop() {
    // Add code to handle incoming messages or other functionalities
}

// Function to send an AT command and print response
void sendATCommand(const char *command) {
    Serial.print("Sending: ");
    Serial.println(command);
    sim808.println(command);
    delay(1000);
    printResponse();
}

// Function to print response from SIM808
void printResponse() {
    while (sim808.available()) {
        Serial.write(sim808.read());
    }
    Serial.println("
----------------------
");
}

This Arduino sketch interfaces with the SIM808 module using ESP32's hardware serial (UART2) for reliable communication.

Key Features #

• Hardware Serial (UART2) is used instead of SoftwareSerial.
• PWRKEY (GPIO9) powers on the SIM808 module.
• AT Commands test communication (AT), enable SMS mode (AT+CMGF=1), and send an SMS (AT+CMGS).
• GPS functionality can be added if needed.

Connections #

• ESP32 TX (GPIO17) → SIM808 RX
• ESP32 RX (GPIO16) → SIM808 TX
• Baud rate: 9600

Why Hardware Serial? #

• More stable and faster than SoftwareSerial.
• Dedicated UART2 prevents conflicts with Serial Monitor.

This setup allows SMS sending and further expansion for GPS or network functionalities. 🚀

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 SIM808 ESP-IDF Code Example

Example in Espressif IoT Framework (ESP-IDF)

If you're using ESP-IDF to work with the SIM808 GSM/GPRS + GPS 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 <string.h>
#include "driver/uart.h"
#include "driver/gpio.h"
#include "freertos/task.h"

#define TX_PIN 17
#define RX_PIN 16
#define PWRKEY_PIN 4
#define UART_PORT UART_NUM_1
#define GPS_UART_PORT UART_NUM_2

void init_uart() {
    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);
}

void power_on_sim808() {
    gpio_set_direction(PWRKEY_PIN, GPIO_MODE_OUTPUT);
    gpio_set_level(PWRKEY_PIN, 0);
    vTaskDelay(1000 / portTICK_PERIOD_MS); // Hold PWRKEY low for 1 second
    gpio_set_level(PWRKEY_PIN, 1);
    vTaskDelay(5000 / portTICK_PERIOD_MS); // Wait for the module to initialize
}

void app_main(void) {
    init_uart();
    power_on_sim808();

    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 initializes UART communication with the SIM808 module and powers it on using the PWRKEY pin (GPIO4). 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. Additional UART configurations can be added for GPS functionality.

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 SIM808 ESPHome Code Example

Example in ESPHome (Home Assistant)

Fill in this configuration in your ESPHome YAML configuration file (example.yml) to integrate the SIM808 GSM/GPRS + GPS Module

uart:
  tx_pin: GPIO17
  rx_pin: GPIO16
  baud_rate: 9600

switch:
  - platform: gpio
    name: "SIM808 Power"
    pin:
      number: GPIO4
      inverted: true

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

sensor:
  - platform: custom
    lambda: |-
      return {nullptr};
    sensors:
      - name: "SIM808 Response"

The ESPHome configuration sets up UART communication with the SIM808 using GPIO17 (TX) and GPIO16 (RX) at 9600 baud. A GPIO-based switch is used to control the PWRKEY pin (GPIO4) for powering the module on or off. A template switch allows sending the AT command, and a custom sensor can be implemented to process responses from the module. GPS functionality can also be integrated through additional configuration.

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

ESP32 SIM808 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:sim808]
platform = espressif32
board = esp32dev
framework = arduino
monitor_speed = 115200

ESP32 SIM808 PlatformIO Example Code

Write this code in your PlatformIO project under the src/main.cpp file to use the SIM808 GSM/GPRS + GPS Module:

#include <HardwareSerial.h>
#include <Arduino.h>

HardwareSerial sim808(1);
#define PWRKEY 4

void power_on_sim808() {
    pinMode(PWRKEY, OUTPUT);
    digitalWrite(PWRKEY, LOW);
    delay(1000); // Hold PWRKEY low for 1 second
    digitalWrite(PWRKEY, HIGH);
    delay(5000); // Wait for initialization
}

void setup() {
    Serial.begin(115200);
    sim808.begin(9600, SERIAL_8N1, 16, 17); // RX, TX
    power_on_sim808();

    // Test AT command
    sim808.println("AT");
    delay(1000);
    while (sim808.available()) {
        Serial.write(sim808.read());
    }
}

void loop() {
    sim808.println("AT+CMGF=1"); // Set SMS to text mode
    delay(1000);
    sim808.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
    delay(1000);
    sim808.print("Hello from PlatformIO");
    delay(1000);
    sim808.write(26); // CTRL+Z to send SMS
    delay(5000);
}

This PlatformIO code interfaces with the SIM808 module using HardwareSerial on an ESP32. The `power_on_sim808` function toggles the PWRKEY pin (GPIO4) to activate the module. 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 SIM808 MicroPython Code Example

Example in Micro Python Framework

Fill in this script in your MicroPython main.py file (main.py) to integrate the SIM808 GSM/GPRS + GPS Module with your ESP32.

from machine import UART, Pin
import time

# Initialize UART
uart = UART(2, baudrate=9600, tx=17, rx=16)
pwrkey = Pin(4, Pin.OUT)

def power_on_sim808():
    pwrkey.value(0)
    time.sleep(1)  # Hold PWRKEY low for 1 second
    pwrkey.value(1)
    time.sleep(5)  # Wait for module to initialize

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

# Power on the module
power_on_sim808()

# 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 SIM808 module over UART. The `power_on_sim808` function activates the module using the PWRKEY pin (GPIO4). The `send_at` function sends AT commands and prints the responses. The script initializes the module, tests communication, and sends an SMS with a specified message. Additional logic can be added to read GPS data through UART.

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