How to Use SIM800L V2 EVB GSM MODULE: Examples, Pinouts, and Specs

The SIM800L V2 EVB GSM Module (Manufacturer: ROHS, Part ID: MOD31) is a compact and versatile GSM/GPRS module designed for communication over cellular networks. It supports SMS, voice calls, and data transmission, making it an ideal choice for Internet of Things (IoT) applications. The module operates on a wide voltage range and features an onboard antenna connector for enhanced signal reception.

• IoT devices requiring cellular connectivity
• Remote monitoring and control systems
• GPS tracking and fleet management
• Home automation and smart appliances
• SMS-based alert systems
• Voice communication in embedded systems

The SIM800L V2 EVB module has 8 pins. Below is the pinout and description:

1. Power Supply:

   • Use a stable power source capable of providing 3.7V to 4.2V with at least 2A peak current.
   • A LiPo battery or a DC-DC buck converter is recommended for reliable operation.
   • Connect the power source to the VCC and GND pins.

2. Microcontroller Connection:

   • Connect the TXD pin of the SIM800L to the RX pin of the microcontroller.
   • Connect the RXD pin of the SIM800L to the TX pin of the microcontroller.
   • Use a logic level shifter if your microcontroller operates at 5V logic levels, as the SIM800L uses 3.3V logic.

3. Antenna:

   • Attach an IPX/U.FL antenna to the onboard connector for better signal reception.

4. SIM Card:

   • Insert a micro SIM card into the SIM card slot. Ensure the card is activated and has sufficient balance for SMS, calls, or data.

5. Reset and Sleep Mode:

   • Use the RST pin to reset the module if needed.
   • The DTR pin can be used to enable sleep mode for power saving.

6. Network Status:

   • Monitor the NET pin to check the GSM network status. The blinking pattern indicates the connection state.

Below is an example of how to send an SMS using the SIM800L module with an Arduino UNO:

#include <SoftwareSerial.h>

// Define RX and TX pins for SoftwareSerial
SoftwareSerial SIM800L(10, 11); // RX = Pin 10, TX = Pin 11

void setup() {
  // Initialize serial communication
  Serial.begin(9600); // For debugging
  SIM800L.begin(9600); // For SIM800L communication

  // Wait for the module to initialize
  delay(1000);
  Serial.println("Initializing SIM800L...");

  // Send AT command to check communication
  SIM800L.println("AT");
  delay(1000);
  while (SIM800L.available()) {
    Serial.write(SIM800L.read());
  }

  // Set SMS text mode
  SIM800L.println("AT+CMGF=1"); // Set SMS to text mode
  delay(1000);

  // Send SMS
  SIM800L.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's phone number
  delay(1000);
  SIM800L.println("Hello from SIM800L!"); // SMS content
  delay(1000);
  SIM800L.write(26); // Send Ctrl+Z to send the SMS
  delay(5000);

  Serial.println("SMS sent!");
}

void loop() {
  // No actions in the loop
}

• Ensure the power supply can handle the module's peak current of 2A to avoid unexpected resets.
• Use a decoupling capacitor (e.g., 1000µF) near the VCC pin to stabilize the power supply.
• Place the antenna away from other components to minimize interference.
• Avoid using the module in areas with poor GSM signal strength to prevent excessive power consumption.

1. Module Keeps Restarting:

   • Cause: Insufficient power supply.
   • Solution: Use a power source capable of providing at least 2A peak current. Add a decoupling capacitor near the VCC pin.

2. No Network Connection:

   • Cause: Poor signal strength or incorrect SIM card.
   • Solution: Check the antenna connection and ensure the SIM card is activated and inserted correctly.

3. No Response to AT Commands:

   • Cause: Incorrect UART connection or baud rate.
   • Solution: Verify the RXD and TXD connections. Ensure the baud rate matches the module's default (9600 bps).

4. SMS Not Sending:

   • Cause: Incorrect SMS center number or insufficient balance.
   • Solution: Verify the SMS center number with the AT+CSCA command. Check the SIM card balance.

• Q: Can the SIM800L module work with 5V logic microcontrollers?
  A: No, the SIM800L uses 3.3V logic. Use a logic level shifter for compatibility with 5V microcontrollers.

• Q: What type of antenna should I use?
  A: Use an IPX/U.FL-compatible GSM antenna for optimal performance.

• Q: How do I check the signal strength?
  A: Use the AT+CSQ command. The response indicates the signal quality (0-31, where 31 is the best).

• Q: Can I use the module for internet access?
  A: Yes, the SIM800L supports GPRS for data transmission. Use AT commands like AT+SAPBR to configure GPRS.

This documentation provides a comprehensive guide to using the SIM800L V2 EVB GSM Module effectively. For further assistance, refer to the manufacturer's datasheet or community forums.