SIM800L GPRS GSM Module Core Board Quad-band TTL Serial Port

Specifications:

• Supply Voltage: 3.4V – 4.4V DC (4.0V recommended)
• Peak Current Draw: Up to 2A (during transmission bursts)
• Standby Current: < 2mA
• Supported Frequencies: Quad-band 850 / 900 / 1800 / 1900 MHz
• SIM Card Slot: Micro SIM (Push-Pull type)
• Communication Interface: TTL Serial (UART, 2.8V logic level)
• Baud Rate Support: Auto-baud (1200 bps to 115200 bps)
• Antenna Options: Onboard spring antenna included; IPEX/U.FL connector available
• Operating Temperature: -40°C to +85°C
• Status LED Indicator: Ringing/Net status blinks slowly when logged into a network

Unlock New Capabilities

• Past Projects If you've already experimented with Wi-Fi modules like the ESP8266 or Bluetooth boards for localized communication, you know how to send data wirelessly. However, you've likely hit the limit of local networks—once your project leaves the building, it loses connection. Now, you are ready to cut the cord completely and move into wide-area cellular communication.
• Feature Upgrade The SIM800L module unlocks true remote IoT functionality. It enables your projects to send SMS alerts when a sensor triggers, make or receive automated voice calls, and upload GPS coordinates or environmental data to cloud servers via GPRS. It is the perfect backbone for remote weather stations, vehicle tracking systems, smart agriculture monitors, and emergency panic buttons that need to work miles away from any Wi-Fi router.
• Effort Level & Minimum Hardware
• Effort Level: Intermediate

Minimum hardware to get started:

• Microcontroller (Arduino/ESP32) — to send AT commands to the SIM800L via serial communication.
• Dedicated Power Supply (LM2596 DC-DC Buck Converter or 3.7V LiPo Battery) — strictly required. The SIM800L needs 3.4V to 4.4V and draws up to 2A during transmission bursts. A standard Arduino 5V or 3.3V pin cannot provide this current and will cause the module to continuously reboot.
• Micro SIM Card — with an active 2G network plan (ensure 2G/GSM is supported by your carrier in your area).
• Logic Level Converter / Voltage Divider Resistors — to safely step down the 5V TX signal from an Arduino to the 2.8V RX pin on the SIM800L.

Included in the Box:

• 1×SIM800L GPRS GSM Module Core Board Quad-band TTL Serial Port

Frequently Asked Questions

• Is the SIM800L compatible with Arduino and ESP32?
  Yes, it can communicate with almost any microcontroller using software serial or hardware serial UART pins.
• Can I use this module with a Raspberry Pi?
  Yes, you can connect it to the Raspberry Pi UART pins, provided you power the module from an external high-current supply and not the Pi itself.
• Does this module work with 4G or 5G SIM cards?
  It physically accepts 4G SIM cards, but the module only contains a 2G radio; ensure your cellular carrier still supports 2G networks in your deployment area.
• Do I need a specific microcontroller to use this?
  No, any device or microcontroller that supports basic TTL serial communication can control the module via standard AT commands.
• Can I power the SIM800L directly from an Arduino 5V pin?
  No, the Arduino cannot provide the 2A peak current required, and the 5V level will permanently damage the module's power circuitry.
• What happens if I power it with exactly 3.3V?
  3.3V is below the recommended 3.4V–4.4V operating range and will typically cause the module to constantly reboot while searching for a network.
• Why is a buck converter highly recommended for this board?
  A buck converter like the LM2596 can safely step down a higher voltage source to exactly 4.0V while delivering the necessary 2 Amps of peak current.
• What do the TX and RX pins do on the SIM800L?
  They are used to send and receive serial AT commands and data payloads between the cellular module and your microcontroller.
• Do I absolutely need a logic level shifter for the RX pin?
  Yes, if your microcontroller operates at 5V logic (like an Arduino Uno), you must step the TX signal down to 2.8V to prevent damaging the SIM800L RX pin.
• What is the purpose of the VDD pin found on some versions of this board?
  It is sometimes used to match the TTL logic level of the host microcontroller, but you should refer to your specific board revision's schematic for exact usage.
• Do I have to write AT commands manually in my code?
  You can send raw AT commands directly, but using established libraries like Adafruit FONA simplifies the coding process significantly.
• How do I test if the module is responding before writing full code?
  You can use an Arduino programmed as a simple USB-to-Serial passthrough, open the Serial Monitor, and type "AT" to see if the module replies with "OK".
• Where can I find example code for sending an SMS?
  Search for "Arduino SIM800L SMS tutorial" to find pre-written sketches where you simply insert your destination phone number and message string.
• Why is the onboard LED blinking rapidly non-stop?
  A rapid blink (about once every second) means the module is powered on but cannot find a cellular network or register to a cell tower.