How to Use sim800c development board: Examples, Pinouts, and Specs

The SIM800C Development Board is a compact GSM/GPRS module designed for mobile communication. It enables functionalities such as SMS, voice calls, and data transmission over cellular networks. This module is widely used in IoT applications, remote monitoring systems, and embedded projects requiring cellular connectivity. Its small size, low power consumption, and versatile features make it an excellent choice for developers and hobbyists alike.

• IoT devices requiring cellular connectivity
• Remote monitoring and control systems
• SMS-based alert systems
• GPS tracking and navigation (when paired with a GPS module)
• Voice call-enabled embedded systems
• Data logging and transmission in remote areas

The SIM800C Development Board is built around the SIM800C GSM/GPRS module, offering robust communication capabilities. Below are its key technical details:

• Operating Voltage: 3.4V to 4.4V (typical: 4.0V)
• Power Consumption:
  • Idle mode: ~1mA
  • GSM transmission: ~350mA (peak up to 2A during bursts)
• Frequency Bands: Quad-band GSM (850/900/1800/1900 MHz)
• Data Transmission:
  • GPRS: Class 12, up to 85.6 kbps
• Communication Interfaces:
  • UART (default baud rate: 9600 bps, adjustable)
  • AT command support (3GPP TS 27.007, 27.005)
• SIM Card Support: 1.8V/3V SIM cards
• Operating Temperature: -40°C to +85°C
• Dimensions: ~24mm x 24mm (module size)

The SIM800C Development Board typically includes the following pins for interfacing:

1. Power Supply: Ensure a stable power supply of 4.0V (nominal). Use a capacitor (e.g., 1000µF) near the VCC and GND pins to handle peak current demands during GSM transmission.
2. UART Communication: Connect the TXD and RXD pins to the UART pins of your microcontroller (e.g., Arduino UNO). Use a level shifter if your microcontroller operates at 5V logic levels.
3. SIM Card: Insert a valid SIM card into the SIM card slot. Ensure the SIM card is activated and has sufficient balance for SMS, calls, or data usage.
4. Antenna: Attach a GSM antenna to the module for reliable network connectivity.
5. Initialization: Use AT commands to configure the module. For example, send AT to check communication and AT+CSQ to check signal strength.

• Power Supply: The module can draw up to 2A during GSM bursts. Ensure your power source can handle this.
• Antenna Placement: Place the antenna away from other electronic components to avoid interference.
• UART Baud Rate: The default baud rate is 9600 bps. You can change it using the AT+IPR command.
• Sleep Mode: Use the DTR pin to enable sleep mode for power saving. Pull it low to activate sleep mode.

Below is an example of how to send an SMS using the SIM800C Development Board and an Arduino UNO:

• SIM800C TXD → Arduino RX (Pin 0) (use a level shifter if needed)
• SIM800C RXD → Arduino TX (Pin 1) (use a level shifter if needed)
• SIM800C VCC → 4.0V Power Supply
• SIM800C GND → Arduino GND

#include <SoftwareSerial.h>

// Define RX and TX pins for SoftwareSerial
SoftwareSerial sim800c(10, 11); // RX = Pin 10, TX = Pin 11

void setup() {
  // Initialize serial communication with SIM800C
  sim800c.begin(9600);
  Serial.begin(9600);

  // Wait for the module to initialize
  delay(1000);
  Serial.println("Initializing SIM800C...");

  // Send AT command to check communication
  sim800c.println("AT");
  delay(1000);
  while (sim800c.available()) {
    Serial.write(sim800c.read());
  }

  // Send SMS command
  sim800c.println("AT+CMGF=1"); // Set SMS mode to text
  delay(1000);
  sim800c.println("AT+CMGS=\"+1234567890\""); // Replace with recipient's number
  delay(1000);
  sim800c.println("Hello, this is a test SMS from SIM800C!"); // SMS content
  delay(1000);
  sim800c.write(26); // Send Ctrl+Z to send the SMS
  delay(5000);

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

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

1. Module Not Responding to AT Commands:

   • Ensure the power supply is stable and within the required voltage range.
   • Check the UART connections (TXD and RXD) and ensure they are not swapped.
   • Verify the baud rate (default: 9600 bps).

2. No Network Connectivity:

   • Check the SIM card for proper insertion and activation.
   • Ensure the antenna is securely connected and placed in an area with good signal strength.
   • Use the AT+CSQ command to check signal quality (values above 10 are acceptable).

3. Module Restarts During Operation:

   • This is often caused by insufficient power supply. Use a capacitor (e.g., 1000µF) near the VCC pin to handle peak current demands.

4. SMS Not Sending:

   • Ensure the SIM card has sufficient balance.
   • Verify the recipient's phone number format (e.g., include the country code).

• Q: Can the SIM800C be powered directly from a 5V source?
  A: No, the module requires a voltage range of 3.4V to 4.4V. Use a voltage regulator to step down 5V to 4.0V.

• Q: How do I check the module's firmware version?
  A: Use the AT+GMR command to retrieve the firmware version.

• Q: Can the SIM800C handle voice calls?
  A: Yes, the module supports voice calls. Use the ATD command to dial a number and ATH to hang up.

• Q: What is the maximum data rate for GPRS?
  A: The SIM800C supports GPRS Class 12 with a maximum data rate of 85.6 kbps.