SIM800L Micro SIM GSM / GPRS Module Board with Antenna

Description

Key Features & Specifications

• Network / Frequency: Quad-Band GSM/GPRS (850 / 900 / 1800 / 1900 MHz) — works globally on standard 2G cellular networks.

• Operating Voltage: 3.4V to 4.4V DC (Nominal: 3.7V–4.0V).

  • Important: Do NOT power it directly with 5V or 3.3V from an Arduino or ESP32 pin, as it can damage the board or cause power dropouts.

• Current Consumption:

  • Idle / Sleep: ~1 mA – 10 mA

  • Transmit Peak / Burst Current: Up to 2A during network signal bursts.

• SIM Card Slot: Micro-SIM slot.

• Interface / Communication: UART (TTL Serial) at logic levels between 2.8V and 5V (use a logic level converter or resistor voltage divider when interfacing with 5V microcontrollers like an Arduino Uno).

• Core Functions: SMS (Send/Receive), Voice Calls, GPRS Data transmission (HTTP/MQTT/TCP/UDP).

Pinout Reference

Important Usage Tips & Troubleshooting

1. Power Supply Requirements:

   • Power stability is the #1 issue with the SIM800L. If the module repeatedly resets or fails to connect to the network (LED blinks rapidly non-stop), it is almost always due to an inadequate power source.

   • A single 18650 Li-ion battery (3.7V) or a 5V power supply stepped down using an LM2596 or Buck converter set to 4.0V works best. Adding a 1000 µF capacitor across VCC and GND near the module helps smooth out power spikes.

2. Status LED Indicators:

   • Blinking every 1 second: Searching for network / No signal.

   • Blinking every 3 seconds: Connected to cellular network successfully.

   • Blinking fast (800ms): GPRS network connected.

3. 2G Network Availability:

   • Ensure cellular carriers in your region still support 2G (GSM) connectivity, as several global carriers have sunsetted or are phasing out 2G in favor of LTE / 4G / 5G.

Basic AT Commands for Testing

Connect via Serial Terminal at 9600 baud:

AT              --> Returns "OK" (Tests communication)
AT+CPIN?        --> Returns "+CPIN: READY" (Checks if SIM card is detected)
AT+CSQ          --> Returns signal quality (e.g., +CSQ: 18, 99)
AT+CREG?        --> Returns "+CREG: 0,1" or "+C