IOT

What is a SIM800L GPRS/GSM Module?

If you’re an Electronics enthusiast, you might be interested in experimenting with cell phone connections. I’ve seen several projects that are activated by SMS or voice instructions, but the majority of them use ancient phones. So here we are seeking the help of the SIM800L GPRS Module for this Purpose. In this blog, we will be discussing the basics of the SIM800L GPRS Module in detail.

SIM800L GSM/GPRS module designed as a miniature GSM modem can be integrated into a great number of IoT projects. This SIM800L GSM/GPRS module performs a similar function as a normal cell phone can. It can SMS text messages, make or receive phone calls, connect to the internet through GPRS, TCP/IP, and more. Moreover, the module supports quad-band GSM/GPRS network, which indicates that it works pretty much anywhere in the world.

SIM800L GSM/GPRS module-In Detail

SIM800L GSM cellular chip from SimCom is the heart of this module. It supports the UART protocol to communicate with the microcontroller at a baud rate ranging from 1200bps to 115200bps with Auto-Baud detection. All the necessary data pins of the SIM800L GSM chip are broken out to 0.1″ pitch headers. The module chip operates at a voltage range from 3.4V to 4.4V, making it an ideal solution for direct LiPo battery supply. This makes wide usage for embedding into projects without a lot of space.

SIM800L Module Hardware Overview - LED Indicator, u.fl Connector, Helical Antenna

An external antenna is used for any kind of voice or data communications as well as some SIM commands. This module usually comes with a Helical Antenna soldered directly to the NET pin on PCB. Else a 3dBi GSM antenna along with a U.FL to SMA adapter is highly recommended for better performance.  It also consists of an onboard U.FL connector facility to keep the antenna away from the board when necessary.

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SIM800L Module Hardware Overview - Micro SIM Socket, Direction to Insert SIM

A SIM socket on the back of the module helps the 2G micro SIM card work perfectly. Inserting sim incorrect direction normally engraved on the surface of the SIM socket. This module measures only 1 inch² but packs a surprising amount of features into its little frame. Some of the features are listed below:

Features

  • Chip: SIM800L
  • Supports Quad-band: GSM850, EGSM900, DCS1800, and PCS1900
  • Operating voltage: 3.7V -4.2V
  • Current: 2A
  • Quad-band (850/900/1800/1900MHz) supports
  • Connect onto any global GSM network with any 2G SIM
  • Make and receive voice calls using an external 8Ω speaker & electret microphone
  • Send and receive SMS messages
  • Send and receive GPRS data (TCP/IP, HTTP, etc.)
  • Scan and receive FM radio broadcasts
  • Transmit Power:
    • Class 4 (2W) for GSM850
    • Class 1 (1W) for DCS1800
  • Serial-based AT Command Set
  • FL connectors for cell antennae
  • Searches for network and login automatically
  • AT command interface with auto baud detection
  • Lead-out buzzer and vibration motor control port
  • Interface: UART (max 2.8V, serial interface)
  • Command support: 3G PP TS 27. 007, 27. 005 and SIMCOM enhanced AT commands
  • Sim Card Slot: Micro SIM
  • Temperature range: -40℃ to 85℃
  • LED Status Indicators

The status of your cellular network is indicated by an LED on the top right side of the SIM800L Cellular Module. It’ll blink at different rates depending on what condition it’s in:

When blinked for every 1s Indicates the module is running but no connections are made to any cellular network. 

Netlight LED Blinking Finding Network Connection
Blink every 1s

Whereas blinking for every 2s resembles the requested GPRS data connection is active.

Netlight LED Blinking Active GPRS Connection
Blink every 2s

Finally, blinking every 3s means module has made contact with the cellular network & can send/receive voice and SMS.

Netlight LED Blinking Network Connection Established
Blink every 3s

  • Selecting Antenna

To utilize the module for voice or data communications, as well as some SIM instructions, you’ll need an antenna. As a result, choosing an antenna could be critical. You may add an antenna to your SIM800L module in two ways.

The first is a helical GSM antenna, which normally comes with the module and connects to the PCB’s NET pin. This antenna is ideal for applications that require minimal area yet struggle to maintain communication, particularly if the project is being carried out indoors.

SIM800L GSM Module with Helical Antenna

The second option is to use any 3dBi GSM antenna with a U.FL to SMA adapter. This antenna snaps into the little u.fl connector on the top-left corner of the module. This sort of antenna performs better and allows you to put your module inside a metal case as long as the antenna is outside.

SIM800L GSM Module with 2dBi Duck Antenna
  • Supplying Power for SIM800L module

Providing enough power to the SIM800L module is one of the most crucial aspects of getting it to work.

The SIM800L can be a power-hungry device depending on which condition it’s in. During transmission bursts, the module’s maximum current draw is roughly 2A. During phone calls, it may demand roughly 216mA, and during network transmissions, it may require around 80mA. 

. This chart from the datasheet summarizes what you may expect:

MODEFREQUENCYCURRENT CONSUMPTION
Power down60uA
Sleep mode1mA
Stand by18mA
CallGSM850199mA
EGSM900216mA
DCS1800146mA
PCS1900131mA
GPRS453mA
Transmission Burst2A

Since the SIM800L module doesn’t come with an onboard voltage regulator, an external power supply adjusted to a voltage between 3.4V to 4.4V (Ideal 4.1V) is required. The power supply must also be capable of supplying 2A of surge current, or the module will continue to shut down. Here are some choices to consider when it comes to properly powering your GSM module.

  • 3.7v Li-Po Battery (Recommended)

One of the best things about Li-Po batteries is that their voltage is usually between 3.7 and 4.2 volts, which is ideal for the SIM800L Module. Any Lithium-ion/polymer battery with a capacity of 1200mAh or more is ideal since it can maintain the optimum voltage range even during 2 Amp surges.

1200mAh LiPo Battery
  • DC-DC Buck Converter

Any DC-DC buck converter with a current rating of 2A, such as the LM2596, would work. These are far more efficient than LM317 or LM338 linear voltage regulators.

LM2596 DC-DC Buck Converter

Warning: GND should never be disconnected before VCC, and VCC should always be connected before GND. Otherwise, the low voltage serial pins will be used as ground, and the module would be destroyed instantaneously.

SIM800L GSM Module Pinout

The SIM800L module has a total of 12 pins that interface it to the outside world. The connections are as follows:

SIM800L GSM Module Pinout
  • NET: This is a pin where you can solder Helical Antenna provided along with the module.
  • VCC: The module is powered by VCC. This might be anywhere between 3.4 and 4.4 volts. Remember that attaching it to the 5V pin will most certainly cause your module to fail! It doesn’t even operate at 3.3 volts! External power sources such as Li-Po batteries or 3.7V 2A DC-DC buck converters could be used.
  • RST (Reset): Hard reset pin. Pull this pin low for 100ms to execute a hard reset if you absolutely got the module in a poor space.
  • RxD (Receiver) pin: Used for serial communication.
  • TxD (Transmitter) pin: Used for serial communication.
  • GND: This is the Ground Pin and needs to be connected to the GND pin on the Arduino.
  • RING: This pin acts as a Ring Indicator. It is basically the ‘interrupt’ out pin from the module. When a call is received, it is set to high by default and pulses low for 120 milliseconds. When an SMS is received, it can also be set to pulse.
  • DTR: Sleep mode is activated or deactivated via the DTR pin. Pulling it HIGH disables serial connectivity and puts the module into sleep mode. The module will be awakened if you pull it LOW.
  • MIC±/; This is a differential microphone input. The two microphone pins can be connected directly to these pins.
  • SPK±:The SPK speaker interface is a differential speaker interface. A speaker’s two pins can be connected directly to these two pins.

Advantages of SIM800L GPRS Module

  • Easy to develop and a popular choice among both hobbyists and product developers
  • Extensive features including voice calls, SMS, and internet access
  • Small size is ideal for portable products and wearable tech
  • Very affordable module from a Chinese manufacturer
  • The manufacturer of the SIM800, SimCom, also offers numerous other communication modules including the SIM868 which includes built-in GPS functionality.

Disadvantages of SIM800L GPRS Module

  • Older 2G technology with limited data speeds (GSM/GPRS)
  • Not necessarily the smallest, lowest power, or highest performance cellular module available. 

Conclusion

Hope this blog helps you to understand the basics of the SIM800L GPRS Module, Its Advantages, and its Disadvantages. We, MATHA ELECTRONICS will come back with more informative blogs.

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