Examples and demos

Various examples are provided for fast library evaluation on embedded systems. These are prepared and maintained for 2 platforms, but could be easily extended to more platforms:


Library is platform independent and can be used on any platform.

Example architectures

There are many platforms available today on a market, however supporting them all would be tough task for single person. Therefore it has been decided to support (for purpose of examples) 2 platforms only, WIN32 and STM32.


Examples for WIN32 are prepared as Visual Studio Community projects. You can directly open project in the IDE, compile & debug.

Application opens COM port, set in the low-level driver. External USB to UART converter (FTDI-like device) is necessary in order to connect to GSM device.


GSM device is connected with USB to UART converter only by RX and TX pins.

Device driver is located in /lwgsm/src/system/lwgsm_ll_win32.c


Embedded market is supported by many vendors and STMicroelectronics is, with their STM32 series of microcontrollers, one of the most important players. There are numerous amount of examples and topics related to this architecture.

Examples for STM32 are natively supported with STM32CubeIDE, an official development IDE from STMicroelectronics.

You can run examples on one of official development boards, available in repository examples.

Supported development boards

Board name

GSM settings

Debug settings
















Pins to connect with GSM device:

  • MTX: MCU TX pin, connected to GSM RX pin

  • MRX: MCU RX pin, connected to GSM TX pin

  • RST: MCU output pin to control reset state of GSM device

Other pins are for your information and are used for debugging purposes on board.

  • MDTX: MCU Debug TX pin, connected via on-board ST-Link to PC

  • MDRX: MCU Debug RX pin, connected via on-board ST-Link to PC

  • Baudrate is always set to 921600 bauds

Examples list

Here is a list of all examples coming with this library.


Examples are located in /examples/ folder in downloaded package. Check Download library section to get your package.


Do not forget to set PIN & PUK codes of your SIM card before running any of examples. Open /snippets/sim_manager.c and update pin_code and puk_code variables.

Device info

Simple example which prints basic device information:

  • Device Manufacturer

  • Device Model

  • Device serial number

  • Device revision number


Similar to MQTT Client examples, but it uses separate thread to process events in blocking mode. Application does not use events to process data, rather it uses blocking API to receive packets

Netconn client

Netconn client is based on sequential API. It starts connection to server, sends initial request and then waits to receive data.

Processing is in separate thread and fully sequential, no callbacks or events.


Call example answers received call. If GSM device supports calls and has microphone/speaker connected to module itself, it can simply communicate over voice.

Call & SMS

This example shows how to receive a call and send reply with SMS. When application receives call, it hangs-up immediately and sends back SMS asking caller to send SMS instead.

When application receives SMS, it will send same SMS content back to the sender’s number.

SMS Send receive

It demonstrates sending and receiving SMS either in events or using thread processing.