GSM Click

How does it work?

GSM Click is based on the GL865-QUAD, a GSM/GPRS embedded module from Telit. The GL865-QUAD module is GSM/GPRS protocol stack 3GPP Release 4 compliant and compliant with the eCall EU Directive. It supports quad-band GSM/GPRS and covers frequencies of 850/900/1800/1900 MHz, allowing it to be used worldwide. A wide range of communication protocols and connectivity options, coupled with the embedded Phyton Script interpreter and Telit’s simple AT command interface via the UART bus, make this Click board™ a complete solution for a wide range of M2M applications. The module consists of several internal blocks or sections, such as the antenna switching section, RF transceiver section, memory, power management, and most importantly – the cellular baseband processor.

The micro-SIM card holder on the back of the Click board™ is used to install a micro-SIM card. This device cannot be used without a valid SIM card, which allows connection to the cellular network. Both 1.8V and 3V SIM card types are supported. You will also need an appropriate SMA antenna, which MIKROE also offers. There are two LEDs: TXD, which indicates transmission activity/SIM card presence, and STAT, which indicates the device status in several blinking patterns. As for RXD LED, it might require configuration of the GPIO pins; however, the provided click library offers functions that initialize the module properly and allow easy communication with the GSM click.

The GL865-QUAD offers extensive audio features, including Half rate, full rate, enhanced full rate and adaptive multi-rate voice codecs, superior echo cancellation and noise reduction, multiple pre-programmed audio profiles, fully configurable with the AT commands, and DTMF tone generation. The audio section is integrated into the module and requires only a few external components. The headset can be connected via the 4-pole 3.5mm audio jack. As mentioned before, this module features an embedded Phyton Script interpreter. It allows scripts written in Phyton to be loaded and provides 1.9 MB of non-volatile memory for the user scripts and 1 MB of RAM for the Python engine.

GSM Click uses a standard 2-Wire UART interface to communicate with the host MCU with commonly used UART RX and TX pins. Additionally, the GSM Click offers the UART flow control RTS and CTS pins. UART interface supports baud rates from 300 up to 115200bps with automatic baud rate detection. The voltage level translation is entrusted to the TXB0106, a 6-bit bidirectional level-shifting voltage translator from Texas Instruments. You can reset the GSM module over the RST pin. The device power-on status can be monitored over the PWR pin. A nice feature is jammer detection, available on the GP2 pin.

It is recommended to follow a certain procedure when powering down the GSM click. Data corruption is possible if the module is turned off abruptly while being operated. It halts the AT command to stop the system before powering it down, which should be issued (AT#SYSHALT).

This Click board™ can operate with either 3.3V or 5V logic voltage levels selected via the I/O Level jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on GSM click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Power-On Monitor	PWR	1	AN	PWM	16	GP2	Jammer Detect
Reset	RST	2	RST	INT	15	CTS	UART CTS
UART RTS	RTS	3	CS	RX	14	TX	UART TX
	NC	4	SCK	TX	13	RX	UART RX
	NC	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
Power Supply	3V3	7	3.3V	5V	10	5V	Power Supply
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

GSM Click electrical specifications

Software Support

We provide a library for the GSM Click as well as a demo application (example), developed using MIKROE compilers. The demo can run on all the main MIKROE development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for GSM Click driver.

Key functions

• Enables or disables module power.

• Generic write function.

• Command function.

Example Description

This example reads and processes data from GSM clicks.

 void application_task ( void ) 
 { 
      gsm_process( ); 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Gsm

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all MIKROE compilers.

mikroSDK

This Click board™ is supported with mikroSDK – MIKROE Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.