ISM Click

How does it work?

ISM Click as its foundation uses the RFM75, a low-power, high-performance 2.4GHz GFSK transceiver operating in the worldwide ISM frequency band from 2400MHz up to 2527MHz from RF Solutions. The RFM75 operates in TDD mode, either as a transmitter or as a receiver. Burst mode transmission and up to 2Mbps air data rate make it suitable for applications requiring ultra-low power consumption. The embedded packet processing engines enable their entire operation with a simple MCU as a radio system. Auto re-transmission and auto acknowledge giving reliable link without any MCU interference.

A transmitter and a receiver must be programmed with the same RF channel frequency to communicate with each other supporting a programmable air data rate of 250Kbps, 1Mbps, or 2Mbps. The RF channel frequency determines the center of the channel used by RFM75. The RF_CH register, in register bank 0, sets the frequency according to the following formula F0= 2400 + RF_CH (MHz), where the resolution of the RF channel frequency is 1MHz.

ISM Click communicates with MCU using the standard SPI serial interface that operates at clock rates up to 8 MHz. In power-down mode, RFM75 is in Sleep mode with minimal current consumption. SPI interface is still active in this mode, and all register values are available by SPI interface. This Click board™ also has a yellow LED indicator routed on the INT pin of the mikroBUS™ socket (provide the user with feedback after a successfully received package) and chip-enable function routed on the RST pin of the mikroBUS™ which activates TX or RX mode of the RFM75. Besides, it also has two additional LED indicators, a red and blue LED routed on the AN and PWM pins of the mikroBUS™ socket. The user can use it for visual indication when sending or receiving data.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before use with MCUs with different logic levels. However, the Click board™ comes equipped with a library containing 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 ISM Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Data Transmission Indicator	TL	1	AN	PWM	16	RL	Data Reception Indicator
Chip Enable	CE	2	RST	INT	15	IRQ	Interrupt
SPI Chip Select	CS	3	CS	RX	14	NC
SPI Clock	SCK	4	SCK	TX	13	NC
SPI Data OUT	SDO	5	MISO	SCL	12	NC
SPI Data IN	SDI	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

ISM Click electrical specifications

Software Support

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

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

Library Description

This library contains API for ISM Click driver.

Key functions:

• ism_cfg_setup - Config Object Initialization function.
• ism_init - Initialization function.
• ism_default_cfg - Click Default Configuration function.

Examples description

This library contains API for the ISM Click driver. This example transmits/receives and processes data from ISM clicks. The library initializes and defines the UART bus drivers to transmit or receive data.

The demo application is composed of two sections :

void application_task ( void ) {
    #ifdef RECEIVER
        uint8_t rx_buf[ ISM_MAX_PACKET_LEN ] = { 0 };

        ism_receive_packet( &ism, &rx_buf[ 0 ] );
    
        if ( rx_buf[ 0 ] != 0 ) {
            log_printf( &logger, "  Rx : %s", rx_buf );
        }
    #endif

    #ifdef TRANSMITTER
        ism_transmit_packet( &ism, ISM_CMD_W_TX_PAYLOAD_NOACK, &demo_message_1[ 0 ], 9 );
        log_printf( &logger, "  Tx : %s", demo_message_1 );
        Delay_ms( 1000 );
    
        ism_transmit_packet( &ism, ISM_CMD_W_TX_PAYLOAD_NOACK, &demo_message_2[ 0 ], 12 );
        log_printf( &logger, "  Tx : %s", demo_message_2 );
        Delay_ms( 1000 );
    #endif
}

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

Other mikroE Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.Ism

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. The terminal available in all MikroElektronika compilers, or any other terminal application of your choice, can be used to read the message.

mikroSDK

This Click board™ is supported with mikroSDK - MikroElektronika 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.