Establish long-distance wireless transmission with RFM75 and ATmega644P

Stay connected without the hassle

Published May 14, 2023

Click board™

ISM Click

Dev. board

EasyAVR v7

Compiler

NECTO Studio

MCU

ATmega644P

Unleash the potential of your solution and get efficient, fast, and reliable wireless communication

Hardware Overview

How does it work?

ISM Click is based on the RFM75, a low-power, high-performance 2.4GHz GFSK transceiver operating in the worldwide ISM frequency band from 2400MHz 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 ultra-low power consumption applications. 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 receiver must be programmed with the same RF channel frequency to communicate, 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. The SPI interface is still active in this mode, and all register values are available by the 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 a 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 only be operated with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using 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.

Features overview

Development board

EasyAVR v7 is the seventh generation of AVR development boards specially designed for the needs of rapid development of embedded applications. It supports a wide range of 16-bit AVR microcontrollers from Microchip and has a broad set of unique functions, such as a powerful onboard mikroProg programmer and In-Circuit debugger over USB. The development board is well organized and designed so that the end-user has all the necessary elements in one place, such as switches, buttons, indicators, connectors, and others. With four different connectors for each port, EasyAVR v7 allows you to connect accessory boards, sensors, and custom electronics more

efficiently than ever. Each part of the EasyAVR v7 development board contains the components necessary for the most efficient operation of the same board. An integrated mikroProg, a fast USB 2.0 programmer with mikroICD hardware In-Circuit Debugger, offers many valuable programming/debugging options and seamless integration with the Mikroe software environment. Besides it also includes a clean and regulated power supply block for the development board. It can use a wide range of external power sources, including an external 12V power supply, 7-12V AC or 9-15V DC via DC connector/screw terminals, and a power source via the USB Type-B (USB-B)

connector. Communication options such as USB-UART and RS-232 are also included, alongside the well-established mikroBUS™ standard, three display options (7-segment, graphical, and character-based LCD), and several different DIP sockets which cover a wide range of 16-bit AVR MCUs. EasyAVR v7 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Microcontroller Overview

MCU Card / MCU

Architecture

AVR

MCU Memory (KB)

Silicon Vendor

Microchip

Pin count

RAM (Bytes)

4096

Used MCU Pins

mikroBUS™ mapper

Data Transmission Indicator

PA7

Chip Enable

PA6

RST

SPI Chip Select

PA5

SPI Clock

PB7

SCK

SPI Data OUT

PB6

MISO

SPI Data IN

PB5

MOSI

Power Supply

3.3V

Ground

GND

Data Reception Indicator

PD4

PWM

Interrupt

PD2

INT

SCL

SDA

Ground

GND

Take a closer look

Click board™ Schematic

Step by step

Project assembly

EasyAVR v7 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the EasyAVR v7 as your development board.

NECTO Output Selection Step Image hardware assembly

In the advanced settings, pay special attention to the Redirect standard output field. By default, it is set to Application output as the method of displaying final results. To show results via a UART terminal, select the “UART” option in that field and click the “SAVE” button. You will be returned to the Compiler field, and now you can move on to the next step by pressing the “NEXT” button.

Buck 22 Click front image hardware assembly

EasyAVR v7 MB 1 - upright/background hardware assembly

NECTO Compiler Selection Step Image hardware assembly

Necto DIP image step 7 hardware assembly

EasyPIC PRO v7a Display Selection Necto Step hardware assembly

Track your results in real time

Application Output

1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.

2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.

3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.

Software Support

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.

Open Source

Code example

The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.

/*!
 * @file main.c
 * @brief Ism Click example
 *
 * # Description
 * This library contains API for the ISM Click driver.
 * This example transmits/receives and processes data from ISM clicks.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes driver and performs the default configuration. 
 *
 * ## Application Task
 * Transmitter/Receiver task depends on uncommented code.
 * Receiver logging each received byte to the UART for data logging,
 * while transmitter send messages every 1 second.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "ism.h"

// Comment out the line below in order to switch the application mode to receiver
#define DEMO_APP_TRANSMITTER

static ism_t ism;
static log_t logger;

static uint8_t demo_message_1[ 9 ] = { 'M', 'i', 'k', 'r', 'o', 'E', 13, 10, 0 };
static uint8_t demo_message_2[ 12 ] = { 'I', 'S', 'M', ' ', 'C', 'l', 'i', 'c', 'k', 13, 10, 0 };

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ism_cfg_t ism_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    ism_cfg_setup( &ism_cfg );
    ISM_MAP_MIKROBUS( ism_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == ism_init( &ism, &ism_cfg ) ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );
        for ( ; ; );
    }

    ism_default_cfg ( &ism );
    Delay_ms ( 100 );
    
#ifdef DEMO_APP_TRANSMITTER
    ism_switch_tx_mode( &ism );
    log_printf( &logger, " Application Mode: Transmitter\r\n" );
#else
    ism_switch_rx_mode( &ism );
    log_printf( &logger, " Application Mode: Receiver\r\n" );
#endif
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
#ifdef DEMO_APP_TRANSMITTER
    ism_transmit_packet( &ism, ISM_CMD_W_TX_PAYLOAD_NOACK, demo_message_1, 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, 12 );
    log_printf( &logger, "  Tx : %s", demo_message_2 );
    Delay_ms ( 1000 );
#else
    uint8_t rx_buf[ ISM_MAX_PACKET_LEN ] = { 0 };

    ism_receive_packet( &ism, &rx_buf[ 0 ] );

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

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

/*!
 * @file main.c
 * @brief Ism Click example
 *
 * # Description
 * This library contains API for the ISM Click driver.
 * This example transmits/receives and processes data from ISM clicks.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes driver and performs the default configuration. 
 *
 * ## Application Task
 * Transmitter/Receiver task depends on uncommented code.
 * Receiver logging each received byte to the UART for data logging,
 * while transmitter send messages every 1 second.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "ism.h"

// Comment out the line below in order to switch the application mode to receiver
#define DEMO_APP_TRANSMITTER

static ism_t ism;
static log_t logger;

static uint8_t demo_message_1[ 9 ] = { 'M', 'i', 'k', 'r', 'o', 'E', 13, 10, 0 };
static uint8_t demo_message_2[ 12 ] = { 'I', 'S', 'M', ' ', 'C', 'l', 'i', 'c', 'k', 13, 10, 0 };

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ism_cfg_t ism_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    ism_cfg_setup( &ism_cfg );
    ISM_MAP_MIKROBUS( ism_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == ism_init( &ism, &ism_cfg ) ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );
        for ( ; ; );
    }

    ism_default_cfg ( &ism );
    Delay_ms ( 100 );
    
#ifdef DEMO_APP_TRANSMITTER
    ism_switch_tx_mode( &ism );
    log_printf( &logger, " Application Mode: Transmitter\r\n" );
#else
    ism_switch_rx_mode( &ism );
    log_printf( &logger, " Application Mode: Receiver\r\n" );
#endif
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
#ifdef DEMO_APP_TRANSMITTER
    ism_transmit_packet( &ism, ISM_CMD_W_TX_PAYLOAD_NOACK, demo_message_1, 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, 12 );
    log_printf( &logger, "  Tx : %s", demo_message_2 );
    Delay_ms ( 1000 );
#else
    uint8_t rx_buf[ ISM_MAX_PACKET_LEN ] = { 0 };

    ism_receive_packet( &ism, &rx_buf[ 0 ] );

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

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END

/*!
 * @file main.c
 * @brief Ism Click example
 *
 * # Description
 * This library contains API for the ISM Click driver.
 * This example transmits/receives and processes data from ISM clicks.
 *
 * The demo application is composed of two sections :
 *
 * ## Application Init
 * Initializes driver and performs the default configuration. 
 *
 * ## Application Task
 * Transmitter/Receiver task depends on uncommented code.
 * Receiver logging each received byte to the UART for data logging,
 * while transmitter send messages every 1 second.
 *
 * @author Nenad Filipovic
 *
 */

#include "board.h"
#include "log.h"
#include "ism.h"

// Comment out the line below in order to switch the application mode to receiver
#define DEMO_APP_TRANSMITTER

static ism_t ism;
static log_t logger;

static uint8_t demo_message_1[ 9 ] = { 'M', 'i', 'k', 'r', 'o', 'E', 13, 10, 0 };
static uint8_t demo_message_2[ 12 ] = { 'I', 'S', 'M', ' ', 'C', 'l', 'i', 'c', 'k', 13, 10, 0 };

void application_init ( void ) 
{
    log_cfg_t log_cfg;  /**< Logger config object. */
    ism_cfg_t ism_cfg;  /**< Click config object. */

    /** 
     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
     */
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, " Application Init " );

    // Click initialization.
    ism_cfg_setup( &ism_cfg );
    ISM_MAP_MIKROBUS( ism_cfg, MIKROBUS_1 );
    if ( SPI_MASTER_ERROR == ism_init( &ism, &ism_cfg ) ) 
    {
        log_error( &logger, " Application Init Error. " );
        log_info( &logger, " Please, run program again... " );
        for ( ; ; );
    }

    ism_default_cfg ( &ism );
    Delay_ms ( 100 );
    
#ifdef DEMO_APP_TRANSMITTER
    ism_switch_tx_mode( &ism );
    log_printf( &logger, " Application Mode: Transmitter\r\n" );
#else
    ism_switch_rx_mode( &ism );
    log_printf( &logger, " Application Mode: Receiver\r\n" );
#endif
    log_info( &logger, " Application Task " );
}

void application_task ( void ) 
{
#ifdef DEMO_APP_TRANSMITTER
    ism_transmit_packet( &ism, ISM_CMD_W_TX_PAYLOAD_NOACK, demo_message_1, 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, 12 );
    log_printf( &logger, "  Tx : %s", demo_message_2 );
    Delay_ms ( 1000 );
#else
    uint8_t rx_buf[ ISM_MAX_PACKET_LEN ] = { 0 };

    ism_receive_packet( &ism, &rx_buf[ 0 ] );

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

int main ( void ) 
{
    /* Do not remove this line or clock might not be set correctly. */
    #ifdef PREINIT_SUPPORTED
    preinit();
    #endif
    
    application_init( );
    
    for ( ; ; ) 
    {
        application_task( );
    }

    return 0;
}

// ------------------------------------------------------------------------ END