Intermediate
30 min

Create an easy-to-use/drop-in solution based on BLE 4.2 with RN4870 and ATmega328P

Simplify connectivity

RN4870 click with Arduino UNO Rev3

Published Feb 14, 2024

Click board™

RN4870 click

Dev. board

Arduino UNO Rev3

Compiler

NECTO Studio

MCU

ATmega328P

Enable Bluetooth Low Energy connectivity for data exchange between devices.

A

A

Hardware Overview

How does it work?

RN4870 Click is based on the RN4870, a Bluetooth® 4.2 low-energy module from Microchip. The Click is designed to run on a 3.3V power supply. It uses ASCII Command Interface over UART for communication with the target microcontroller, with additional functionality provided by the following pins on the mikroBUS™ line: PWM, INT, RST, CS. The RN4080 module from Microchip offers a complete solution to implement

Bluetooth 4.2 Low Energy connectivity. The host microcontroller can dynamically configure all products in the RN series with a few simple ASCII commands. The RN4870 supports peripheral and central Generic Access Profile (GAP) roles, actively scanning for other connectable devices instead of waiting for incoming connection requests. The peripherals are usually small, low-power devices that broadcast information to the central

device, like sensors and monitors. The central device can communicate with multiple peripherals. It also supports Remote Command mode, allowing a remote device to access Command mode remotely via Bluetooth. The module contains an integral ceramic chip antenna.

RN4870 Click hardware overview image

Features overview

Development board

Arduino UNO is a versatile microcontroller board built around the ATmega328P chip. It offers extensive connectivity options for various projects, featuring 14 digital input/output pins, six of which are PWM-capable, along with six analog inputs. Its core components include a 16MHz ceramic resonator, a USB connection, a power jack, an

ICSP header, and a reset button, providing everything necessary to power and program the board. The Uno is ready to go, whether connected to a computer via USB or powered by an AC-to-DC adapter or battery. As the first USB Arduino board, it serves as the benchmark for the Arduino platform, with "Uno" symbolizing its status as the

first in a series. This name choice, meaning "one" in Italian, commemorates the launch of Arduino Software (IDE) 1.0. Initially introduced alongside version 1.0 of the Arduino Software (IDE), the Uno has since become the foundational model for subsequent Arduino releases, embodying the platform's evolution.

Arduino UNO Rev3 double side image

Microcontroller Overview

MCU Card / MCU

default

Architecture

AVR

MCU Memory (KB)

32

Silicon Vendor

Microchip

Pin count

28

RAM (Bytes)

2048

You complete me!

Accessories

Click Shield for Arduino UNO has two proprietary mikroBUS™ sockets, allowing all the Click board™ devices to be interfaced with the Arduino UNO board without effort. The Arduino Uno, a microcontroller board based on the ATmega328P, provides an affordable and flexible way for users to try out new concepts and build prototypes with the ATmega328P microcontroller from various combinations of performance, power consumption, and features. The Arduino Uno has 14 digital input/output pins (of which six can be used as PWM outputs), six analog inputs, a 16 MHz ceramic resonator (CSTCE16M0V53-R0), a USB connection, a power jack, an ICSP header, and reset button. Most of the ATmega328P microcontroller pins are brought to the IO pins on the left and right edge of the board, which are then connected to two existing mikroBUS™ sockets. This Click Shield also has several switches that perform functions such as selecting the logic levels of analog signals on mikroBUS™ sockets and selecting logic voltage levels of the mikroBUS™ sockets themselves. Besides, the user is offered the possibility of using any Click board™ with the help of existing bidirectional level-shifting voltage translators, regardless of whether the Click board™ operates at a 3.3V or 5V logic voltage level. Once you connect the Arduino UNO board with our Click Shield for Arduino UNO, you can access hundreds of Click boards™, working with 3.3V or 5V logic voltage levels.

Click Shield for Arduino UNO accessories 1 image

Used MCU Pins

mikroBUS™ mapper

NC
NC
AN
Module Reset
PD2
RST
UART RTS
PB2
CS
NC
NC
SCK
NC
NC
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
PWM Signal
PD6
PWM
UART CTS
PC3
INT
UART TX
PD0
TX
UART RX
PD1
RX
General-Purpose I/O
PC5
SCL
General-Purpose I/O
PC4
SDA
NC
NC
5V
Ground
GND
GND
1

Take a closer look

Click board™ Schematic

RN4870 click Schematic schematic

Step by step

Project assembly

Click Shield for Arduino UNO front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Arduino UNO Rev3 as your development board.

Click Shield for Arduino UNO front image hardware assembly
Arduino UNO Rev3 front image hardware assembly
Barometer 13 Click front image hardware assembly
Prog-cut hardware assembly
Arduino UNO Rev3 MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
Necto image step 5 hardware assembly
Necto image step 6 hardware assembly
Arduino UNO MCU Step hardware assembly
Necto No Display image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Debug Image 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 RN4870 Click driver.

Key functions:

  • rn4870_read - This function gets message from 'void rn4870_receive function if flag was set

  • rn4870_receive - This function receives character by waits for '#' - character to start parsing message, waits for '*' - character to stop parsing message and sets flag if whole and properly formated message is received

  • rn4870_connect - This function connects to slave device with desired register address by secures the connection and entering data stream mode

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 
 * \brief Rn4870 Click example
 * 
 * # Description
 * This example reads and processes data from RN4870 clicks.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * Initializes UART driver. Initializes device and parser.
 * 
 * ## Application Task  
 * If 'MASTER' - connects to 'SLAVE', sends message and disconnects. If 'SLAVE' - waits for connect request 
 * and message from 'MASTER' and LOGs received message.
 * 
 * ## Additional Function
 * - rn4870_process ( ) - The general process of collecting presponce 
 *                                   that sends a module.
 * 
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "rn4870.h"
#include "string.h"

#define PROCESS_COUNTER 10
#define PROCESS_RX_BUFFER_SIZE 500
#define PROCESS_PARSER_BUFFER_SIZE 500

// ------------------------------------------------------------------ VARIABLES

// #define DEMO_APP_RECEIVER
#define DEMO_APP_TRANSMITER

static rn4870_t rn4870;
static log_t logger;

uint8_t RN4870_ADDR_MASTER[ 13 ] = {'D', 'F', '0', '0', '0', '0', '0', '6', '8', '7', '9', '0'};
uint8_t RN4870_ADDR_SLAVE[ 13 ] = {'D', 'F', '1', '1', '1', '1', '1', '6', '8', '7', '9', '0'};
uint8_t message_payload[ 17 ] = {'M', 'i', 'k', 'r', 'o', 'E', 'l', 'e', 'k', 't', 'r', 'o', 'n', 'i', 'k', 'a'};

uint8_t dev_type;
uint8_t receive_buffer[ 255 ];
uint8_t msg_flag = 0;
char *ptr;

// ------------------------------------------------------- ADDITIONAL FUNCTIONS

static void rn4870_process ( void )
{
    int32_t rsp_size;
    
    char uart_rx_buffer[ PROCESS_RX_BUFFER_SIZE ] = { 0 };
    uint8_t check_buf_cnt;
    

    rsp_size = rn4870_generic_read( &rn4870, &uart_rx_buffer, PROCESS_RX_BUFFER_SIZE );

    if ( rsp_size > 0 )
    {  
        // Validation of the received data
        for ( check_buf_cnt = 0; check_buf_cnt < rsp_size; check_buf_cnt++ )
        {
            rn4870_receive( &rn4870, uart_rx_buffer[ check_buf_cnt ] );
        }
    }
}

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
{
    log_cfg_t log_cfg;
    rn4870_cfg_t cfg;

    /** 
     * 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.

    rn4870_cfg_setup( &cfg );
    RN4870_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    rn4870_init( &rn4870, &cfg );
    Delay_ms( 100 );
    
    dev_type = RN4870_DEVICETYPE_MASTER;

#ifdef DEMO_APP_TRANSMITER
    log_info( &logger, "RN4870 DEVICE TYPE MASTER" );
    rn4870_initialize( &rn4870, &RN4870_ADDR_MASTER[ 0 ] );
#endif
#ifdef DEMO_APP_RECEIVER
    log_info( &logger, "RN4870 DEVICE TYPE SLAVE" );
    rn4870_initialize( &rn4870, &RN4870_ADDR_SLAVE[ 0 ] );
    ptr = &receive_buffer[ 7 ];
#endif

    memset( &rn4870.device_buffer, 0, 255 );
    log_printf( &logger, " >>> app init done <<<  \r\n" );
}

void application_task ( void )
{
    rn4870_process(  );
#ifdef DEMO_APP_TRANSMITER
    rn4870_connect( &rn4870, &RN4870_ADDR_SLAVE[ 0 ] );
    Delay_ms( 100 );
    log_printf( &logger, ">>> sending data  <<<\r\n" );
    rn4870_send( &rn4870, RN4870_MTYPE_MSG, RN4870_DTYPE_STRING, RN4870_ID_MASTER, &message_payload[ 0 ] );
    Delay_ms( 100 );
    rn4870_disconnect( &rn4870 );
    Delay_ms( 100 );
#endif

#ifdef DEMO_APP_RECEIVER
    msg_flag = rn4870_read( &rn4870, &receive_buffer[ 0 ] );

    if ( msg_flag == 1 )
    {
        log_printf( &logger, ">>> data received <<<\r\n" );
        log_printf( &logger, ">>> data : " );
        log_printf( &logger, "%s\r\n", ptr );     
    }
#endif
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}


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

Additional Support

Resources

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