10 min

Broadcast the music via the FM radio band using the Si4713-B30 and STM32L162ZE

Superior performance in FM broadcasting covering a frequency range from 76MHz to 108MHz

RadioStation Click with UNI Clicker

Published Aug 29, 2023

Click board™

RadioStation Click

Development board

UNI Clicker


NECTO Studio



Combined with the capability to broadcast both music and informational data, this project is a match for anyone looking to explore the world of FM broadcasting or to develop applications requiring FM signal transmission



Hardware Overview

How does it work?

RadioStation Click is based on the Si4713-B30, an FM radio transmitter with receive power scan from Silicon Labs. The RadioStation Click broadcasts the audio signal by utilizing the principles of FM radio broadcasting. The audio signal, brought to the low noise analog input terminals of the Si4713-B30 routed to a mini 3.5 female jack on board, is attenuated and converted into an alias-free, digital format. The digitalized audio is then sent to the digital signal processor (DSP) section of the Si4713-B30 IC, which provides modulation adjustment and audio dynamic range control of the signal for the best listening experience. The audio signal is processed to have the optimal dynamic qualities. Also, Si4713 has programmable low audio and high audio-level indicators that enable and

disable the carrier signal based on the presence of audio content. The Si4713-B30 IC can be used to measure the received signal. The antenna which is used to broadcast the signal can also be used to accept the incoming signal sent by the receiving device. Although it can be used both to receive and transmit signals, the antenna can't operate in both modes simultaneously. This feature can be useful when calibrating the transmission power of the Click board™. The Si4713-B30 integrates the complete transmit functions for standards-compliant unlicensed FM broadcast stereo transmission. The user application must comply with the local radio frequency (RF) transmission regulations. RadioStation Click uses a standard 2-Wire I2C interface to communicate with the host

MCU, supporting clock frequency of up to 400KHz. The I2C address can be selected over the SEN pin of the mikroBUS™ socket, depending on the logic state. The radio transmitter can be reset over the RST pin, which will, among others, disable analog and digital circuitry. The device will interrupt the host MCU over the INT pin if a condition occurs, such as the frequency exceeding the deviation level. This Click board™ can be operated only 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.

RadioStation Click hardware overview image

Features overview

Development board

UNI Clicker is a compact development board designed as a complete solution that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It supports a wide range of microcontrollers, such as different ARM, PIC32, dsPIC, PIC, and AVR from various vendors like Microchip, ST, NXP, and TI (regardless of their number of pins), four mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a debugger/programmer connector, and two 26-pin headers for interfacing with external electronics. Thanks to innovative manufacturing technology, it allows you to build

gadgets with unique functionalities and features quickly. Each part of the UNI Clicker development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the UNI Clicker programming method, using a third-party programmer or CODEGRIP/mikroProg connected to onboard JTAG/SWD header, the UNI Clicker board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Type-C (USB-C) connector, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or using a Li-Po/Li

Ion battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board (plus USB HOST/DEVICE), including the well-established mikroBUS™ socket, a standardized socket for the MCU card (SiBRAIN standard), and several user-configurable buttons and LED indicators. UNI Clicker is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

UNI clicker double image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M3

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

I2C Address Selection
Power Supply
I2C Clock
I2C Data

Take a closer look


RadioStation Click Schematic schematic

Step by step

Project assembly

UNI Clicker front image hardware assembly

Start by selecting your development board and Click board™. Begin with the UNI Clicker as your development board.

UNI Clicker front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for STM32F745VG front image hardware assembly
Prog-cut hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
UNI Clicker Access 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
Necto image step 7 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

After loading the code example, pressing the "DEBUG" button builds and programs it on the selected setup.

Application Output Step 1

After programming is completed, a header with buttons for various actions available in the IDE appears. By clicking the green "PLAY "button, we start reading the results achieved with Click board™.

Application Output Step 3

Upon completion of programming, the Application Output tab is automatically opened, where the achieved result can be read. In case of an inability to perform the Debug function, check if a proper connection between the MCU used by the setup and the CODEGRIP programmer has been established. A detailed explanation of the CODEGRIP-board connection can be found in the CODEGRIP User Manual. Please find it in the RESOURCES section.

Application Output Step 4

Software Support

Library Description

This library contains API for RadioStation Click driver.

Key functions:

  • radiostation_get_asq_status - This function returns status information about the audio signal quality and current FM transmit frequency

  • radiostation_power_up - This function powers up the chip with default settings

  • radiostation_get_tune_status - This function returns status information which is set by radiostation_get_tune_measure, radiostation_set_tune_frequency or radiostation_set_tune_power

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * \file 
 * \brief RadioStation Click example
 * # Description
 * RadioStation click can be used to broadcast the music via the FM radio band 
 * ( which operates in the frequency range of 76MHz to 108MHz ).
 * The demo application is composed of two sections :
 * ## Application Init 
 * Initialization driver enable's - I2C and sets transmit_frequency.
 * ## Application Task  
 * In this example Radio Station Click is receiving signal from audio connector and broadcasting 
 * it on 100.00 MHz frequency.
 * \author MikroE Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "radiostation.h"

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

static radiostation_t radiostation;
static radiostation_cmd_t radiostation_cmd;
static log_t logger;

static uint8_t buff[ 16 ];
// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
    log_cfg_t log_cfg;
    radiostation_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.

    radiostation_cfg_setup( &cfg, true );
    radiostation_init( &radiostation, &cfg );

    radiostation.transmit_frequency = 10000; 
    radiostation.status = 0xFF;

    radiostation_default_cfg( &radiostation, &radiostation_cmd );

void application_task ( void )
    radiostation_get_asq_status( &radiostation, &radiostation_cmd, &buff[ 0 ] );
    Delay_ms( 50 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

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

Additional Support