RadioStation click
PID: MIKROE-2822
Weight: 24 g
RadioStation click is a unique click board™ that can be used to broadcast the music via the FM
radio band. It features the Si4713-B30 from Silicon Labs, the best in class integrated FM
broadcast stereo transmitter, which operates in the frequency range of 76MHz to 108MHz. It can
also broadcast RDS/RDBS data. The click board™ can be equipped with a small FM antenna,
which is used to extend the broadcasting range.
One of the advantages of this versatile FM broadcast stereo transmitter IC is that it needs almost
no external components so it is very easy to work with it. That makes it an ideal solution for
using it in cellular phones, MP3 players, portable media players, wireless speakers, personal
computers and any other applications, where short-range radio broadcasting is wanted.
How does it work?
The RadioStation click broadcasts the audio signal by utilizing principles of the FM radio
broadcasting. The audio signal, brought to the low noise analog input terminals of the Si4713B30 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. This input is suited for line-level signals, up to 636mVpp.
The Si4713-B30 IC performs the frequency modulation in the digital domain, in order to achieve
high fidelity and optimal performance. The onboard DSP provides modulation adjustment and
audio dynamic range control of the signal, for the best listening experience. Audio signal is
processed to have the optimal dynamic qualities. Also, Si4713 has a programmable low audio
and high audio level indicators that allow enabling and disabling of the carrier signal, based on
the presence of an audio content.
The integrated DSP also takes care of the stereo MPX encoding and FM modulation of the
signal. The low level digital intermediate frequency (IF) signal is then filtered out and sent to the
output stage mixer, where it is converted to a radio frequency signal (RF). RF harmonics and
noise get filtered out additionally, to get a signal which is compliant with local regulations on RF
transmission (FCC, ETSI, ARIB…). The RF signal is broadcasted via the small antenna. The
device supports all kids of closed loop/pole FM antennas.
The click is designed for communication over the I2C/2-wire control interface. When selecting
2-wire mode, SCLK pin should stay at a HIGH logic level during the rising edge on the RST pin,
and stay HIGH until after the first start condition. Also, a start condition must not occur within
300nS before the rising edge on the RST pin. The 2-wire bus mode uses only the SCL and SDA
pins for communication.
The INT# pin of the Si4713-B30 is routed to the INT pin on the mikroBUS™ and it can be used
to provide an interrupt.
The SEN# pin of the Si4713-B30 is routed to the CS pin on the mikroBUS™ and it is used for
selecting the I2C address:
when SEN# is set to a HIGH logic level, the 7bit I2C address will be 1100011.
when SEN# is set to a LOW logic level, the 7bit I2C address will be 0010001.
The RST# pin of the of the Si4713-B30 is routed to the RST pin on the mikroBUS™. Setting it
to a LOW logic state will disable analog and digital circuitry, reset the registers to their default
settings, and disable the bus. Setting the RST pin to a HIGH logic level will bring the device out
of reset and place it in power down mode. A power down mode is available to reduce power
consumption when the part is idle. Putting the device in power down mode will disable analog
and digital circuitry and keep the bus active.
The Si4713-B30 IC has the capability of the received signal measurement. 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 signal, the antenna can't operate in
both modes simultaneously. This feature can be useful when calibrating the transmission power
of the click board.
Note: The Si4713-B30 integrates the complete transmit functions for standards-compliant
unlicensed FM broadcast stereo transmission. The user application must comply with the local
regulations on radio frequency (RF) transmission.
Specifications
Type
FM
Applications
Cellular phones, MP3 players, portable media players, wireless speakers, personal
computers and any other applications, where audio broadcasting on the small distance
is required.
On‐board
modules
Si4713‐B30 from Silicon Labs, the best in class integrated FM broadcast stereo
transmitter
Key Features
Easy to set, high quality integrated FM radio transmitter. It uses advanced audio
processing techniques to avoid over‐modulation and to achieve perfect levels of audio
for broadcasting.
Interface
I2C
Input Voltage 3.3V
Click board
size
M (42.9 x 25.4 mm)
Pinout diagram
This table shows how the pinout on RadioStation click corresponds to the pinout on the
mikroBUS™ socket (the latter shown in the two middle columns).
Notes
Pin
Pin
Notes
NC 1
AN
PWM 16
NC
Device reset
RST 2 RST
INT
15
INT
SEN 3
CS
RX
14
NC
NC 4 SCK
TX
13
NC
NC 5 MISO
SCL
12
SCL
I2C clock
NC 6 MOSI
SDA 11 SDA
I2C data
Power supply
3V3 7 3.3V
5V
Ground
GND 8 GND
GND
I2C address selection
GPO /Interrupt
10
NC
9 GND
Ground
RadioStation click electrical specifications
Description
Min Typ
Max
Unit
Ambient temperature
‐20
85
°C
Broadcasting frequency range
76
108
MHz
‐30
dBc
Transmit emissions in‐band (76–108 MHz)
SNR
53
dB
58
0.5
THD
%
Additional pins
Name
I/O
ANT
O
Description
ANTENNA output pin
Onboard settings and indicators
Label
Name
Default
Description
‐
Power LED indicator
PWR Power LED
Software support
We provide a library for the RadioStation click on our LibStock page, as well as a demo
application (example), developed using MikroElektronika compilers. The demo can run on all
the main MikroElektronika development boards.
Library Description
The RadioStation click board™ communicates with the controller by using the I2C/2-wire
interface. The library contains a wide set of functions for the complete control over the
RadioStation click. Some of the functions also return the status, so it is possible to take an action
in the case of error.
uint8_t RADIOSTATION_SetTuneFrequency(uint16_t freq)- Sets tune frequency
uint8_t RADIOSTATION_SetTunePower(uint8_t voltage, uint8_t capacitance)- Sets
tune power
uint8_t RADIOSTATION_GetTuneMeasure(uint16_t freq, uint8_t capacitance)- Reads
tuning measurements
Examples Description
Demo application shows how to configure RadioStation click to receive the signal from the
audio connector and broadcast it on 100.00 MHz frequency.
The application is composed of three sections:
System initialization ‐ Initializes GPIO pins, I2C peripheral used for communication between
RadioStation click and MCU, and UART used for logging. This function also initializes driver.
Application initialization ‐ (Code snippet) Powers on RadioStation click and setups frequency for
signal emission and writes a message to UART when emission is started.
Application task ‐ Sequentially reads measurements of the signal quality.
void applicationInit()
{
status_ = RADIOSTATION_PowerUp();
RADIOSTATION_GetRevision(&buff[0]);
status_ = RADIOSTATION_SetTuneFrequency(transmitFrequency);
RADIOSTATION_BusyWaitForSTCINT();
RADIOSTATION_GetTuneStatus(1, &buff[0]);
status_ = RADIOSTATION_SetTunePower(115, 0);
RADIOSTATION_BusyWaitForSTCINT();
RADIOSTATION_GetTuneStatus(1, &buff[0]);
UART1_Write_Text("Radio Click now broadcastig at selected frequency");
}
The full application code and ready to use projects can be found on our LibStock page.
Other mikroE Libraries used in the example:
UART
Additional notes and information
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.
https://www.mikroe.com/radiostation‐click 12‐20‐17