Adafruit Si4713 User Manual
Adafruit Si4713 FM Radio Transmitter with RDS/RDBS
Support
Created by lady ada
Last updated on 2020-10-27 10:20:26 PM EDT
Overview
Yaaar! Become your very own pirate radio station with this FM radio transmitter. This breakout board, based on the
best-of-class Si4713, is an all-in-one stereo audio FM transmitter that can also transmit RDS/RBDS data!
Wire up to your favorite microcontroller (we suggest an Arduino) to the I2C data lines to set the transmit frequency and
play line-level audio into the stereo headphone jack. Boom! Now you are the media. Listen using any FM receiver such
as your car or pocket radio receiver - this is an easy way to transmit audio up to about 10 meters / 30 feet away.
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 3 of 27
This transmitter even has RDS/RBDS support - that's text/data transmissions that many modern FM receivers support.
(It's how some car radios can display the FM station and current song playing). You can transmit just about any text you
want, set the station identifier as well as the 'freeform' buffer.
Best of all, you'll be up and running in minutes with our awesome Arduino library, example code and tutorial!
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 4 of 27
Pinouts
There's a couple pins on this here breakout, lets cover them all in groupings by 'type'
Audio Inputs
LIN - this is the line level LEFT input. Its connected to the headphone jack as well but in case you want to wire
directly without a chunky cable, pipe line level (~0.7 Vpp) audio into here. There's an AC blocking capacitor on
board so it can be DC biased
RIN - same as LIN but the RIGHT input.
Power Pins
Vin - this is the power input pin. You can power the chip from 3-5VDC. Ideally you should use the same voltage
you use for logic levels. For an Arduino, that's usually 5V
GND - this is power and logic ground, connect to your microcontroller's ground pin
3Vo - this is the output from the onboard regulator, 3.3V nominal. You can use this if you need up to 100mA of 3V
regulated voltage
Interface Pins
The FM transmitter chip requires a microcontroller for setting it up unlike pure-analog solutions that have a tuning
potentiometer. The trade off is some code is needed, but the output is digitally tuned so its much more precise.
Our codebase uses I2C to communicate. The chip supports SPI as well but it was annoying enough to support just I2C
so we don't have code examples for SPI!
All the interface input pins are 5V friendly, and can be used with 3-5V logic
RST - This is the Reset pin. You must have this pin toggle before starting to communicate with the chip. When at
logic 0, the chip is in reset.
CS - This is the Chip select pin, used in SPI mode. It also determines the I2C address. When pulled high (it is by
default) the I2C address is 0x63. If this pin is shorted to ground, the I2C address is 0x11
SCL - this is the I2C clock pin, connect to SCL on your microcontroller.
SDA - this is the I2C data pin, connect to SDA on your microcontroller.
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 5 of 27
Extra GPIO Pins
There's also two "GPIO" pins, you can use these to blink LEDs. The initial state of these pin sets up the chip for Analog
Mode so don't short them to ground or VCC during reset. They are 3V output only!
GP1 - this is GPIO #1
GP2 - this is GPIO #2
GPIO #3 is used for the 32Khz clock generator onboard.
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 6 of 27
Assembly
Prepare the header strip:
Cut the strip to length if necessary. It will be easier to
solder if you insert it into a breadboard - long pins down
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 7 of 27
Add the breakout board:
Place the breakout board over the pins so that the short
pins poke through the breakout pads
And Solder!
Be sure to solder all pins for reliable electrical contact.
(For tips on soldering, be sure to check out our Guide to
Excellent Soldering
(https://adafru.it/aTk)
).
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 8 of 27
You're done! Check your solder joints visually and
continue onto the antenna
An antenna is required! We provide a 1meter long wire
but you can also use a shorter or longer piece as
desired.
Strip a few mm from the end
© Adafruit Industries
https://learn.adafruit.com/adafruit-si4713-fm-radio-transmitter-with-rds-
rdbs-support
Page 9 of 27
Loading...