- FM radio Si4703 page-
PIC printed circuit board, the board size is 88 x 110mm, through plated and RoHS compliant (lead free solder used in manufacture).
The remaining components needed to complete the board are listed below and are easily obtainable from CPC, Farnell, Rapid Electronics, RS, etc. I tend to use Farnell or CPC but it is worth shopping around for the best price as prices do varying considerably - particularly the LED display. Also minimum order value and postage needs to be taken into consideration.

Components marked 'supplied' come with the circuit board.

The alpha-numeric display isn't essential and the board will work without them installed. If they are fitted then the frequency of the radio station will be displayed. The MSF Decoder page has more constructional details.

As well as the printed circuit board you also get the 4 PNP transistors (BC327-25), USB pcb connector, 3.3V voltage regulator and single pole on-off switch.

The SparkFun FM board plugs into J1 connector (marked FM - left hand side) on my printed circuit board.The board used for this project was also used for the MSF project featured in RadioUser November 2014.


If you are interested in this project and want the printed circuit board please send an e-mail to the following address and put 'FM radio' in the subject line. The printed circuit board costs 12 (includes VAT and postage to UK), I will e-mail you with information on ways to pay. Included with the circuit board are components that are more difficult to source or where the circuit board is designed for a specific component (e.g. on/off switch).




Controlling the SparkFun FM Tuner Evaluation Board - Si4703


Featured in RadioUser magazine November 2015.


PIC board display test - hex file (2 Kbytes zipped)




When running the PC software click on the USB connect button and this should list all the active COM ports - click to select the appropriate COM port for the PIC Decoder board. 

If you are running Windows 10 then the USB Serial Communications driver is already installed.

The next PIC program tests the tactile buttons - the display should show all '1's and when a button is pressed the appropriate LED should change to '0'.



To program the PIC microcontroller use MPLAB IPE (comes with MPLB X).

Do not power this board from the PICkit3 programmer as the LED display requires +5V and if you set the PICkit to output 5V then the PIC microcontroller will be damaged as it only needs 3.3V. 

If you are using a PICkit 3 then it plugs directly into J2 (marked PICkit), use a 90 degree pcb header.

If you have installed the alpha numeric LED display then the following hex program tests the multiplexer and display. Program the PIC and if everything is working then various segment patterns should be visible, then a sequence of letters/numbers as the program steps through the ASCII character set.

To download the file right click the link and select 'save target as'....

If the board is working then download the FM hex code. This version does not use the USB or display, included in the zip file is the mikroPascal source code.

PIC FM board hex and source file (4 Kbytes zipped)



The next hex file uses the USB so that the FM radio can be controlled by the PC, the board buttons control the volume and next station scan. 

PIC FM board hex - scan and controlled via USB file (22 Kbytes zipped)



After the PIC is programmed and the board plugged into the USB Windows 10 will automatically install the USB driver. Check 'Settings', 'Devices', 'Connected Devices' and you should see USB Serial Device listed.


If you are not running Windows 10 and your PC displays the USB device and a pop-up message says 'Device driver software was not successfully installed' then right click on the icon and select properties, then select 'Hardware' from the pop-up menu. Then click the Properties button, then 'Change settings'. Press 'Update Driver' and then select 'Browse my computer for driver software' option and set the search to the folder where the hex code is located. When done the icon should change and read FM radio Virtual Com Port.

Windows PIC board controlled via USB file (168 Kbytes zipped)




PIC tactile switch button test hex code (1 kbytes zipped)