The BK1085 is a PLL FM transmitter with 64-125 MHz band, in this example i use an Arduino NANO
and my new BK1085-DEV board.

Even thoug has been used the Nano board, the sourcecode has been compiled with Eclipse and AVR GCC, not Arduino official

IDE and the code is pure C, for the upload i use a USBASP programmer, that wipes out the Arduino bootloader.

The example code simply switches between some stations and pushes a PWM signal inside the R and L inputs
to send noise for a little time on each station, you could connect an audio source.

The project started with a FM car modulator for MP3 music, then i decided to build my development board, you
can see the "history" of my work in the pictures below.

Arduino connections:

D2 MOSI
D3 SCK
D9 L-CH/R-CH NOISE (+ 470ohm to gnd)
5V 3V3 (power all the system with 3v3)
GND GND

Download gerber

Download sourcecode

Download BK1085 datasheet

The MCU has been removed, it provided the clock source so i used a crystal and 2 capacitors for the oscillator.

395

Then i designed my small DEV board....

bk1085 scheme

 

473

 

472

 

bk1085 00

 

bk1085 01