NEWEST board is an Si4735 and Arduino pro mini( 3.2v 8 mHz) VERSION 2. This has both I2C and SPI interfaces. The board has been labeled better, with pro mini pin labels. Please refer to PU2CLR's GitHub for working software for this board. Si4735 radio and bandpass filter The radio is a copy of Ricardo Carratti's high effective Si4735 radio with an OLED. The Gerbers and BOM make it easy to fabricate this radio, although the Si4735 is difficult solder due to the pin spacing and the caps and resistors are 0603 size. The bandpass filter set is also a revised version of Ricardo Carratti's and SoftRock's filter set. All in a 1.25 x 2.75" circuit board. You can use all 4 sections to provide effective filters for the 80 through 10 meter bands. You can skip the lowest filter set and just use a jumper, to allow AM or FM, if desired. The band switching can be done with 2 spare pins on your processor. Cheers, Jim W0CHL (good on QRZ.com)