how to set a 3-wire SPI for si4735 control ?

Projects General Guidance
1

Settings in SPI library uses MISO & MOSI but i need to set it to SDIO (half-duplex), is there an option or another library ?
It is to control a si4735 FM Tuner !

Thank you !!!

2

Did you ever get this working? I'm considering the same thing - Arduino and the SI4735 or SI4737...

I've seen the Spark Fun breakout board with the SI4703 on it, but I want more functionality...

3

From the programming guide (Silicon Labs application note AN332) it looks like, depending on which command is used to read results, the radio sends responses either on SDIO (the same line) or GPO1 (making it a 4-wire interface).

MOSI -> SDIO
MISO <- GPO1
SCK -> SCLK
/SS -> /SEN

Send 0x48 followed by one byte of command and seven bytes of parameters on SDIO.
Send 0xA0 on SDIO to retrieve one byte of response on GPO1.
Send 0xE0 on SDIO to retrieve sixteen bytes of response on GPO1.

Looks like you have to do this to check to see if the radio is ready to take commands or return a response:

do {
    digitalWrite(SSPin,LOW);
    SPI.transfer(0xA0);   // Read status byte
    status = SPI.transfer(0);
    digitalWrite(SSPin, HIGH);
    } while (!(status & 0x80));  // Repeat until Clear To Send bit is set