Re: Si4734 Hardware and Software Guides

Roy <roy.dyball@...>

Hi Scott

Thank you for the link to the sample C code and the explanation. All my code is written in VB.NET 2008. I have many years experience with it from my previous business dealings before I retired and the program was going before I thought too much about it. I have got the 3 wire interface running really well and the 9 bit data word was a real challenge especially in VB.NET, I think the hardest part was getting the half clock cycle delay correct during the bus turn around.

Because the Tecsun uses the 3 wire interface I feel it is best to stick with it while they use it because I can unhook my interface, and as soon as I switch the local MCU control lines back in it takes over without a fuss and you can still use any changes you have made until power down while using the radio normally.

I am really leaning toward using an MCU like you are doing and am looking forward to seeing your final results. I noticed you have posted more pictures and your radio with interface looks good now it is back together.

Cheers Roy.

--- In ultralightdx@..., "sdwillingham" wrote:
> Roy,
> The 9-bit control word is a bit of a pain, but although it is not
> obvious, it is not too hard to use a standard 8-bit SPI-type
> interface to communicate with the Si4734. The technique is used
> in this software:
> (See the CONTROL_WRITE and CONTROL_READ macros in file
> F320_Si470x_Interface.h. Note, this code is for the Si470x parts,
> but works the same for Si473x if you change the chip-address to
> 0xA0 instead of 0x60.)
> The basic idea is to do a 2-byte read or write by packaging the
> 25-bit command+response or command+data in four 8-bit transactions.
> (While manually banging the SENB signal before and after the
> 32-bits.) The first 25 bits are as documented for the part. The
> last 7 bits just hang on as partial extra response or data. When
> SENB is driven high, the last partial transaction is aborted and
> the control interface state-machine is reset for a new transaction.
> Perhaps you can simplify your interface with this technique.
> Cheers,
> Scott
> --- In ultralightdx@..., "Roy" roy.dyball@ wrote:
> > The 3 wire (SDIO SCLK SEN) control interface opened up a big can of
> > worms because it uses a non standard nine bit control word. I then
> > discovered I could use the advanced bit banging functions of the FTDI
> > chip to construct a non standard nine bit word and get my I/O routines
> > running fast enough to produce good results. By this time it was clear
> > to me that RS-232 would not do the job.

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