[hpsdr] Universal synth bus and stuff

[Phil Harman]

Hi Jonathan,

Re the bus signals.  What we have decided is that if we try and set all the 
bus signals in concrete now then we can be certain that some time in the 
future it will come back and  haunt us.

Some  pins are set - ground and the supply lines. For the signal lines we 
will either have an FPGA or a very low cost CPLD sitting on the bus on each 
card. That way we have a lot of flexibility into the future as to exactly 
what pin does what on the back plane. It also allows us to have two of the 
same card on the bus e.g. two Janus A/D D/A converters, without pin 
contention issues.

We have decided to allow for both I2C and SPI on the bus.  The reason for 
that is most of the chips we are currently using work on either and if we 
end up with a lot of  the same I2C chips then we may run out of address 
space.

73's Phil...




----- Original Message ----- 
From: "Naylor Jonathan" <naylorjs at yahoo.com>
To: <hpsdr at hpsdr.org>
Sent: Tuesday, May 30, 2006 3:09 PM
Subject: [hpsdr] Universal synth bus and stuff


> ***** High Performance Software Defined Radio Discussion List *****
>
> In the land if uwsdr we have been talking about the problem of
> different command sets and buses for the different DDSs and
> synthesizers that we are planning to use. At the moment all of the
> chips we are looking at are SPI, but I2C is common and we may need to
> handle that too.
>
> We are thinking that it may be better to define our own, very simple,
> serial bus to control the oscillators, and have a PIC on each RF board
> to convert that to the required commands for that chip. Therefore
> making all of the RF boards appear almost identical apart from the
> frequencies used.
>
> What does the HPSDR team think?
>
> Also we are looking to be compatible with HPSDR at the socket level so
> we can interchange hardware, but unless someone defines a pin standard
> soon, we will have to go our own way.
>
> Jonathan   ON/G4KLX
>
>
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