[hpsdr] Operating Configurations

[Lyle Johnson]

Hello Phil!

> 1. It would be nice if the EEPROM parts from Dallas were easier to
> get.  There aren't too many 1-Wire devices that are easy to get in
> general though.

If we decide to do this and decide on, for example, the DS2431P, then 
I'll just order a couple hundred of them and we'll have them available.

They are currently 7 weeks lead time, but I suspect that by the time we 
have Janus and Ozy ready to go, 7 weeks will be upon us.

> If we use the 1-Wire devices with some EEPROM, why could we not just
> encode a board ID and revision number?  The FX2 goes out and reads
> these IDs from the plugged in boards and returns the results to the
> host computer.  The host computer looks up the board IDs in a table
> and does the appropriate thing.  In case of duplicates it
> differentiates the boards by the unique serial number.

Yes.

> Any which way I like the idea of having the 1-Wire bus available.
> 
> 2. Putting an I2C EEPROM on each board places a limit on the number of
> boards because of the previous mentioned 3 configurable address lines.
> Are there any serial EEPROMs that support the 10 bit extended
> addressing?  I would rather not deal with sub-buses or bus switches
> for getting around having multiple devices with the same address on
> I2C.
> 
> 3. SPI EEPROMS would not be practical since they each need a CS line
> and we only have 5 defined on the bus.
> 
> If there is a EPM240 (or FPGA) on the slave boards that is standing
> between the board and the ATLAS bus (like the one in JANUS), we might
> be able to do a little trickery with the SPI bus by defining some
> simple addressing protocol that the EPM240 decodes.  That way we could
> have multiple SPI devices on a board but still use the ATLAS nCS(0:4)
> chip select lines from the OZY.  By writing to a register in the
> EPM240 we would select which SPI device on the board that is being
> addressed/connected to the ATLAS SPI bus.  One particular address
> would be reserved  for reading/writing the EPM240 user flash memory
> with the board's configuration settings/ID.  Since we know that
> address and we know which nCS we are asserting, then the FX2 could
> read the board configs on start up as in the 1-Wire case above.

If it is an FPGA, though, that needs to be configured by Ozy first, 
we're back to square one :-(

73,

Lyle KK7P


 1147465584.0