[hpsdr] [OZY] Initial OZY Schematic Posted For Review and Comments - May 10, 2006

[Philip Covington]

Hi Bill,

On 5/11/06, Bill Tracey <bill at ewjt.com> wrote:
<snip>
> One thing Phil H has done debugging the Xylo is to have an RS 232 out that
> he can write to from within the FPGA for debugging.  I'd planned to add one
> of the FTDI serial -> USB chips to my Xylo to be able to do this via a USB
> port.  Any interest in doing this on the Ozy's FPGA?

I assume that you are talking about adding RS-232 output from the FPGA
instead of using the RS-232 output of the FX2?  The SN75C1406 that I
am going to use for the FX2's RS-232 has an extra unused RX/TX pair
that I could hook up to a pair of pins on the FPGA for RS-232
capability.  The question is which pins? (which is even more
complicated by adding support for SRAM below).

> Given the uncertainty in how much FIFO space we will need to maintain
> glitch free audio, I'm a bit nervous on how scarce the RAM bits may
> become.  so keeping some capability for an external RAM at this point seems
> to be a good idea.   If we never populate it great, the 32 pins can be used
> for other things.

Anyone have suggestions on a 128Kx8 SRAM?  I was looking at using the
ISSI 63LV1024  12 ns which Mouser carries.  Unfortunately the only
package that they stock is the SOJ type so I'd probably put an
optional socket on the OZY for it (if there is room).  Cypress has
some SRAM in the 1Mb size but it looks like it is pretty scarce.

> Regards,
>
> Bill
>

I am already scarce on I/O pins if we add the SRAM with the EP2C5
QFP208 part... I guess I could bump up to the EP2C5 256 BGA part which
would give us more I/O.  Who wants to deal with BGA's ?  No hand
soldering there... maybe hot plate or toaster oven with paste...

73 de Phil N8VB

 1147356275.0