On 29.12.2013 16:38, Al Kossow wrote:
WHAT to use for the microprocessor and FPGA has been
the stumbling block for the
10 or so years of false
starts that I've had with microcontroller/FPGA projects. There never seems to be
the right way to glue the
two together.
The last thing I actually did in a commercial/industrial environment
(i.e. in my
last job) was some sort of ARM processor with FPGA attached via SRAM interface
and a glue CPLD. The CPLD's main function was to provide a bitstream loader
device that could then used by the microprocessor. The whole thing runs
extremely reliably.
Today I would not hesitate to use the TI processor that's used on the Beglebone
board. You can even use a beaglebone board on top of a selfmade FPGA board.
The only thing to achieve (probably already done) is setting up the memory
controller to use the external bus/memory interface to the attached FPGA.
Another approach: Use a soft processor like Microblaze (Xilinx) or the
equivalent Altera thing.
I have used Microblaze in several setups.
Currently I'd like to give Xilinx Zynq 7000 a try. Powerful ARM + FPGA in one
package.
Current thought
is just connect the two boards with SPI and not try to tie the two boards
together as intimately.
Probably easy to implement. But then you would have quite
low bandwidth between
your host computer and the vintage system. Even worse when ethernet is tied to
the microcontroller.
hen I looked
at how f'ing complicated
PCI-e is. So then, since like a fool I bought a couple of the Intel boards, I
looked at PCI-e - PCI bridges
at which point I said this is all getting WAY too complicated.
I think it's
really worth learning PCI-E. I wish to find some time to play with
PCI-E on FPGA.
So I'm back to a couple of bus translator PCBs
with the actual microcontroller
and FPGA on separate mezanine
cards so whatever the silicon is that the bus translators stay the same.
That's
quite a good idea: The bus driver stuff can even be homebrew. And needs
large boards. Having the high tech part on an extra board is fine.
I'm currently finishing the design of the DECtape
G888 replacements to get those
sent off for fab.
Oh, I'd be interested in several of them!
:-)