@Mark, Out of curiosity, why would you go for something like Microblaze
instead of a hard arm core? As far as I'm aware, Microblaze and Nios are still
licenced, and considerably slower than the hard arm cores. Both Altera and
Xilinx are pushing those, and cheap(ish) development boards are starting to
appear as well - I'm now playing with the Altera version, the Arrow/Terasic
sockit board, and Terasic is coming with a cheaper and imo nicer version of
that as well.
For Al's question, I'm thinking such a development board could maybe be useful
- arm & fpga in one chip, with interfacing in between already taken care of,
lots of memory on the board and in the chip itself. No need to do board design
or BGA soldering, depending on the board, maybe only level converters would
need to be added.
And, even though most of the interfacing between arm and fpga is somewhat
complex, there are also 'simple' variant - at least Altera's variant has 32
GPIO input and output pins in its arm core that are connected to the fpga.
On Sunday, December 29, 2013 10:26:58 Mark J. Blair wrote:
On Dec 29, 2013, at 07:38 , Al Kossow <aek at
bitsavers.org> 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.
I don't know whether you have particularly strong preferences for or against
various FPGA vendors. At work, we use Xilinx stuff heavily, including both
bottom-end parts in the sub-$30 range and top-end just-released
OMFG-that's-expensive stuff. I tend to be biased towards Xilinx FPGAs since
they're what I have the most experience with.
I have a number of projects on my mind's back burner (i.e., the projects I
think about all of the time but never seem to begin in earnest) involving
FPGAs and vintage hardware. Lately I've been thinking in terms of using
Spartan 6 family FPGAs, since the smaller ones are pretty cheap and I have
recent experience using them in my day job. I've also thought a lot about
what microcontrollers I might want to mate up with FPGAs (STM32F, MSP430,
board-level things like Rasberry Pi or Beaglebone Black), but most recently
I've started to gravitate towards embedding a synthesized processor into
the FPGA rather than wiring up an external one.
First I thought about using an open source 8051 core that I read about, but
at the moment I'm thinking of Xilinx's Microblaze core family instead. I
did a quick experiment and found that it took up around 25% of the smallest
Spartan 6 in the configuration I tried. Larger Microblaze configurations in
other Xilinx families can even run Linux.