So, before I splash out on the EDK, I'd really appreciate some advice on what the real MHz limits are on the microblaze (almost certainly in a Spartan-3E). From the webpage it says it'll do 100MHz but then qualifies it as execution from BRAM only. Questions...
- Does the 100 MHz figure imply a 100 MHz bus-speed too ? I see a bunch of tutorials where the bus is only 66MHz.
- How does the system scale as you add more PLB peripherals, or OPB ones for that matter
- If I make a peripheral, do I get bus-mastering built-in (or at least supported) with the tools provided ? It would be useful for more than one peripheral to access the SDRAM controller, for example :-)
- If I can persuade myself to splash the cash on a V4FX design instead, what sort of real-world MHz am I looking at for the PPC chip ? Again, it claims 450MHz in the datasheets, but is that realistic ?
Since this is only a hobby, $500 is a large chunk of pocket-change so I'd be very grateful for answers to the above. If (as I've been told) it's typically "difficult" to get 100MHz from a microblaze (with h/w multiplier, barrel shifter, SDRAM interface, and a couple of peripherals), I may look at using the FPGA to interface with an external coldfire at 147MHz instead, and then I might not need the EDK, though unit costs of the board will be more expensive...
Thanks in advance,