10 Nov
2013
10 Nov
'13
4:45 a.m.
On 11/3/13 8:26 PM, Mark J. Blair wrote:
On Nov 3, 2013, at 15:39 , Robert Jarratt
<robert.jarratt at ntlworld.com> wrote:
I'm on the same path. The "Mojo fpga" board is very cool and cheap.
I'm about to crank it into a few interface boards to see how it works.
The question for is whether or not the AVR <-> FPGA SPI interface is
fast enough to do disk & tape transfers over USB. I think the
limitation is the AVR's clock speed. It might be simplest to just put
a 4 wire MMC port off the FPGA and put a simple cpu inside the fpga to
do basic i/o work. Any simple core should do the job.
-brad
BeagleBone is certainly looking like a good
candidate. If I need to
supplement with a FPGA, what is the smallest/cheapest development board
option? DE0-Nano seems to be the cheapest I have found so far.
I haven't
looked into off the shelf dev boards much since I expected to make my own PCB anyway. My
first impulse is to try a Xilinx Spartan 6, out of force of habit. The largest one
available in a TQFP package costs around $15 at Digi-Key and has 64kx9 of dual-ported RAM
blocks if I recall correctly. I haven't thought things out far enough to determine if
the gate count is large enough.