Re: gEDA-user: mcu to sdram interface project

[Eric Brombaugh <ebrombaugh1@xxxxxxx>]

DJ Delorie wrote:
>> For FPGA configuration I used slave serial mode and drove the DIN/CCLK 
>> direct from a SPI port on my MCU - saved having to use Xilinx's special 
>> configuration flash parts. Does mean that the start-up process is a bit 
>> more complex though.
> 
> I thought of doing that, but the advantage of using a separate eeprom
> is that I can use the mcu to download the bitstream to it faster than
> I can reprogram the MCU to have a built-in bitstream.  Plus I can
> learn something new in the process ;-)

It was the reverse for me - I've always used the Xilinx config flash 
parts in the past and I wanted to see how well the other approach would 
work. Turns out to be pretty easy, although there are a few minor 
caveats about the configuration process that I learned along the way.

> I also thought about adding a serial port, ethernet chip, and sdcard
> slot to the test board, but then I decided "one step at a time".  If I
> were using a 32 bit mcu I'd reconsider - big RAM is a key to uclinux
> support.  The m32c is only a 16 bit MCU.  Maybe I'll add them anyway,
> though, just for fun.

I'd definitely recommend putting an SD slot on. The hardware is cheap, 
the interface is simple and there's so much you can do with it. I store 
my FPGA bitstream on the SD card, so updating the the hardware design is 
  just a matter of copying the file onto the card and clicking it into 
the board.

Eric


_______________________________________________
geda-user mailing list
geda-user@xxxxxxxxxxxxxx
http://www.seul.org/cgi-bin/mailman/listinfo/geda-user