[Fpga-synth] Altera Cyclone II Starter Board ?

[Mike Ravkine]

Scott,

First, go look at an Altera DE2 board 
(http://www.altera.com/education/univ/materials/boards/unv-de2-board.html).

Judging by the looks of it and the feature list, this board is the DE2's 
little brother. They are both made by the same company in taiwan, 
Terasic (http://www.terasic.com.tw). The primary differences appear a 
lack of protective cover, character LCD, TV decoder and a smaller FPGA.  
However, I paid $300 for my DE2, supposedly marked down from $599 
(terasic site lists them for $495).  This board is a STEAL at $150.

Plus, this addon ( 
http://www.terasic.com.tw/cgi-bin/page/archive.pl?Language=English&CategoryNo=39&No=78 
) is almost irresistible, and it works with the DE2 as well .. I think I 
may have to get one to replace the character LCD in my synth ;)

As far as that audio codec goes, I have had good luck using the DAC 
portion at 48khz 16-bit. You need a 18.432Mhz clock (x384), easily made 
from 27mhz. This board has 24, 27 and 50 Mhz available, which is even 
better then the DE2's 27 and 50.  I haven't tried the ADC at all.  
Supposedly DAC can go up to 96khz, but I haven't tried that either.

The boards share a PS2 port for mouse or keyboard input (I use a PS2 
keyboard as my primary input).  There is also VGA output (4-bit on this 
board vs 10-bit on the DE2) as well as an SD interface for memory cards 
(very handy capability, especially for a synth) and the usual assortment 
of bunch and switches.

The Altera tools come with a free softcore called NIOS2. To create a 
system, you use a GUI system builder where you can mix your own 
components (for instance, I built my synth control bus interface as a 
NIOS2 component) with pre-defined components and drivers (all of the 
memory-based devices on the board will be supported out of the box 
including memory and flash, as will all of the input and output devices) 
and it will automatically wire them up and place them in the address 
space.  I am told Xilinx has something similar?

To write your code in C/C++ you get an Eclipse-based IDEA with a full 
gcc-based toolchain.  The only downside is that the free version only 
works when there's a host PC attached.

--Mike

Scott Gravenhorst wrote:
> http://www.altera.com/products/devkits/altera/kit-cyc2-2C20N.html
>
> Has anyone messed with this?
>
> All of the following is my opinion based on published _marketing_ information.
>
> I like the audio connectors and the inclusion of both SDRAM (8 Mbyte) and
> SRAM (64 Kbyte), but I have no idea how nasty the pin sharing is.  I'd also
> have preferred at least twice that amount of SRAM.  It looks like the FPGA
> internal RAM is smaller than the Xilinx XC3S500E, but it has 26 18x18
> dedicated multipliers vs. XC3S500E which has 20 (with shared routes to
> block RAM).  Even though the "equivalent gate" bogus count is about twice
> the Xilinx part, it appears to me that the Xilinx part has about the same
> capacity.
>
> The Cyc-II multiplier arrangement is interesting, but I've not yet needed a
> 9x9 multiplier - however, I'm also not a 10 year design veteran either. 
> The one time I needed a small multiplier it was to multiply a varying value
> by a constant and it was easy to build that out of a few adders.
>
> Also, what do they mean by 24 bit resolution coder-decoder ?  It doesn't
> say _DAC_ per se and "24 bit resolution" looks suspicious of something
> other than a real 24 bit DAC to me.
>
> It _looks_ like the board price is $150, so it's comparable to the S-3Esk,
> unless there's extra stuff you have to buy to make it work as an audio
> development board.  It also appears as if the dev software comes included
> with the board.
>
> -- ScottG
>
> -------------------------------------------------------------
>
> -- Scott Gravenhorst
> -- GateMan II - Xilinx Spartan-3E Based MIDI Synthesizer with SVF
> -- PolyDaWG/8 - 8 Voice FPGA Polyphonic MIDI Synthesizer
> -- FatMan: home1.gte.net/res0658s/fatman/
> -- NonFatMan: home1.gte.net/res0658s/electronics/
> -- When the going gets tough, the tough use the command line.
>
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