[Fpga-synth] XSOC ?

[Veronica Merryfield]

Hey Scott

There is a list called fpgacpu that is mentioned on Jan's site. I am a 
moderator on that group.

The XSOC project is a risc like cpu that is fully synthesizable as you have 
found. Jan did an amount of work pre picoblaze and Nios to show that a cpu 
within a SOC on an fpga was a practical reality using free tools. You will 
need to build the compiler as well which is based on lcc and uses Jan's 
backend. Jan also provides a simulator and assembler.

If you want the experience of doing this or you want to add custom 
instructions to the instruction set, then go get xsoc and build it in. If 
you just want some cpu  power to add to your design, thn go with the built 
in CPU. Both Xilinx and Altera have good tool support, although it will 
require a bit of 'faffing' around and they have some IP for peripherials.

For what it's worth, I have made a risc like CPU with a bunch of custom 
instructions and managed to build an interupt and dma structure in by jam 
loading custom instructions into the pipeline at the load stage (the DMA was 
a single instruction that was inserted in the pipeline to make a move and 
the interrupt would jam load a single instruction to save state and jump to 
a vector from a lookup). It was fun as a project but the only other reason I 
might do it is for a security conscience application (unknown instruction 
set when looking at the binary).

In my day job, I use a PPC in a Xilinx running Linu - much easiey than doing 
our own CPU.

I think having a CPU and tools in place is a lot lot easier than doing your 
own CPU.

Veronica

----- Original Message ----- 
From: Scott Gravenhorst
To: fpga-synth at rubidium.dyndns.org
Sent: Saturday, November 17, 2007 9:13 AM
Subject: [Fpga-synth] XSOC ?


http://www.fpgacpu.org/xsoc/

Does anyone have any experience or inside info on this?

There is a "beta" zip file on the site.  It's a 16 bit RISC processor
written in synthesizable Verilog for an FPGA.  I'm wondering if this might
be useful in writing a MIDI controller capable of controlling a 16 voice
polysynth.  I know I could probably do it with PicoBlaze, but I think a 16
bit MCU would make that a bit easier.

-- 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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