I am very unfamiliar with FPGA cores. So bear with my ignornance a bit.
I've seen many people refer to cores as if they were very common, but how does someone use a CORE made by someone else?
I have seen a 8051 VHDL core floating around but how does someone use it, what is it good for? Does Xilinx Foundation support the use of cores? if so how?
It depends on the type of core. A soft-core is delivered as a piece of HDL that you can synthesize along with your own HDL.
A hard-core is delivered as an (possibly even encrypted) netlist of gates (often EDIF-format) that you can still compile in your fitting tool. But if you look at the EDIF you won't find any meaningful netlist names so reverse engineering it would not be worthwile the effort.
Some tools encrypt the EDIF and have decryption keys built into the fitting tool so the user cannot see anything. The only thing you could look at is the post-place-and-route netlist. So there's not much to see, and making modifications is totally out of the question.
Think about DDC (digital down converter) core, I am workin on it for about 6 months and still nothing. The DDC is composed by multipliers, CIC FIR filters and SM to control all.
You can crate your own code (5 months) then you use simulator (1 month) and finaly you or your boss figure it out that this is not worth of your time.
okay I have a VHDL 8051 core, how do I do something with it? How do I use inputs and outputs? How do I download my ASM compiled HEX code into it? What is the method from 1. obtaining core to 2. actually making use of it?
hi:
1.If you have VHDL core (8051) then use Xilinx FPGA to implement
you core. So you have real 8051 device.
implement way :
a. use Xilinx ISE5.1 to synthesis VHDL core , place and route, to get
VHDL netlist
b. post simulation VHDL netlist , if timing ok, then you get real 8051
2. design 8051 , EEPROM circuits, and you can put binary format
assembly in EEPROM , then you have small 8051 ststem