View Full Version : FPGA's

05-23-2005, 11:52 AM
Hey People,

Has anyone used a FPGA ? The last time i used one was a Xilinx Spartan II, which we had to synthesis with the architecture of a HC6805....

I wanted to ask if it was possible to use a XILINX 5202 in a control circuit without synthesing / programming it ? Can a EPROM be used to store its program ?

Just curious .... any clues people ???


05-27-2005, 12:25 PM
FPGA - Field Programmable Gate Arrays ... the name says it all ... it's a general purpose reconfigurable collection of gates.... do whatever u wish with it by changing the program .... yes ... u have to program it .... not a very difficult task ... i guess if u have access to a programmer kit !

I have used the Xilinx Spartan II earlier ... can use it for ur purpose ... but have to program it ... it's not like a microcontroller with a ram / rom .... the program is a configuration information for the connection wires

05-27-2005, 11:21 PM
Hi nchinoy,

I don’t think it’s really possible. EPROM basically conditions logical block configuration bits, which gets loaded in the SRAM of the FPGA soon you switch on the supply. Doing this other way round looks a bit impossible.

05-28-2005, 05:58 PM
Can anyone recommend an inexpensive PDIP package FPGA / CPLD ?

05-29-2005, 11:00 AM
Umm interestingly enough i was under the same impression since i had used XILINX spartan II that a FPGA needs to be synthesised with the architecture that we want so as to configure it....

but i spoke to a official XILINX techie, who works for XILINX in India , its a company based in PUNE... His view was different.... he said that it was possible to use a XILINX 5202 directly without having to program/ synthese it...

I am going to have a detailed chat with the fellow soon... but it seems that this is possible... also about the eprom... well there is a very simple "trick of the trade" when you want to use a EPROM/ EEPROM to give you a output without giving it an input....

Consider this .. the address bus of the eprom comes from the output pins of the XILINX 5202, the Enable/Control Bits are active LOW they also come from the XILINX 5202 and the data bus also goes to the XILINX.. Now if i was to PULL the address bus LOW /HIGH using a PULL DOWN/UP resistor pack, and PULL DOWN the ENABLE bits.. On POWER ON these will become the input to the EPROM with the eable bit low , it will look up the address bus (to find all 000 or 111) and will give me the data at that particular address... This might help as the output to the databus then being fed to the XILINX can start the process.... and from there on XILINX can take control over the EPROM and rest of the circuitary....

Well the last time while i was using XILINX spartan II during my 3rd Year University days ... it was a little different as we had an amazing setup for us ready to use ... ;) and we had slogged our selves to produce a 68HC05 architecture and its Instruction set in the XILINX SPARTAN II ... It was all good fun but now .. i need that setup again and i dont have it ... :(

Anyone of you's have any recommendations for some books on FPGA's ?