Pissed off with Xilinx - Spartan 3

Erik,

OK, thanks for the explanation.

Spartan 2 today is based on a very mature process, and the sequence is 'don't care', and the power on surge is within the specifications clearly outlined in the datasheet.

The Spartan 2E is a much better choice, and is based on the "EA" shrink (hybrid .18/.15u process), and also has no 'sequence issues', and an even smaller power on requirement than Spartan 2.

'Sequence issues' for any Xilinx part all relate to their use: what happens when you plug them into a live bus, anbd what do you expect to happen while you power them ON, OFF, or do nothing. The support through the web technical answers detail all that stuff.

Some parts are more hot plug friendly than others, and none sustain any damage to themselves as long as the absolute maximum voltages and currents are adhered to.

Very few people in your situation are designing boards that are going to be hot-plugged, and even fewer care what happens when you do. For those who do care, we have a full range of documented proven solutions.

Xilinx admittedly does not cater to the home hobbiest, as we don't see much revenue from that source. I am happy to see Xilinx FPGAs being used for software defined radios by amateur radio hobbiests (being that I have the call sign AB6VU, and I am also very interested and involved in SDR for our commercial customers).

I am sure that must be tough going, but most hobbiests realize that buying exiting development boards (like the Spartan 3 student Digilent pcb for $99) is a better choice than trying to etch your own pcb's in the sink.

We do cater to Universities and Schools, as training generations of engineers (since 1985) to use our parts is a very viable business decision. Perhaps stepping on board with those suppliers (like the one mentioned above) is much easier.

Austin

The design I have in mind right now is hot-plugged, but only on the USB side. The FPGA will be glue between the USB chip, DRAM and flash. I'm hoping that the power-up requirements of an XC2S50E or -100E won't require any significant control circuitry. Eventually I hope to reduce the logic requirements to a lot fewer pins and gates, into CPLD realm, but for experimentation I want to have every pin of every device routed through the FPGA, even if half the logic is just crosspointing.

I have this board, and am going to try to do my initial development by building boards to plug into the 40pin connectors, but among other things that limits me afaict to an x8 DRAM instead of x16, due to lack of pins. A x16 JEDEC pinout for 256 or 512Mb has 16 data lines, 13 addr lines, BA0, BA1, RAS#, CAS#, WE#, CLK, CKE, DQML, and DQMH. Total of

1. I'm still figuring out how SDRAM works, but I'm only sure I can tie CKE, DQML, and DQML. That gets me to 36, but there are only 34 I/O's on connectors A2 and B1 of the Spartan3 board...

Flash is easier, only 15 pins. USB I've already done hand-wired using the ELRAsoft EZ-USB FX2 board, and in a manner IMO far superior to the board Digilent sells to do the same thing (I actually connect all the pins... x16 data and control). Already done a basic test design all the way through to user-space software in Linux on that setup (host-controlled PWM of the 8 LEDs).

Erik,

How is USB hot plug to the FPGA? USB may be hot plug to itself, but the FPGA isn't involved.

And, if you pull the USB plug, you disconenct the link, and it stops. If you plug it in, it starts to work. This is not considered hot plug in the industry. Hot plug is when you plug into something already working, and try not to disturb it (generally).

What you are talking about is better called "live insertion" where you are concerned about something breaking if you attach something while the power is on, or detach it when it was powered.

I can't see any issues here with any of our parts, past or present.

If you are attempting to power the FPGA from the USB 5V @ 500 mA, that will be an issue with any part that has a startup current requirement.

We made a USB pcb with a switching regulator (from 5Vdc to 1.5V) for a

2VP4. That is 2.5 W total power available from the USB, and at 1.5V, that is 2.5/1.5 ~ 1.5 amps (derating for efficiency). At 1.8V it is less, and at 2.5V, less than an ampere. This might be an issue for the old parts (see the data sheet).

The USB pcb is the "Logic Vault" board for security experimentation (with 3DES key, 20+ year life lithium coin cell, and a true random number generator IP that runs when you plug it in).

We have passed these out to people who promised to hack and tell us the key, or the bitstream. No one has been able to crack them (yet). Evidently 3DES in V2 and V2P is still quite secure....

Aust> Aust>

What the hell do I need (or WANT) anyone looking over my shoulder? Let me have the parts without the overhead. After the Xilinx web site, I don't NEED anything else but my simulator.

What does a (high priced) distributor actually deliver to me? I'm not working for Boeing or other huge corporation. Digi-Key is the right-sized distributor for me. I look up the part, and order it. Very simple.

Jon

Hi Steve,

To clarify it for me, what is the likely lead times AFTER August for the lower density Spartan3's, eg., xc3s200?

Thanks,

A long time Xilinx customer

Steve Knapp explained: Append 0974 to the order code, and every distributor should be able to quote short leadtimes. If not, contact a better distributor. They are not Xilinx employees, but rather independent businessmen. Xilinx has lots and lots of parts, especially of the 3S200. This is just a logistical snafu, not a real availability problem. Sorry for the confusion. Peter Alfke

Steve Knapp explained: Append 0974 to the order code, and every distributor should be able to quote short leadtimes. If not, contact a better distributor. They are not Xilinx employees, but rather independent businessmen. Xilinx has lots and lots of parts, especially of the 3S200. This is just a logistical snafu, not a real availability problem. Sorry for the confusion. Peter Alfke