Using FPGA to feed 80386

Because the guy who is developing this laser etcher looks like he has high skills. You see the multiple boards, the programming involved, understanding a great many disciplines and bringing them together. Plus, on his first video, he shows the filter lenses and posts a splash screen warning about the dangers of laser light.

Best regards, Rick C. Hodgin

Reply to
Rick C. Hodgin
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Sure.

What about the people that make or use such a device?

There are too many ignorant and/or stupid people around.

Reply to
Tom Gardner

Nope. You are probably too low by a factor of *~100*. Hint: the clock frequency is completely irrelevant.

Nope, not even close. Hint: your circuit will have significant energy at GHz frequencies.

You would be advised to read all the manufacturer's app notes. For example Xilinx, for one family, has UG922 and UG483,

150 pages which are aimed at experienced PCB designers.

I hope by now you are considering buying an FPGA board and adding your circuit to it as a daughter board or carrier board. Ensure the connectors are impedance controlled and have good grounding: many don't.

Reply to
Tom Gardner

My project involves building a 386-like CPU. I do not anticipate it will run beyond 33 MHz to 40 MHz.

I don't intend on running at GHz frequencies. In fact, I'd like to ultimately manufacture my CPU on 5,000 nm process technologies as were used in mid-1980s.

I appreciate your input. My design plans are to use the Altera FPGA I've purchased, to connect an Ethernet board I've purchased and get it running, and then develop from there. It will be all logic within the FPGA at first. That will take time, and during that time I'll be in a position to ask questions, read, learn, etc.

We'll see though... I am currently iterating through ideas, trying to figure out how best to serve the Lord with my efforts.

Best regards, Rick C. Hodgin

Reply to
Rick C. Hodgin

Your problem here is that you don't know the basics of designing schematics or pcbs for FPGAs. People spend years at university learning this sort of thing, then years of full-time professional work before they consider themselves competent. It is not reasonable to expect that you can start from scratch and put together a half-decent FPGA board based on nothing more than hints and advice from a Usenet newsgroup.

A key issue here is that you are thinking about digital hardware, when in fact this is all high-speed analogue. Designing /digital/ hardware, such as the Verilog/VHDL code in the FPGA itself, is pretty simple - it's all ones and zeros, and if you can get your head around clocking, flip-flops and latches (and how to avoid them!), and keep to a single clock domain, then it's not hard to pick up.

But pcb design is analogue. You think your clock signals switch at 40 MHz, so your maximum frequency is 40 MHz - in fact there are relevant parts of that signal up to 400 MHz and beyond. You think your power lines are at 3.3V (or whatever) - in reality, they vary and contain significant signals at different frequencies, amplitudes and phases. You think the 3.3V line is the same across the board, because it is DC - it will in fact vary in DC and AC components throughout the board, in a way that can easily be relevant if you get it wrong. You think that when a pin drives high or low, the whole signal track goes high or low - on a fast pcb, the transmission time is relevant, as are reflections as the signal moves along the track.

I've no doubt that you could learn all this stuff - or at least, learn as much as you need to know. But it will take time, and it will take trial and error - which can become very expensive with FPGA's. That is why you are strongly recommended to buy an FPGA board, and limit your pcb design to daughter boards for it (preferably avoid that too). Come back to the fpga pcb board design later when you have the time to spend on it.

Reply to
David Brown

I appreciate everyone's advice. I'll let you know how it turns out. I'm still filtering ideas about how best to proceed, to use the talents I possess, and the things I desire to do, in service to the Lord. I desire from within to be a good servant, and to not waste my time on things which are beyond me. But I also know that in Him, ALL things are possible, and that He works through communities. It will never be me doing any of these projects alone forever. It will be me doing as much as I can, and then turning to Him in prayer for help. If He helps me I'll proceed. If not, then I'll move on to the next thing.

It is a servants heart for Him... that is why I proceed on these paths. I desire to have the foundations be rooted in Him, which is why I'm looking to 30-year old process technologies and design goals. These are likely attainable today without too much trouble. It will just take time and collaboration unto Him.

Best regards, Rick C. Hodgin

Reply to
Rick C. Hodgin

You appear to have missed my hint. Here it is again: THE CLOCK FREQUENCY IS COMPLETELY IRRELEVANT.

If you use a modern FPGA then you *will* have frequencies in the GHz region. How many GHz depends on the FPGA, IO standard and drive strength.

Hint: google for risetime and knee frequency.

So what? You *will* have GHz frequencies present.

Even if the max frequency is only 500KHz, you would benefit from googling for transmission line, ground plane, inductance, slot, ground bounce in the context of PCBs.

Unless you are exceptionally perceptive, you will make several iterations of that PCB, and unless you understand the cause of the failures, random iterations/permutations will probably be ineffective.

Reply to
Tom Gardner

Actually you are mixing 30 year old technologies with recent technologies (modern FPGAs). Guess which puts more stress on PCB technology?

Reply to
Tom Gardner

A focus:

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"I can do all things through Christ which strengtheneth me."

And a thought to consider:

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"He that is not with me [Jesus] is against me; and he that gathereth not with me scattereth abroad."

Have you received the Lord as your personal savior? If not, I advise you to learn of Him. The gospel message (the good news) is that we need not perish eternally. Jesus Christ has come to the Earth to make a way back for us to be restored to God eternally in Heaven. It is through His Atonement of sin at the cross. Because He had no sin, and because of His Love for us, He took on our sin at the cross and died with it. The punishment that was due us was given to Him, so that we might be made spotless and blameless before God, allowing us to enter in to Heaven. Without us receiving His free gift of salvation, our sin remains upon us, and we must pay the price of our iniquity.

Jesus is the most important person you can ever come to know. I advise each of you to seek Him from within, just you and God. When the TV is off, when the music is silent, when there are no distractions, listen to that still, small voice on the inside. God desires to know you, and to save you from the punishment due you from your sin.

----- As for this forum...

I appreciate everyone's advice. I view a lot of that advice as overt negativity and down-putting rather than an effort toward helpful assistance. As such, I will depart this group now and continue on in service to the Lord on my own. In Him there is hope, guidance, life, and peace. His is the better place to be as the people who seek Him look to build each other up, to help each other out, and not cut each other down. This is the difference between people who pursue Jesus Christ, and people who pursue anything else.

Our life has a purpose and a name: Jesus Christ.

Seek Him, to learn of Him, that He may set you free from the falseness of this world. Peace.

Best regards, Rick C. Hodgin

Reply to
Rick C. Hodgin

There is a middle road.

Get a copy of Eagle or KiCad, lay the board out, and get Gerber files. Gerber files are universal, unlike the captive software that you're talking about.

Then send the Gerber files to a board aggregator (i.e.,

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Oshpark charges $5.00 per square inch and sends you three boards, which is not a bad price at all. You'll only get a 2-layer board, which may not be enough. They also do 4-layer, for more money and slower service.

You're definitely diving off the deep end without a life preserver, here

-- would your experience be more complete if someone tied you up in a bag before you jumped into the water?

--
Tim Wescott 
Wescott Design Services 
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Reply to
Tim Wescott

Wow, are people really like that?

I read this group regularly because I learn a lot from the frequent contributors who clearly have a great deal of practical experience. And I appreciate the fact that you're willing to share your knowledge with those of us who need some help. This guy has gotten a large amount of useful expert advice (for free!), and then tells the whole group that we're rude and not really worthy humans unless we agree with his beliefs.

I can't really comment on the falseness of the world, but I sincerely hope that he remains free of the falseness of this newsgroup for ever after.

Reply to
chrisabele

Unless you use a fab house that uses crap software like ITEAD. The use software the mucks up the images for Gerber files which use certain constructs. They will remake the boards correctly, but it's a PITA. They are cheap though.

He's not diving off anything. He is just testing the waters by sticking his toe in and asking us how it feels.

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Rick
Reply to
rickman

I guess I do. I wouldn't have expected it to be green. Given that it is be whacked by a laser, I'm not sure I would expect any color to show up. Is this forming some oxide of copper that resists the acid? Or has the board been sprayed with a photosensitive agent?

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Rick
Reply to
rickman

...snip...

I think this says a lot more than any of the religious stuff. If he isn't "understood" we are being negative. The reality is that he has a

*lot* to learn and is asking questions. I don't have a problem with that. But when he doesn't like the answers he gets he retreats into his cave of god and lets us know it is our problem not his. That's just being immature.
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Rick
Reply to
rickman

I think he'll be back.

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Rick
Reply to
rickman

See Hodgin's posts in comp.arch; the followed a similar pattern and conclusions.

The major difference was that he did a *lot* more proselyting (and wouldn't stop). Sadly this appears to have been the consequence of some unspecified Bad Events in his life.

I hope we have enabled him to concentrate his efforts on something that stands a chance of being successful.

Reply to
Tom Gardner

The only part of that I disagree with is "being immature". based on his comp.arch posts, I suspect it is more complex than that.

Reply to
Tom Gardner

WOW, another right wing nut case !!

Hey Rick, when you go off the deep end will you find a chocolate shop to visit ??

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Reply to
hamilton

Right wing? His comments were religious. The right wing label is political. What is the connection here?

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Rick
Reply to
rickman

Ok. I won't argue. I don't mind his questions as well as his misplaced enthusiasm. I also think some of the comments here were a little hard on him. If he really wants to learn some things I'm happy to help.

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Rick
Reply to
rickman

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