Looking for an extremely cheap FPGA board (in quantity, academic use)

Hi all, I'm looking for a sub-$20 FPGA board (including everything needed to actually use it). Requirements: * The device must have reasonable free software that can handle schematic capture and Verilog (Altera and Xilinx would be easily sufficient). * Can manage at least 1K gates and 20 flip-flops.

Strongly desired: * At least one debounced button useable on a GPIO line (not reset for example) * At least six switches readable by the FPGA. * At least six LEDs writable by the FPGA. * At least four GPIO pins that are reasonably accessible. * Actually costing closer to $10. * Can power off of USB without any other supply. * Can manage at least 5K gates and 50 flip-flops.

Would prefer: * At least twice as much I/O as described above. More is better. * Compatible at some level with some larger FPGA line (Altera DEx line in an ideal world).

I'm going to go vendor shopping in a few weeks, but I thought I'd see if anyone knows of anything close to this that's on the market.

We'd be looking at around 5K-15K ordered, all for academic purposes. Failing finding a board, we are willing to design and manufacture our own (as a far second choice). So suggestions on parts would be welcome.

Also, any thoughts on using a cheap microcontroller to emulate an FPGA would be of interest.

I've found some things that aren't all that close. * Digilent C-Mod -- $22 in quantity of 1, needs external programmer, no I/O on-board AFAICT. * Polmaddie2. No switches, way too much $$$, but pretty good otherwise. Way more GPIO/FPGA than we need.

Thanks in advance, Mark

Reply to
brehob
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use it).

The closest I've seen is a number of Lattice eval boards like the MachXO2 "Pico" board for about $29. I've always suspected that the price of these boards is already somewhat artificially low in order to win seats for their devices. It's not clear that you will get a better price in volume, but I would think Lattice is a good place to start for low cost FPGA's or boards.

Regards, Gabor

Reply to
Gabor

When you get as far as vendor-shopping, don't forget Avnet. I think most of their stuff starts at $100 and goes up from there, but you never know.

Ditto SparkFun, for the opposite reason -- if they had anything FPGA, they'd probably have something in the price range you want. But I wouldn't bet anything that they actually have that.

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Reply to
Tim Wescott

The Pico board has many unecessary components, like the FTDI chip, accelerometer and the 1.2 V voltage regulator.

There are Lattice FPGAs with 3.3 V only. The LCMXO2-640HC-4TG100C for $4.72 at Digikey should be sufficient. It has 640 LUTs, so it should be possible to implement 1k gates with it (because sometimes multiple gates can be integrated in one LUT). 50 flip-flops is no problem at all.

For the USB connection you could use the MC9S08JS16L, which I've used for

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and which costs less than $1. This microcontroller can program the FPGA at boot time, if you add a SPI flash for $2, or without a Flash just from the USB port. Crystal oscillator, DIP switches, LEDs etc. should be less than $10 for all parts, so $20 for a fully populated PCB should be possible, if you develop it yourself. A smart student could do it, to save development cost.

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Reply to
Frank Buss

// Snip

It would seem that if this board is for "academic use" you could have a student design this for you and as a class project have it built by the students.

You really need to pick a chip that meets your "class room" requirements for functionality first.

Not cost first.

Also,

What do you expect to teach.

Just like in any product development, What do you expect to do with this thing, who do you expect to sell it to.

My $0.02

hamilton

Reply to
hamilton

t.

Yep, I'm guessing we will have to design it ourselves, but I'm hoping to find something off-the-shelf (always ideal if what you want already exists). That said, we'll probably need to design it ourselves so we'll need to find parts. Your suggestions are a good starting point, thanks! The LCMXO2-640HC-4TG100C is a bit more than we need in terms of I/O and memory, but otherwise looks nearly ideal.

Still hoping a board exists...

Thanks, Mark

Reply to
Mark Brehob

Yep, that's the backup plan.

Sadly, the top-level requirement is likely going to be cost. That is, we'll have a fixed budget and need to do as much as we can within that budget. I agree it's not the ideal way to proceed, and the amount for the fixed budget is unclear at this time ($10-$20/unit is a safe bet though).

What we are doing right now is exploring if we can possibly do the labs we want to do given the budget we think we have. The key question is "is this doable given the cost constraints", where "this" is mildly flexible (thus the I/O constraints being only rough).

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is what we _want_ to do. Right now on a DE2 board. The labs cover the standard basics as well as a bit of interfacing. Some parts of the labs as written are the way they are because of the board we have.

What: the labs above (with some reduced I/O requirements including losing the 7-seg displays). Who: Anyone taking the class on-line, including those with extremely limited budgets (third-world).

Mark

Thanks!

Reply to
Mark Brehob

Actually the FTDI chip is the programming adapter as well as a serial port for this board. The original desire was for a board that came with everything required to program it. In this case the PicoBoard is powered by USB, and programmed with the same USB adapter. It may not have needed the serial port, but I'll take it as an added bonus.

All of the analog stuff is just so they can demo the "low power" of the MachXO2 part. You could always ask for partially stuffed boards if you want to get into a volume deal. The capacitive buttons are also unnecessary, but better than no buttons.

In any case an FTDI chip (maybe a simpler one than that on this board) is usually a good idea when you want the board to be programmed without an extra JTAG cable (usually much more expensive than these boards).

Reply to
Gabor

This is always the argument with commercial products too.

But you still need to have a spec!

Lets be real, your on a shoestring budget with a DE2 diet ;-).

The PCB and pin headers will burn thru half of your $20.

A board with one chip onboard (i.e. LCMXO2-256HC-4TG100C $3.40 100s), a USB connector, a 3.3V voltage regulator, a few loose passive parts and you are done.

I would enjoy building a board like this, but I do not have an advertising budget to pay for it.

Digikey part# ea@100pcs total

220-1425-ND 3.40 340.00 LCMXO2-256HC-4TG100C ED90341CT-ND 0.92 92.00 CONN RECEPT MINI-USB TYPE B SMT 497-1236-1-ND 0.287 28.74 IC REG LDO 3.3V .95A D-PAK PCB (2.5" x 2.1") 8.50 850.00 PCB I had quoted with PCBcart a few weeks ago A26509-40-ND 1.402 140.25 CONN HDR BRKWAY .100 40POS VERT

total 1,450.99

Here is $14.51 per board for most of the components.

There may be some savings here, but the remaining passive components will take care of that.

If I were to build a board like this, I would have to charge 3x the cost of parts to make it worth my while.

And I would require you to buy all 100.

On the other side of the coin:

Digikey part# Qua = 1

220-1298-ND $29.99 BOARD BREAKOUT MACHXO2

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Has all you want, and they have an advertising budget.

This sounds like a great opportunity to teach a little entrepreneurship.

This was a fun exercise, maybe you can use it in your class.

I bet you can write on your school letter head and ask for 100 samples of each of the parts.

You will still need to design a PCB and have it fabricated.

Good luck

hamilton

Reply to
hamilton

I think you're in luck...

I was browsing around earlier today trying to figure out if I could do realtime video-rate JPEG encoding on a DSP instead of having to code it up in verilog, and ran across this...

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For $20, you get:

- 4 capacitive buttons. I guess you still have to 'debounce' capacitive buttons... - 63 i/o on breadboard-friendly 0.1" headers. You'll have to supply the headers. - can power off the USB - has ~1K logic cells (lut+flip-flop) - comes with USB cable & software can be downloaded.

Assuming you can solder some headers onto the board, switches can be replaced by jumpers, and 63 i/o is actually really generous at this sort of level. Most of the entry-level boards are seriously miserly in comparison.

On the downside, you'd probably not get much of a bulk discount - I'm guessing they're already cut to the bone at this price...

Just FYI - not a recommendation since I've never used Lattice before, but thought you'd be interested.

Simon

Reply to
Simon

hamilton wrote:>

Is the $8.50 the price for the PCB only, without reflow soldering of the components? Would be expensive. Even just 10 boards are much cheaper here (double sided)

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And how do you program the FPGA? I don't think that you can attach the USB port to the MachXO2, you need at least a chip to convert the differential signal to digital, but you can't fit a full USB device logic inside such a small FPGA, if you want to do some other useful things with it. I would add a $1 USB microcontroller, but this means some software development.

For the requested number of >5k devices of course it gets even cheaper, because usually there is some setup cost of $500-$1000 for reflow soldering and the parts get cheaper, too.

--
Frank Buss, http://www.frank-buss.de
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Reply to
Frank Buss

actually use it).

Having been struggling with the MachXO2 for the past few months, I'd suggest doing a thorough eval before jumping in with both feet.

While it has a lot of nifty advertised features, not all of them work well, and some (i2c slave) are quite badly broken. Documentation is mostly okay, but very spread out and not indexed well, with some rough spots.

While this is a fine introduction to the life of a working engineer, it may get in the way of the concepts you're trying to teach :-). The basic IO, logic and ram functions seem to work as expected, these seem to be mostly copies of previous generations.

Their no cost licenses are valid for one year, so they may also change their policies on 'free' licensing or the included tool set at some future point and leave you with no good way out.

Reply to
AMDyer

The board I had quoted was for a four layer board (RHOS). My error, the PCB I had quoted was also a 3x3 panel. So the cost per board would be half what I figured. ( I was using a 2x2 panel in my original calculation)

I did not look up how the LCMXO2 was programmed, so some sort of programmer will add a few more dollars.

The 3x cost multiplier was to include reflow of the boards.

Quoting a PCB project can get complicated without a spec to follow.

There is also a bottom line here.

Who is going to put up the capital to have these things built.

Some one like myself would have to put up over $2,000, with no guarantee of sales.

With out a spec to follow, the customer may not like what I built and I would have to sit on these things.

So I may be out $2k, not a good business model. ;-)

Reply to
hamilton

doing a thorough eval before jumping in with both feet.

and some (i2c slave) are quite badly broken. Documentation is mostly okay, but very spread out and not indexed well, with some rough spots.

get in the way of the concepts you're trying to teach :-). The basic IO, logic and ram functions seem to work as expected, these seem to be mostly copies of previous generations.

policies on 'free' licensing or the included tool set at some future point and leave you with no good way out.

I think the license question is no problem, unless Lattice, Altera and Xilinx all decide to change it.

--
Frank Buss, http://www.frank-buss.de
electronics and more: http://www.youtube.com/user/frankbuss
Reply to
Frank Buss

doing a thorough eval before jumping in with both feet.

and some (i2c slave) are quite badly broken. Documentation is mostly okay, but very spread out and not indexed well, with some rough spots.

get in the way of the concepts you're trying to teach :-). The basic IO, logic and ram functions seem to work as expected, these seem to be mostly copies of previous generations.

policies on 'free' licensing or the included tool set at some future point and leave you with no good way out.

I've been down this road with Lattice before. The license "expires" in a year but they can renew it indefinitely because there is no additional cost to them. They can also license it to as many computers as you wish so don't worry about what happens when you replace that old laptop. You won't get updates after the first year which can be a blessing actually. If it ain't broke...

I haven't tried the new Diamond software yet.

Rick

Reply to
rickman

Well, since the OP's logic requirements are so low, he might look at the Xilinx XC95xxXL and XC2R "CoolRunner" CPLDs. The smallest of these devices run slightly over US $1, and have over 30 I/O pins. You'd need something to handle the USB-JTAG conversion for programming, there are a number of chips that can do this. I use the Xilinx Parallel Cable III, which is just a 74HC125 and about 6 small components (res, cap, diode) and the schematic is online. If your project doesn't actually need USB connectivity, you could build the circuit of the Parallel Cable III onto the board for under $1 in parts. It only connects about 5 wires to the PC parallel port. These CPLD chips have a bit different architecture than an FPGA, but the Xilinx tools handle all the synthesis and mapping anyway, so it doesn't matter much. They are more efficient for wide gates like address comparators, but have fewer FFs than an FPGA. Still the 9536 has 36 FF's, the 9572 would have 72. I think the coolrunner comes with 64, 128 and up.

Jon

Reply to
Jon Elson

If you build the Parllel Cable III into your product, what will you connect it to? I don't think they have built a PC with a parallel port in a number of years and my understanding is that the drivers for USB parallel ports don't work properly with bit banging software like this. Am I mistaken? Is this a workable solution?

Rick

Reply to
rickman

I have no idea about the USB-parport, but you CAN get computers with real parallel ports, just not on laptops. I use the parallel port for lots of interconnect projects, and the Intel D525 chipset still has parport support, if the motherboard maker chooses to bring it out. For this reason, we use a lot of Intel D525 (Atom) motherboards in projects.

Jon

Reply to
Jon Elson

ggest doing a thorough eval before jumping in with both feet.

ell, and some (i2c slave) are quite badly broken. =A0Documentation is mostl= y okay, but very spread out and not indexed well, with some rough spots.

may get in the way of the concepts you're trying to teach :-). =A0The basi= c IO, logic and ram functions seem to work as expected, these seem to be mo= stly copies of previous generations.

their policies on 'free' licensing or the included tool set at some future = point and leave you with no good way out.

h
u

Humm, it's sounding like Lattice is going to be the way to go unless I can get support from Altera or Xilinx (something I'll pursue if this gets out of the "idea" stage).

Has anyone worked with Lattice Diamond? How does it compare to the software from Xilinx and Altera? I've been burned by some "bad" FPGA software in the past (not horrible, just too steep of a learning curve for the classroom) and would _really_ like the ability to do schematic capture in addition to Verilog...

Thanks again to everyone for their responses, this has been really useful! Mark

Reply to
Mark Brehob

rt

Yeah, sadly for us we have no control at all over what computers people use, so we can't rely on parallel ports...

Thanks!

Reply to
Mark Brehob

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