Verilog or VDHL.

[mikeselectricstuff]

Whats the difference between XO2 and XO3?

https://www.eevblog.com/forum/microcontrollers/difference-between-machxo2-and-machxo3/
MachXO2-640U which is available as TQFP is the biggest LUT count of the TQFP form factor at 640 LUTs.
I guess it depends on your requirements. 

You mean XO3 - that's the only QFP option for XO3.

All XO2 sizes are available in QFP (100/144), up to 7000(ish) LUTs, as well as a few small packages ( QFN32,QFN48 and 25-WLCSP)

[legacy]

Don't you happen, guys, to have a spartan2 board for sale? or to know where to get one?
Eight voltage level shifters to interface a spartan3/6 FPGA with a 5V microprocessor bus is  ... annoying for me.

edit:
The same applies to PCI-5V. The PCI-3.3V should better for FPGAs, but unfortunately, my PowerMac-G4 is only PCI-5V. About that, the only good PCI-FPGA kit I have ever found is by MESA.

[NivagSwerdna]

Whats the difference between XO2 and XO3?

https://www.eevblog.com/forum/microcontrollers/difference-between-machxo2-and-machxo3/
MachXO2-640U which is available as TQFP is the biggest LUT count of the TQFP form factor at 640 LUTs.
I guess it depends on your requirements. 

You mean XO3 - that's the only QFP option for XO3.

All XO2 sizes are available in QFP (100/144), up to 7000(ish) LUTs, as well as a few small packages ( QFN32,QFN48 and 25-WLCSP)

I don't think I was concentrating.... sorry.  According to the XO3 Family guide I just downloaded (Jan 2018) the XO3 is WLCSP or BGA.  I stand corrected on XO2... 144-pin TQFP XO2-7000 buys you 6864 LUTs or a XO2-4000 which 84 QFN gets you 4320 LUTS and 68 I/Os.  That last part could be quite handy.  (The QN84 footprint actually has two rows of pins so might be challenging for hand assembly... looks more feasible than BGA though)
Sorry for the confusion.

[NorthGuy]

I think 1mm (or 0.8 mm for that matter) BGA package may give you better yield than 0.5mm TQFP. I don't have PnP, but the placement accuracy should depend mostly on the pitch not on the geometry of pins/balls.

BGAs are also the easiest for prototyping. I just apply flux, place the BGA and apply heat. You only need an oven or an air gun with wide enough nozzle. This is much easier than dealing with QFNs.

[asmi]

I think 1mm (or 0.8 mm for that matter) BGA package may give you better yield than 0.5mm TQFP. I don't have PnP, but the placement accuracy should depend mostly on the pitch not on the geometry of pins/balls.

BGAs are also the easiest for prototyping. I just apply flux, place the BGA and apply heat. You only need an oven or an air gun with wide enough nozzle. This is much easier than dealing with QFNs.

I totally agree! I've never had any soldering issues with BGAs, while QFNs still give me grief every once in a while. And two-row QFNs seems like even worse than regular QFN, though I haven't tried using them yet.

[SiliconWizard]

QFNs are awful for hand-soldering in terms of yield. For sure.

But QFPs? Never had any problem with them at 0.5mm pitch. Obviously while soldering you'll get some bridges that you remove with solder wick and you're done. The big plus is that you can visually inspect them, and when in doubt, again you can use solder wick. With QFNs it's already much harder to visually inspect, and harder to remove excess solder especially when it's trapped behind the pads. When they have a central thermal pad (which most of them have), it's a PITA. It makes it very hard to keep the QFN flat and then makes it hard to have good contact with all pads.

I have honestly never tried hand-soldering BGAs, except very low-pin count ones. Many people say that BGAs are easy to solder, and I'm willing to believe that, but I'll have to try one of these days. The real issue I see with them is again visual inspection. Apart from the outter balls row, you just have to cross fingers.

[Fred27]

I like QFP. I struggle with QFN. I've been too scared to even try BGA! I'm just looking at getting into FPGAs and solderability is one of my priorities. More so than performance as I'm likely to be doing very basic things with one.

Verilog or VHDL? I like the feel of Verilog better so far, but will probably give both a proper try out.

[james_s]

I really do need to try a BGA one of these days, I have an xray machine I could use to inspect it. The limiting factor for me has been that most BGAs require a multilayer board which until fairly recently has been very expensive.

[asmi]

I really do need to try a BGA one of these days, I have an xray machine I could use to inspect it. The limiting factor for me has been that most BGAs require a multilayer board which until fairly recently has been very expensive.

Try getting some QSPI flash chips in BGA package (like S25FL116K0XBHI030, which are EOL, but still are available at about $0.50 apiece). These are in 1 mm pitch BGA-24 package, but the pinout is such that you can route out SPI on 2 layer board, and you can use FTDI's MPSSE 3.3V cable to talk to these chips using SPI (QSPI chips support regular SPI as well) to verify that soldering went well. This way you can practice BGA soldering on cheap - get a dozen or so of these chips, design a simple 2 layer breakout for it, order boards at Chinese fab of your choice, order cheapest frameless stencil at the same fab (most of Chiness fabs also offer cheap stencils) - and give it a try! This whole exercise will cost you less than $50 for everything, and provide you ample practice to see by yourself that BGA are not nearly as hard as some people (most of whom never actually tried!) make it out.
As for multilayer boards - my recent order at WellPCB for 10 6-layer boards 10x10 cm with custom stackup and impedance control on all signal layers was only $195 with shipping included in this price. I think it's a bargain as the same board in US would cost over $1000!

[james_s]

Yeah multilayer boards have really come down in price, but they're still relatively expensive. That same size board in single layer double sided would be 1/10th the cost.

[asmi]

I like QFP. I struggle with QFN. I've been too scared to even try BGA! I'm just looking at getting into FPGAs and solderability is one of my priorities. More so than performance as I'm likely to be doing very basic things with one.

I'm actually contemplating designing a simple 4 layer breakout board for cheapest Spartan-7 FPGA and sharing it here so people can just take my Gerbers, order boards (4 layer boards are cheap nowadays!) and build boards themselves. This way they can get known-working board design and make some useful breakouts for them to play with, so at least this will eliminate board-related issues, and known-good schematics will give them a jump start designing their own boards knowing that basic critical connections are already made and working as they should. I know I would've benefited from such design back in a day when I was designing my very first Artix-7 board, as it took me 2 revisions to get my FPGA to be recognized by the programmer.
I've built a bit more advanced breakout for Artix-7 FPGAs, but it's a 6-layer board so I imagine fewer people would be interested in it, unless I mass-order boards (since tooling cost is already paid by me, additional orders would be much cheaper than what I've paid for the first run) and mail them out.

[asmi]

Yeah multilayer boards have really come down in price, but they're still relatively expensive. That same size board in single layer double sided would be 1/10th the cost.

True but this is not really a fair comparison as 6 layer board allows you to do much more than you can ever do with 2 layer one.
More importantly - unless you need to have high-speed things like DDR3 on your board, you can get away with regular 4 layer boards, which are only $32 at JLCPCB. For example, Spartan-7 is available in 1 mm pitch BGA-196 package which was specifically designed to be fully routed out on 4 layer board, and you can do quite a bit using these FPGAs (pretty much everything you can do with Artix-7, except when you need a lot of DSP tiles, or MGT transceivers, but latter will require impedance control anyways).

[SiliconWizard]

@asmi: sorry to hijack the thread (and I think we already have quite a bit), but since you have experience with the Spartan-7, would you happen to have some kind of fair comparison between the -7 and the Spartan-6? I'm still using the -6 in some of my designs but I've been considering the -7 line. Was just under the impression that the Artix-7 was a closer match, but unfortunately more expensive.

[iMo]

FYI - I got a couple of these boards - actually a little bit newer revision (with FT230X and jtag buffers), 4 layers pcb for $30 incl. shipping each. Thus 4 layers are doable cheap, it seems..
PS: "9k Logic cells" in Spartan6 LX9 mean 1430 slices, 1 slice = 4LUTs with 8FFs.

[NorthGuy]

I'm still using the -6 in some of my designs but I've been considering the -7 line. Was just under the impression that the Artix-7 was a closer match, but unfortunately more expensive.

ISE supports few Artixes such as A7100T, so you can change the chip and run your designs and see the differences. Then you can get the same design to Vivado, which also supports A7100T, port your project (you will have to re-write constraints and pin assignments), and see how it compares to ISE for you, perhaps compare the results.

[SiliconWizard]

ISE supports few Artixes such as A7100T

Actually I didn't realize that! Thought ISE would not support the -7 line at all. Just checked ISE and you're right.
ISE supports the XC7A100T and 200T and Kintex-7 70T and 160T.

I happen to have a board with an XC7A35T which unfortunately is not supported.

Anyway, I'm more interested in comparing with the Spartan-7. The Artix-7 is very capable compared to a Spartan-6 but much more expensive. An XC7A35T is currently $49 at Digikey and a 100T at $176 !!

[NorthGuy]

Anyway, I'm more interested in comparing with the Spartan-7. The Artix-7 is very capable compared to a Spartan-6 but much more expensive. An XC7A35T is currently $49 at Digikey and a 100T at $176 !!

Spartan-7 is exactly the same as Artix-7 except that it doesn't have MG transceivers and the pinouts are more user-friendly, however it doesn't have -3 speed grade. None of Spartan-7 are supported by ISE.

[asmi]

@asmi: sorry to hijack the thread (and I think we already have quite a bit), but since you have experience with the Spartan-7, would you happen to have some kind of fair comparison between the -7 and the Spartan-6? I'm still using the -6 in some of my designs but I've been considering the -7 line. Was just under the impression that the Artix-7 was a closer match, but unfortunately more expensive.

I don't (yet) have any practical experience with S7 as I'm still designing my first S7 board (to drive 64x32 LED panel, as Artix seems like an overkill for this task, and all boards I've designed so far have Artixes), but you can easily compare them by looking at their datasheets. Essentially Artix-7 is a replacement for S6-LXT and S7 is a replacement for S6-LX. Advantages of 7 series (compared to S6) are:
1. the size of BRAM is doubled to 36k, it supports up to x72 data width (compared to 18k and x36 respectively in S6)
2. BRAM is about twice as fast in 7 series (Fmax is 297.5 MHz on speed grade 1 in ECC mode vs 150 MHz).
3. BRAM is 7 series can be configured as FIFO with no external logic required, and Fmax in this configuration is 388 MHz for SG1.
4. DSP blocks in 7 series are about twice as fast (Fmax is 464 MHz vs 213 MHz)
5. Global clock buffers (BUFGs) are also almost twice faster (Fmax is 464 MHz vs 250 MHz).
6. S6 has dedicated DDR memory controller blocks, while 7 series does not - instead DDR2/3/3L controller is implemented in fabric, which has it's own pros' and cons'.
7. S7 doesn't have any MGT transceivers as this functionality is only available in Artix, though A7's MGT support up to 6Gbps while S6-LXT only goes up to 3Gbps).
8. SERDES are also about twice as fast on 7 series.

But the most important advantage of 7 series IMHO is 100% vertical compatibility which allows you to migrate the same design up and down along S7-A7-K7-V7 families as needed, because all HW blocks are identical all across families, with exception of MGTs of course.

[SiliconWizard]

Thanks.
Spartan-7's are still significantly more expensive than the 6's for an equivalent number of logic elements. Of course 6's are still available as of now, but for how long? I'll certainly miss them. The 7's prices are probably going to decrease over time though, I suppose.

[mikeselectricstuff]

Spartan-7's are still significantly more expensive than the 6's for an equivalent number of logic elements. Of course 6's are still available as of now, but for how long?

Plenty of spartan 2 parts are still shown as active at Digikey.
FPGAs are long-lifetime products,so I wouldn't worry too much, though the odd specific part may be obsoleted if there is little demand.
And older parts may get more expensive.

[asmi]

Thanks.
Spartan-7's are still significantly more expensive than the 6's for an equivalent number of logic elements. Of course 6's are still available as of now, but for how long? I'll certainly miss them. The 7's prices are probably going to decrease over time though, I suppose.

I just checked Digikey, and it seems that they are not. XC7S6-1FTGB196C (6k gates) is $19.2 CAD while XC6SLX4-2TQG144C is $17.12 CAD (3840 gates). So I'd say they are even. On a high end - XC6SLX100-2FGG484C is $184.99 CAD, while equivalent S7 XC7S100-1FGGA484I is $163.73 CAD - so S7 is even cheaper, despite it's being faster and wider temperatures range.
So I'm not sure where did you see S7's being "significantly" more expensive. From what I see they are priced more-or-less on par with each other. By undercutting themselves it seems that Xilinx really wants their customers to move onto 7 series devices.

[NorthGuy]

If you go to higher speed grades (-2) of Spartan-7 and Artix-7,  the clock can go up to 625 MHz (even to 680 MHz with BUFIO), so you can do really fast LVDS.

[SiliconWizard]

I just checked Digikey, and it seems that they are not. XC7S6-1FTGB196C (6k gates) is $19.2 CAD while XC6SLX4-2TQG144C is $17.12 CAD (3840 gates). So I'd say they are even.

Oh, right. I probably still had the Artix-7 prices in mind. Seems like the price gap is even larger on the bigger ones (in favor of the 7).

[asmi]

If you go to higher speed grades (-2) of Spartan-7 and Artix-7,  the clock can go up to 625 MHz (even to 680 MHz with BUFIO), so you can do really fast LVDS.

But unfortunately still not fast enough for 1080p HDMI At least not officially - I know there is a way to make it work, but it's kind of hacky

[mikeselectricstuff]

I just checked Digikey, and it seems that they are not. XC7S6-1FTGB196C (6k gates) is $19.2 CAD while XC6SLX4-2TQG144C is $17.12 CAD (3840 gates). So I'd say they are even.

Oh, right. I probably still had the Artix-7 prices in mind. Seems like the price gap is even larger on the bigger ones (in favor of the 7).

Don't forget that Digikey prices for FPGAs  bear little resemblence  to actual  prices,even at lowish volumes,  once you get into the whole "supported pricing" wierdness.