Efinix FPGA

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Anyone using Efinix parts?  They look ok, even if they don't have a lot of package offerings.  

The smallest part has a 0.5A surge at power on.  The list it as "minimum", I'm guessing they mean the minimum required by the supply.  

They also don't provide software until you buy an eval board, so no way to check that out, up front.  

Funny company, but not as "funny" as Cologne Chip.  They have a part listed at Digikey, (in stock, too) but no 3.3V I/Os, only up to 2.5V.  

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Rick C.

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Re: Efinix FPGA
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I checked into them a little while back, hoping for 5v tolerance, but
they didn't have it.

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Their smallest board used to be dirt cheap before the chip shortage.  I
got one just to test the software.

https://www.digikey.com/en/products/detail/efinix-inc/XYLONI/13535080

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3.3v I/O is listed in the datasheet for the Trion family, right on the
first page...

https://www.digikey.com/en/supplier-centers/efinix

Re: Efinix FPGA

On 12.07.22 17:23, DJ Delorie wrote:
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Are there ANY FPGAs that have 5V tolerance?
I'm looking for one to replace an FDC9266.

Josef

Re: Efinix FPGA
On Wednesday, July 13, 2022 at 2:31:30 AM UTC-4, Josef Moellers wrote:
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Unless you use a very, very obsolete device, you won't find 5V tolerance in
 any FPGAs.  On inputs, 5V tolerance is easy to add, using just a pair of r
esistors as a voltage divider.  On output,  you will need to use at least a
 transistor to allow switching to 5V.  But if you are working with TTL inpu
ts, you don't need 5V drive, 3.3V drive should be enough.  

There are also ways to use resistors on outputs, to allow higher rise, by g
iving up something on the low end.  What do you need to interface to?  

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Re: Efinix FPGA

On 13.07.22 15:36, snipped-for-privacy@gmail.com wrote:
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It's a very old SingleBoardComputer with an HD64180 and lots of LS TTL  
stuff. I need to interface to inputs (eg DMA requests), outputs (eg  
address lines) and bidirectional (data lines). I am considering using  
level shifters on the latter.

IIRC I had been asking here before and got the same answer you gave  
above, but as DJ mentioned it, I thought I might be lucky today.

As I'm hopefully having lots of spare time in the near future  
(retirement after almost 41 years in the IT industry), I guess I'll put  
it all together and give it a try.

Thanks anyway

Josef

Re: Efinix FPGA
On Wednesday, July 13, 2022 at 9:53:55 AM UTC-4, Josef Moellers wrote:
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e in any FPGAs. On inputs, 5V tolerance is easy to add, using just a pair o
f resistors as a voltage divider. On output, you will need to use at least  
a transistor to allow switching to 5V. But if you are working with TTL inpu
ts, you don't need 5V drive, 3.3V drive should be enough.  
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by giving up something on the low end. What do you need to interface to?
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I like switch based parts for 5-3.3V level shifting.  It drops the 5V power
 rail to 4.3V internally, which is used to drive the gate of the pass trans
istors.  This causes them to not conduct above 3.2V or so.  So the 5V side  
can swing as much as it likes and the 3.3V side is protected.  The 3.3V sid
e can drive the 5V side to 3.3V which is adequate for TTL levels.  

Using this with 2.5V logic doesn't work so well since 2.5V CMOS doesn't dri
ve high enough for 5V TTL.  You have to use real level shifters.  Once you  
open that can of worms, it gets ugly with various parts for unidirectional  
and bidirectional.  How do you control the direction with parts that actual
ly drive?  

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Re: Efinix FPGA

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Here in Europe, there was a lot of RoHS conversions about two decades
ago which in practise meant swithcing to lead free components.  

Re: Efinix FPGA

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Second try. About two decades ago there were a lot of lead free
conversions in Europe due to the RoHS directive and again last decade
when it expanded to medical devices too. So since a lot of old
components weren't available lead free, a lot of substitution was done
and often that meant replacing 5V parts with 3.3V parts and using level
shifters. To be sure, mostly slow interfaces, old microcontrollers
running at 8 or 16 MHz and slower than that serial stuff.

In a bunch of such projects there was never any issue with the level
shifters. Never. They were completely problem free all the time.

As for the direction control, some level shifters have a direction input
and some autodetect. As I recall, the autodetecting ones were fine
already back when.

Re: Efinix FPGA
On Thursday, July 14, 2022 at 7:48:36 AM UTC-4, Anssi Saari wrote:
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I'm not sure what this is in regard to.  Why would you expect any problems from level shifters?  

I'm referring to the proliferation of part numbers for level shifters.  TI must have a dozen families of level shifters.  


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How do autodetect shifters, detect the direction?  I believe this imposes some sort of limitation on the output drive, no?  

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Re: Efinix FPGA
On 14.07.22 18:48, snipped-for-privacy@gmail.com wrote:
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[...]

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I'm only a software person (with a strong hardware interest), but I  
assume that it centers around the fact that on a bidirectional  
connection at any one time only one side is actually driving the  
connection. I'd need to consult an ex-colleague who at that time  
explained the conecpt of this FET-Level-Shifter to me.

Josef

Re: Efinix FPGA
On Friday, July 15, 2022 at 2:10:03 AM UTC-4, Josef Moellers wrote:
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ut  
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s some sort of limitation on the output drive, no?
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I believe the way these work is to wire the two drivers so each one drives  
the other input.  This makes a stable FF arraingment.  The output is throug
h a resistor to limit the current drive.  Then, when one side or the other  
is driven, the resistor on the output (or just a current limited driver) al
lows the external drive to overcome the internal drive and so control the i
nput.  This is reflected on the other output, which drives the other input,
 which switches this side output to match the level driven by the external  
driver.  This also acts as a bus keeper, preventing the buses from drifting
 to invalid voltage levels which can be an issue with excessive supply curr
ent or even damage.  The current limited output can be a problem with fast  
switching the output.  

I think I saw on some fancier parts, where, to deal with the slow switching
, would drive with two drivers in parallel, a high current driver for fast  
switching speed and a low current driver as the "bus keeper".  They used an
 internal timing circuit to disable the high current driver after a short t
ime.  This is a bit fuzzy to me as it was a long time ago I saw this.  

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Rick C.

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Re: Efinix FPGA
On 14.07.22 09:06, snipped-for-privacy@gmail.com wrote:
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[...]

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series for "Elektor" (German hobbyist electronics magazine, german  
edition of Dutch "Elektuur") and there I learned the simple level  
shifter using a FET and two pull-ups. That's what I'll (probably) use,  
at least for the bidirectional signals. As only a one side is actually  
driving, it should work.

Josef

Re: Efinix FPGA
On Thursday, July 14, 2022 at 10:36:04 AM UTC-4, Josef Moellers wrote:
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:  
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ut  
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nce in any FPGAs. On inputs, 5V tolerance is easy to add, using just a pair
 of resistors as a voltage divider. On output, you will need to use at leas
t a transistor to allow switching to 5V. But if you are working with TTL in
puts, you don't need 5V drive, 3.3V drive should be enough.  
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, by giving up something on the low end. What do you need to interface to?
  
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t  
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 drive high enough for 5V TTL. You have to use real level shifters. Once yo
u open that can of worms, it gets ugly with various parts for unidirectiona
l and bidirectional. How do you control the direction with parts that actua
lly drive?

  
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I assume you mean a FET as a pass element with limited pull up capability?  
 That's what I use on a board I have currently in production.  TI SN74CBTD3
384CPW, 10 bits, separate enables for the two 5 bit sections.  Works well.  
 This chip is designed for the job.  There are smaller versions.  Hacking y
our own out of FETs means have to select the FETs with appropriate gate thr
esholds and variance.  This is not normally controlled carefully.   You als
o have to generate the drive voltage for the gate.  That's why they invente
d the such switch parts.  

https://www.ti.com/lit/ml/scdb006a/scdb006a.pdf?ts16%57817753410&ref_url
=https%253A%252F%252Fwww.google.com%252F

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Rick C.

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Re: Efinix FPGA
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The Spartan 3E has an app note for how to add 5V tolerance to their I/O
with a single resistor, but 3E's are becoming scarce.

Re: Efinix FPGA
On Wednesday, July 13, 2022 at 4:11:13 PM UTC-4, DJ Delorie wrote:
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That's just a matter of limiting the current when the protection diode conducts.  However, it also limits speed, from the RC of the limiting resistor and the input capacitance.  

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Rick C.

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Re: Efinix FPGA
On Monday, July 11, 2022 at 8:25:27 PM UTC-4, snipped-for-privacy@gmail.com wrote:
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We are using Efinix due to supply chain shortages to replace Cyclone 10 part.
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The software is OK, but Quartus for Intel/Altera parts is much better.  Haven't used Xilinx in too long of a time to make that comparison.

Kevin Jennings

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