Cheap 250Mbs Link between Boads

[BrianHG]

the duty cycle is (barely) within limits for 200MHz, the PLL only uses rising edge why else would it have such a wide allowable duty cycle range?
but you can divide input before the pll

The DLL has this divide by 2 on it's input built into it's circuitry.  So, no noise & phase error based on using a logic cell to divide the input by 2, then feed the PLL.  It was specifically designed for this purpose giving us that guaranteed 50:50 duty cycle.  It is literally a hard parameter switch for the DLL separate of the normal divide and multiply parameters where the compiler may bypass your divide by 2 in the m.n settings to optimize the PLL's performance.

[BrianHG]

https://docs.amd.com/v/u/en-US/spartan6_hdl
DLL 'DCM_SP', see parameters page 86.

Parameter:
CLKIN_DIVIDE_BY_2 -  TRUE or FALSE.

What do you think this was designed for?

Remember, this is separate of parameters:
CLKDV_DIVIDE
CLKFX_DIVIDE
CLKFX_MULTIPLY

[langwadt]

https://docs.amd.com/v/u/en-US/spartan6_hdl
DLL 'DCM_SP', see parameters page 86.

Parameter:
CLKIN_DIVIDE_BY_2 -  TRUE or FALSE.

What do you think this was designed for?

Remember, this is separate of parameters:
CLKDV_DIVIDE
CLKFX_DIVIDE
CLKFX_MULTIPLY

I didn't use DCM_SP, I used PLL_BASE (optionally feed by a clock input buffer that can divide)

[ali_asadzadeh]

Guys thanks for the feedbacks.

If the op want to continue with a clock embedded into every transmitted bit going out, then I need him to verify if the OSERDES2 can do 6:1 instead of 4:1 or 8:1.

Yes they can work.

With 2 channel com, he could have gone with a $1.50 Efinix FPGA.  (800mb peak LVDS)

I'm all ears? what part do you suggest?

but why why why restrict yourself to Spartan 6 ? A part from 15 years ago ?
There are plenty of easy to use modern parts...

Why design a product for a customer using obsolete parts ? Obsolete parts and obsolete + unsupported tools? this isnt doing any favours for the customer....

Modern parts will easy do 400 MHz / 800 Mbps in even the lowest speed grade.

I'm all ears on selecting another parts,

https://www.digikey.com/en/products/detail/efinix-inc/T8Q144I4/11591372
This one from efinix is comparable to the XC6slX9 part from xilinx,  But It has higher price, since I can get the AMD part cheaper in china, also Please note that I prefer TQFP Because of the ease of assembly over BGA, since it would cost less and can be done by hand very easily.

[BrianHG]

https://www.digikey.com/en/products/detail/efinix-inc/T8Q144I4/11591372
This one from efinix is comparable to the XC6slX9 part from xilinx,  But It has higher price, since I can get the AMD part cheaper in china, also Please note that I prefer TQFP Because of the ease of assembly over BGA, since it would cost less and can be done by hand very easily.

You are comparing a real price for the Efinix to a LCSC priced Xilinx.  A brand new version of your Xilinx part at Digikey is actually 53$.   
Read the 2 adjacent posts here regarding LCSC:
https://www.eevblog.com/forum/chat/lcsc-in-china-is-much-cheaper-than-normal-franchised-distributors/msg5604233/#msg5604233

BTW, I find 256pin BGA (0.5mm) easier to hand solder than 144pin TQPF.

[BrianHG]

You want cheap LCSC, here's $4.52:  110kbit ram, 2000lc.
https://www.lcsc.com/product-detail/Programmable-Logic-Device-CPLDs-FPGAs_Intel-Altera-10M02SCE144C8G_C78764.html

No bootprom needed.  It has a built in bootproms with 2 switchable boot-up profiles.
No multi-power-supply.  It can run off a single 3.3v or 2.5v supply.

[glenenglish]

arrghh! there's always an Altera person lurking

Ali, if you are going to hand assemble, surely this means a very low quantity and so FPGA price does not really matter at all.

[BrianHG]

If you could squish you project into this Intel/Altera 5M240ZT100C5N, 100 pin QFP, $2.15 each for 200pcs at  LCSC.

304mb per pin. 

But the 240 logic cells might be a constraint.
Though, you only need to buffer 125 bits + say another 8 bits.

I believe it also has built in flash.
Also, it is more akin to a PLD, not a full fledged FPGA like the MAX10 series.

[BrianHG]

arrghh! there's always an Altera person lurking

Ali, if you are going to hand assemble, surely this means a very low quantity and so FPGA price does not really matter at all.

Read his posts.  Each 'product' requires 200 serial linked acquisition boards, that's two hundred daughter boards, each with the cheap FPGA.  If he saves 5$ in bootprom and FPGA combined, that is a 1k$ savings for each product.  If he sells 10 'products', that's a 10k$ savings.  If he already set his price or already quoted a final amount to his clients, for 10 installations, it is an additional 10k$ in ali_asadzadeh pocket.  If he sells 100 setups, that is an additional 100k$ in his pocket.  At this level, it is worth it to put in the effort to find the cheapest solution.

I'm sure the final processing unit will have some more modern FPGA which is a lot beefier.

Making everything work on a $2.15 FPGA instead of a 7$ one plus it's bootprom price in the OP ali_asadzadeh eyes may make proper business sense.  And if the Altera 5M240ZT100C5N can be made to work, he may thank me for finding it as it will save him at least 1000$ for the first unit with 200 daughter boards.

For prototyping, he may only assemble 3-5 units for testing, but once the PCBs are verified error free, he will have them assembled by the PCB manufacturer.

Even the MAX10 device I listed at $4.52, which can LVDS over 650mb (the 5M240 part maxes out at 304mb) and has a full PLL will still save ali_asadzadeh over 600$ on each setup as he no longer need a boot flash, or VCC core voltage regulator to use that device.  A device which has full real-time operation debug monitoring through the JTAG, PLL and a reasonable blockram unlike the cheaper altera 5M240ZT100C5N where everything need to be programed to the bone.

[technix]

RGMII? Then stick something like RTL8211 and a Magjack and you get gigabit Ethernet. However many devices you have just design an appropriate sized network switching architecture.

[glenenglish]

some other FLASH options (Ali just how many are you going to build )

Brian has given you  some fairly good "PLD like/ small fpga " options for you at low cost.  (Brian, I thought this was one system of 200)

other options
How about IGLOO. they are FLASH. and they have emulated differential signalling ..... and certainly fast enough.
----
If ALi needs cheap, one of these ForgeFLASH Renesas FPGAs might do it , *might* be (just) fast enough.
like 50 cents.
https://www.renesas.com/us/en/document/dst/slg47910-datasheet?r=25546631
24QFN- can be soldered. probably enough I/O - cant remember. and is non volatile.

No LVDS but for 29c you can put LVDS buffers on it like DS90LT1 DS90LV DS90LV018 etc etc series  (SOT23)
---
otherwise T4 or T8 Trion Efinix $1.45 / $1.70  . plenty of logic and 400 Mbps LVDS

[ali_asadzadeh]

You want cheap LCSC, here's $4.52:  110kbit ram, 2000lc.
https://www.lcsc.com/product-detail/Programmable-Logic-Device-CPLDs-FPGAs_Intel-Altera-10M02SCE144C8G_C78764.html

No bootprom needed.  It has a built in bootproms with 2 switchable boot-up profiles.
No multi-power-supply.  It can run off a single 3.3v or 2.5v supply.

Thanks for the feedback, But I think 2K logic elements would be very limiting, Because there are some ADC's with SPI and they have a fair bit of registers that need to be configured, also There are some other Sensors to sample that have a bit of complexity in them, so I think 8K LE is the minimum I would be ok with.

[asmi]

TI also still makes SERDES chips so even if your FPGA can't do high-speed serial you can use these devices to handle transmission/receiving with CDR and everything, and you get a nice parallel interface on both ends.

[BrianHG]

You want cheap LCSC, here's $4.52:  110kbit ram, 2000lc.
https://www.lcsc.com/product-detail/Programmable-Logic-Device-CPLDs-FPGAs_Intel-Altera-10M02SCE144C8G_C78764.html

No bootprom needed.  It has a built in bootproms with 2 switchable boot-up profiles.
No multi-power-supply.  It can run off a single 3.3v or 2.5v supply.

Thanks for the feedback, But I think 2K logic elements would be very limiting, Because there are some ADC's with SPI and they have a fair bit of registers that need to be configured, also There are some other Sensors to sample that have a bit of complexity in them, so I think 8K LE is the minimum I would be ok with.

Setting I2C registers aside which can be stored as a LUT in the 100kbit blockram, such complexity in clocking and shifting an SPI bus to acquire 125bits to be transmitted?  You must also be doing data compression in each FPGA before transmitting the data stream.

BTW, a little secret, when programming a 10M02 FPGA in quartus, just select the 10M04 fpga and upgrade your projects FPGA for free.  Both FPGAs are the same die and selecting the 10M02 is nothing more than a pseudo software on the chips capabilities.

Actually, the same thing be said for the first 2 bottom sizes of most Xilinx and Lattice FPGAs.
You need to google around, but someone has generated a table of many of the available FPGA sizes which are actually identical dies.

Another trick is to search in the datasheets for the raw uncompressed bootprom image file sizes for each FPGA in a set family.  Any 2 or 3 sizes which match the number of bytes, you know the core die is identical.

[BrianHG]

It looks like the XC6SLX4 might have the same core die as the XC6SLX9.  The bitstream has 10 thousand extra bits out of 2 million bits.

Maybe you could save money using the XC6SLX4, try programming it as a XC6SLX9 and see if it works.

[Someone]

It looks like the XC6SLX4 might have the same core die as the XC6SLX9.  The bitstream has 10 thousand extra bits out of 2 million bits.

Maybe you could save money using the XC6SLX4, try programming it as a XC6SLX9 and see if it works.

I was sure I documented that on this forum, but cant seem to find it 

[BrianHG]

It looks like the XC6SLX4 might have the same core die as the XC6SLX9.  The bitstream has 10 thousand extra bits out of 2 million bits.

Maybe you could save money using the XC6SLX4, try programming it as a XC6SLX9 and see if it works.

I was sure I documented that on this forum, but cant seem to find it 

Here: https://www.eevblog.com/forum/fpga/quartus-prime-18-1-cant-fit-design-in-device/msg3179010/#msg3179010

It is a shame since before the pandemic, the Lattice  LFE5U-12F series was around 7$ each for 10 pcs.
It happens to be the same die as the LFE5U-25F, that's a 24k logic cell chip with 1 megabit blockram for 7$ !!!

Today, the LFE5U-12F and LFE5U-25F are 15$, then 20$.  The 12f doubled in price while the 25f went up by around 7$.

[Someone]

It looks like the XC6SLX4 might have the same core die as the XC6SLX9.  The bitstream has 10 thousand extra bits out of 2 million bits.

Maybe you could save money using the XC6SLX4, try programming it as a XC6SLX9 and see if it works.

I was sure I documented that on this forum, but cant seem to find it 

Here: https://www.eevblog.com/forum/fpga/quartus-prime-18-1-cant-fit-design-in-device/msg3179010/#msg3179010

https://www.eevblog.com/forum/microcontrollers/artix-7-only-has-three-different-die-sizes/msg837185/#msg837185
There is it, thanks. Bizarrely it doesn't come up in site searches for keywords and needs a lot of context on google to hit it.

a little bitstream twiddling, and some extensive per device testing (or just faith/dumb luck) gets some extra bang for the buck.

[glenenglish]

just look at Vcc CORE static current.... that tells you what die is what....

Now, just because they're the same die, does not guarentee the whole die works. They do do binning.  (do do?).  Usually the smaller devices in each mask set get released later after the mfr figures out yields, what works, what does not....

@ Ali, any resistance to using Efinix T4, T8 ? they are the highest performance, lowest cost, modern,  and package friendly device that you can choose from.  Just wondering ? I just wonder why you wouldnt consider them when they are very clearly, the best fit (speed, IO, price, tools)  for your project.

[ali_asadzadeh]

Thanks for the feedback

@ Ali, any resistance to using Efinix T4, T8 ? they are the highest performance, lowest cost, modern,  and package friendly device that you can choose from.  Just wondering ? I just wonder why you wouldnt consider them when they are very clearly, the best fit (speed, IO, price, tools)  for your project.

I'm not resisting anything, what prices can I buy them? do you have a source with good prices? I can get XC6SLX9 around 6$ from my Chinese supplier

[BrianHG]

https://www.questcomp.com/part/4/t4f81c2x/435178692?utm_source=findchips&utm_medium=industry-cpc&utm_term=t4f81c2x&utm_content=standardpricing&utm_campaign=aktype0

$3.60 x200

https://www.digikey.com/en/products/detail/efinix-inc/T4F81I2X/16162570

$3.61 x1500  ***industrial temp range version, -40°C ~ 100°C (TJ)

[ali_asadzadeh]

https://www.questcomp.com/part/4/t4f81c2x/435178692?utm_source=findchips&utm_medium=industry-cpc&utm_term=t4f81c2x&utm_content=standardpricing&utm_campaign=aktype0

$3.60 x200

https://www.digikey.com/en/products/detail/efinix-inc/T4F81I2X/16162570

$3.61 x1500  ***industrial temp range version, -40°C ~ 100°C (TJ)

Thanks for the update, what about the software? is it free too? what about the programming tool, does Generic FT2232 work as well?

[BrianHG]

If you do not need the IO count and only need 4klc, this one is a $1.70 in quantity:
https://www.digikey.com/en/products/detail/efinix-inc/T4F49C2/11591374
T4F49I versions exist.

The effinix T4 series only goes up to 400mb in sdr mode only.

The effinix T8 series supports DDR on their IOs for their 144pin qfp, up to 800mbps:
https://www.digikey.com/en/products/detail/efinix-inc/T8Q144C4/11591363
T8Q144I versions exist.
Contact Digikey for quantity pricing...

[glenenglish]

Ali
contact the maufacturers representative, you'll always get half to one quarter  the price of digikey....
T4 is too cut down, suggest T8 or T13 or  T20
https://www.efinixinc.com/products-trion.html

QFP100 is available with on chip FLASH in T13, T20 size (you'll pay something for the flash)
otherwise QFP144  T8/T20
I would be using a T13 or T20  in a 0.65mm 169 ball BGA. easy.

go read the site.