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Altera_Forum's avatar
Altera_Forum
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19 years ago

My PCB design for Cyclone II ep2c20F484;ep2c35F484

I am begginer ir FPGA and the problem I have is with these development bords is that they are very expensive! cheapest bord I found with cyclone II ep2c20 FPGA is firefly bord with cost 350$ and its too expensive and second problem is that these FBGA chips is olmost inposible solder by hands soldering wires to pins.

Only solution is to make PCB and there is third problem that this PCB trace width is wery small 8mils (0.2mm) and ALTERA recomended trace width for PCB is 5mils (0.12mm) and drill hole 8mils (0.2mm) so not all PCB manufacturers can make these PCB and 4 leyer PCB is almost 2.5 times expensiver than 2 leyer PCB.

And I calculated that for me and my frend buying 2bords will cost 700$ and making my own PCB will be mutch cheaper about 300$ for PCB and 100$ for FPGA and ather components.

here is a picture of unfinished PCB

http://theonlyway.net/eoz/upload/attachment.php?attachmentid=678&d=1153642561

if you don't see the picture go to this link http://theonlyway.net/eoz/upload/attachmen...78&d=1153642561 (http://theonlyway.net/eoz/upload/attachment.php?attachmentid=678&d=1153642561) (it is a forum Where I posted the picture)

There will be availible all IO pins and special purpose pins like those for programming and on bord JTAG conection, 16Mb configuration FLASH, and Power suply circruit for core 1.2V and for IO pins 3.3V

on this bord will be for 3 cyclone devices EP2C20F484;EP2C35F484;EP2C50F484

In 3 PCB leyers I routed out 90 pins on one side so totaly In 3 leyers it is posible to route out 360 pins http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif of FBGA484 package and 4th leyer will be GND and VCC

I am designing this PCB about 2 weaks and previously I designed FBGA 256 package in 2 leyers for EP2C20F256C8 device.

Picture of almost complete 2 leyer PCB designe for EP2C20F256C8 device.

http://theonlyway.net/eoz/upload/attachment.php?attachmentid=676&d=1153473055

if dont see image go to

http://theonlyway.net/eoz/upload/attachmen...76&d=1153473055 (http://theonlyway.net/eoz/upload/attachment.php?attachmentid=676&d=1153473055)

Wen I will finish my designe I will post the picture.

So what you think about my PCB designe is there somthing I missed ?

I plan to develop CNC motion controller to syncronise 4 stepper motors and 1 AC motor with Quadrature encoders, and I olready developed code for motor sinhronization for ATMEL microcontroller Mega128 but it don&#39;t work in device and there is too small periperals like PWM generators, 16bit timers, and Input Capture units for all operations thats why I plan to lern FPGA becose ther is no limits you can make so mutch periperals as you need http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif .

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  • Altera_Forum's avatar
    Altera_Forum
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    19 years ago

    Can VCC INT be 1.8V insed of 1.2V ??

    I ask becouse I found one DC-DC 2.5Mhz step down regulator SC2440 SEMTECH which I can buy in digikey (all ather Mhz range regulator as don&#39;t company person I can&#39;t buy in small Quantitys (4)) for 3.7$ and it has 2 separet outputs (eatch 2A) with separet voltage levels and problem is that there in datasheet is few example designs ( 1.8v 2A and 3.3V 2A output setings) and there is no 1.2V 2A design and i don&#39;t know these ather compnent values (there is calculation example but I don&#39;t want to get in to it so If it is posible to use 1.8V in VCC INT it would be mutch easyer without calculation.

    I looked in Cyclone II device family data sheet and there was sayed that VCC INT must be 1.2V but in other table ( Table 5-1.Device absolute maximmum ratings, page 103) was that VCC INT max can be 1.8V)

    So how it is can I suply 1.8V in VCC INT ???

    I think that this SC2440 is cheapest DC-DC that could be found with 2 voltages and 2A load rating.
  • Altera_Forum's avatar
    Altera_Forum
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    19 years ago

    All previous 3 weaks I serched distibutor for Actel Fusion afs600 device, but I could&#39;t finde (they all sell in big Quantitys >120) So I devicded to return to cyclone II and I found that Dannaher motion for they SERVO motor systems used spartan 3 XC3S400 and it could be compared to EP2C8 so I fink I will switch to this EP2C8Q208C and will make 4 layer cheap PCB and there will be no soldering problem using PQFP 208 package.

    I think this is my final decision and it is mor realistic than making PCB for BGA package for EP2C20 or switching to ACtel Fusion afs600 device which I can&#39;t buy ofcourse I can buy Fusion starterkit but it is expensive 500$. And if I will make application on this device then it will have no future becose I can&#39;t buy this device, compared to cyclone II which is availible in digikey.com and ather onlineshops.

    my parts for cyclone II bord will cost about 45$ +VAT and shiping http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif for now it is cheapest solution. and PCB I will mak in local PCBHouse and will solder by my self.
  • Altera_Forum's avatar
    Altera_Forum
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    19 years ago

    I just soldered my FPGA bord here is picture link:

    http://www.cnczone.com/forums/attachment.p...42&d=1169640509 (http://www.cnczone.com/forums/attachment.php?attachmentid=30242&d=1169640509)

    I checked power supply and it is working good at 250Khz now I will solder buteblaster and will check if FPGA is working http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif

    Tomorow I will get my Cyclone II starter.kit for 150$ http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif I ordered it as Optional bord for code debugging and testing becose it has lot of switches and leds http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/cool.gif
  • Altera_Forum's avatar
    Altera_Forum
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    19 years ago

    A few capacitors will probably not be enough.

    Altera recommends a capacitor for each power pin end especial care for PLL power supply. We had a lot of problems with improper power decoupling on Cyclone II chips in TQFP package. Check decoupling instructions in the high speed design document for Stratix chips.

    On our first design the processor crashed while accessing to the external SRAM, bot worked correctly from the internal memory, the problem was ground bouncing due to toggling output signals. This problem can be alleviated by lowering the current strength of Cyclone output pins.

    After we improved the decoupling we got crashes due to some signals disturbing a PLL. So we are creating a third redesign.

    IzI
  • Altera_Forum's avatar
    Altera_Forum
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    19 years ago

    maby You did&#39;t noticed but there is place for 23 (SMD 0805) decoupling caps for each power pin I think it could be enough or I can try to solder 2 caps on one place so I will totaly have 46 caps how about that ??

    for 3,3V I curently have soldered one big 220uF cap.

    I am thinking of 0,2uf caps is this value corect.

    Here is osciloscope mesurement picture where I mesured 3,3v powersuply performance

    blue line is probe from DC-DC regulator output and red line is probe from 220uF cap outut and load is one Led (20ma)+ 16Mhz oscilator and empty FPGA. soan i will solder EPCS16 configuration flash.

    http://theonlyway.net/eoz/upload/attachmen...77&d=1169634985 (http://theonlyway.net/eoz/upload/attachment.php?attachmentid=2077&d=1169634985)

    I think when I will solder these 23 0,2uf caps this voltage riple will be mutch smother http://forum.niosforum.com/work2/style_emoticons/<#EMO_DIR#>/smile.gif