RAM on the UDOO Quad board

Discussion in 'General Discussion' started by shaunakrs, Dec 2, 2014.

  1. shaunakrs

    shaunakrs New Member

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    Hi,
    I was going through the UDOO Quad Rev D schematic when I noticed that the RAM chips that have been used are 256Mb x 16 = 4096Mb or 512MB. Four such chips have been used, however, the UDOO is still configured to use only 1GB of RAM.
    Please can you let me know if there is a technical reason this has been done? I tried messing around with the U-boot and the kernel and got the board to boot; the however, crashes if I run heavy apps like the web browser and continually load heavy web pages.

    Thanks very much.

    Regards,
    Shaunak
     
  2. gionji

    gionji Member

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    Hi,

    UDOO use 4 Micron MT41J256M16RE-15E RAM modules (2Gbit for each module) for a total of 1GByte. The clock frequency is 400mhz for UDOO dual and 528mhz for UDOO quad.

    Regards
     
  3. shaunakrs

    shaunakrs New Member

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    Hi gionji,

    Thank you for your reply. I googled MT41J256M16RE-15E and the datasheet mentions that this is a 4Gbit DDR3 module. Please can you confirm if the module populated on the board is a 2Gbit one? I have attached the datasheet I found herewith.

    Thanks very much.

    Regards,
    Shaunak
     
  4. gionji

    gionji Member

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    Confirmed ;)
    But im going immediately to check if the RAM module code is correct.

    I-ll notify it immediately!

    Thanks
     
  5. gionji

    gionji Member

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    I'm sorry,

    this is the correct code: MT41K128M16JT-125
     
  6. shaunakrs

    shaunakrs New Member

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    Hi gionji,

    Sorry for my late reply. I was away for sometime.
    Thank you for confirming. Would it be possible for you to inform your engineers to modify the Rev D schematic and rename the RAM module to MT41K128M16JT-125 and upload the latest schematic?

    Regards,
    Shaunak
     
  7. sirrab

    sirrab UDOOer

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    Sure would be nice if UDOO had 2GB of memory!
     
  8. LDighera

    LDighera UDOOer

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  9. shaunak_s

    shaunak_s New Member

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    Hi LDighera,

    The DDR3 part number you have provided has a max density of 2Gbits. That means each module packs a maximum of (128M x 16) = 2048Mbits = 2048 / 8 = 256MB. So you would need 8 such modules using CS0 and CS1 on the iMX6 to make 2GB. An alternate is to use 4 x 4Gbit modules on CS0 (similar to the configuration currently used on the UDOO board).

    Regards,
    Shaunak
     
  10. fetcher

    fetcher Member

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    I did the piggybacked-memory thing too back in DIP-chip days. Fun times. This unfortunately won't work on a Udoo, because the DRAM ICs are ball-grid-array types, with no accessible pins. All connections to the board are instead made through solder-bumps on the bottom. It's hard to see the Udoo's memory chips without removing its heatsink, but you might have noticed the same IC style on newer PC DIMM modules. Compared to more conventional chips with side-facing pins, I think this type of package has lower lead inductance, allowing for faster bus speeds, but it isn't at all friendly to homebrew mods.

    The i.MX6 chip is BGA also, so there's no practical way to access unused pins that aren't brought out, like the DRAM CS1 signal Shaunak mentioned. Even if I had access to serious surface-mount rework equipment (and steadier hands!), I wouldn't want to try attaching extra wires to the bottom of a BGA package.
     
  11. LDighera

    LDighera UDOOer

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    Hello Shaunak,

    Thank you for your interest in this issue. You are correct, of course, I referenced the incorrect part number.

    In researching appropriate replacement 2-GB SDRAM chips that may possibly be employed to replace the 1-GB MT41K128M16JT-125 chips which require 1.35VDC, I have found a few that may work:

    MT41K256M16HA-125 IT:E TR https://parts.arrow.com/item/detail/micron-technology/mt41k256m16ha-125itetr#pzER

    MT41K256M16HA-125 IT:E TR https://parts.arrow.com/item/detail/micron-technology/mt41k256m16ha-125itetr#JJ2y

    MT41K256M16HA-125:E TR https://parts.arrow.com/item/detail/micron-technology/mt41k256m16ha-125etr#FRcR

    A cursory look at the parameters of these chips indicates that they are generally physically 1 mm wider than the MT41K128M16JT-125M:K chip, require an additional address bit (18 instead of 17), and require twice the current of the original MT41K128M16JT-125 RAM chips. So, if the address buss is able to provide the additional bit, and the power supply is able to handle the additional 1 amp of current draw, it may be possible to swap one of these three for the original RAM.

    Indeed, from page 5 of the Udoo quad schematic diagram http://udoo.org/download/files/schematics/UDOO_REV_D_schematics.pdf it does appear that the Udoo quad was designed to use 4-GB, 1.5 VDC DRAM chips as the part number indicated there is: MT41J256M16RE-15E. However that part requires 1.5VDC not 1.3, so the issue is a bit murky. I'm not able to see the part number of the RAM chips installed under the heat-sink, so It's difficult to be sure exactly what is required. But if the schematic is correct, and the Udoo quad was actually engineered for 4-GB RAM chips, increasing the memory to 2-GB may be as simple as replacing the installed MT41K128M16JT-125M:K chips with those called out on the schematic: MT41J256M16RE-15E https://parts.arrow.com/item/search...chnology;micron-technology;micron-technology;.

    From the information here https://parts.arrow.com/item/detail/micron-technology/mt41j256m16re15ed#2ppJ it appears that the MT41J256M16RE-15E called out on the schematic is obsolete; this may be the reason for the change to the MT41K128M16JT-125 chips. There's a cross reference and list of newer parts on that page that may lead to a 4-GB part that is suitable to upgrade the Udoo quad to 2-GB of RAM. I'm unable to use the Udoo quad PCB top layout here http://udoo.org/download/files/schematics/udoo_top_rev_d.pdf to provide much of a clue.

    It sure would be helpful to get some guidance from the Udoo design team on this issue. :?

    Best regards,
    Larry
     
  12. sirrab

    sirrab UDOOer

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    All 4 memory chips have to be replaced. If you notice, the i.MX6 processor has a 64 bit data bus, in the schematic. And I also see A0-A15 address lines, plus 3 Bank address lines. Seems to me, that is effectively 19 address lines.
     
  13. LDighera

    LDighera UDOOer

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    Being that the Udoo quad was originally designed with 2 GB of RAM (as shown in the schematic diagram) like the CuBox-i4Pro http://www.solid-run.com/product/cubox-i4pro/, I would expect that there would be sufficient address lines. So that would seem to leave two questions remaining:

    1. Is the power supply adequate to provide the additional 1 amp of current at 1.35 VDC or 1.5 VDC required by the 4 GB RAM chips?

    2. Which RAM chip is the most appropriate one to replace the originals?

    If the dimensions of the new replacement RAM chips's ball pattern are compatible with those on the Udoo quad's PCB, I would expect the actual unsoldering and resoldering to be fairly straightforward, if the proper equipment is available. Perhaps something like these: http://www.circuitspecialists.com/hot-air-station.

    So, what's involved in removing the Udoo quad's heat sink? It would seem that gionji may be able to provide some guidance there.
     
  14. sirrab

    sirrab UDOOer

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    Removing them is relatively easy with hot air. Getting new ones back on, is way more difficult and expensive.
     
  15. LDighera

    LDighera UDOOer

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    That's interesting information. I'd like to know more about the underling data that leads you to those conclusions. Why is soldering the new ones going to be expensive? It would seem, that once the original chips are removed, installing the replacement RAM chips would be a matter of removing the residual solder from the PC board, positioning the new chips correctly, and heating them (with hot air?) to reflow the solder and bond them to the old PCB pads. Am I missing something?

    I've got a little hardware experience, but it is primarily with earlier technology: http://kj6yvt.com/speak&spell_Feb1983.PDF. That said, I have been successful in hand-wiring/soldering SMD devices recently, so I'm game to make the attempt to replace the RAM chips...
     
  16. sirrab

    sirrab UDOOer

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    The hard part is getting the new chips lined up correctly onto the PCB pads. The chip covers them. The machine that does it has fancy optics, that let you "see" the pads and solder balls, at the same time. It also has heaters below and above the PCB, a mechanism to hold the chip before placement, and controls to move the chip around for alignment with the PCB pads. It costs upwards of $30,000 US dollars. Where I work has one. You have to remember, the solder balls are about 1 mm apart from each other. Once the part is placed, there is another machine that uses X-rays to confirm the solder balls have "flowed" properly onto the PCB pads. My work doesn't have one of these machines. You are trying to make it sound easy, but, I assure you, it is not. If it were, I would have already replaced my chips for 2GB of memory!
     
  17. sirrab

    sirrab UDOOer

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    OMG! Solder b*lls gets censored here!
     
  18. shaunak_s

    shaunak_s New Member

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    Hi Larry,

    Your analysis is spot on. The address lines should not be a problem. iMX6 is designed to support up to 4GB of RAM. Make sure you get the voltages right. The UDOO board has a 1.5V DDR3 supply with a REF of 0.75V. The reference is required for proper termination of the lines (SSTL). Using a +1.35V DDR3L chip may need you to tweak the power supply design to get +1.35V.
    I agree with sirrab on the rework though. It's going to be a hell of a job only realizable in production houses with the correct equipment. BGA chip placement is another animal. All in all its going to be difficult to accomplish without the right equipment. You could try and get in touch with small production houses that support board rework and get a better price on the job.

    Thanks very much.

    Regards,
    Shaunak
     
  19. LDighera

    LDighera UDOOer

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    What is the part number of the chips you would have used? :D

    Thank you for the information. I understand that alignment of the chips' solder balls with the PCB pads can be an issue due to their being obscured beneath the chips. And there is the issue of getting the chips and PCB solder pads hot enough to melt the solder without overheating the chips. But I would be willing to give it a try.
     
  20. LDighera

    LDighera UDOOer

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    Did you mean 4GB RAM chips for a total of 2GB of RAM?
    The way I read the schematic, it appears the RAM chips are fed with 1.5VDC. However, gionji assures us that the Udoo quad RAM chips are MT41K128M16JT-125 in his message earlier in this thread: http://www.udoo.org/forum/ram-the-udoo-quad-board-t1998.html#p11170. So are you saying that 1.5VDC chips can be used in place of the current 1.35VDC chips?
    I understand. Thanks for your input.

    I did contact the firm that ostensibly designed the Udoo quad, SECO s.r.l., regarding increasing the RAM to 2-GB. Here is the response I received:
    Code:
    Dear Mr Dighera,
    
    you are right: UDOO was designed with 2GB RAM upgradability in mind. 
    This is something that we will probably do in the future, but there is 
    no fixed schedule yet.
    
    Best regards
    --
    *Alessandro Santini*
    
    Area Manager
    Sales Dept.
    
    *SECO s.r.l.*
    Via Calamandrei, 91
    52100 Arezzo - ITALY
    
    Mob. +39 348 3580476
    Ph. +39 0575 26 979
    Fax +39 0575 350 210
    Skype: alessandro.santini70
    
    www.seco.com <http://www.seco.com/>
    
    ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
    
    Il 16/12/2014 22:38, Larry Dighera ha scritto:
    > Dear Sirs:
    >
    > Are you able to provide information on upgrading the 1-GB of RAM to 2-GB for
    > the Udoo quad?  It appears from the schematic diagram that it was originally
    > engineered for 2-GB.
    >
    > Specifically:
    >
    >    1.  Are all the required traces on the Rev D PCB?
    >    2.  Is the power supply adequate to power the additional 1 amp of current?
    >    3.  What chips currently available would be appropriate to replace the
    > existing?
    >
    >    4.  Other considerations?
    >    5.  Are you equipped to implement the upgrade?
    >
    > Thank you for any assistance you may be able to provide.
    >
    > Best regards,
    > Larry Dighera
    >
    Thank you for the thoughtful information you've provided.

    I'd sure like to see one of the Udoo engineering team provide a 4GB RAM chip part number to replace the current 2GB chips.
     

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