Increasing NGW100 SDRAM

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Has anyone tried replaceing the SDRAM chip on NGW100 with a bigger one? The schematic says it should be possable.

I found that MT48LC32M16A2 is pin compatable with the MT48LC16MI6A2 but is 64MB in size.

I guess i have to rebuild uboot to recognize the bigger RAM?

Has anyone tried this? and if so. what chip did you use?

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An eye over those chips says you're right, the 64MB should work fine. And you guess right, all you'll need to change is the SDRAM params in uboot.

Many people (myself included) have done this with no worries on an STK1000, I haven't heard of anyone doing it with an NGW100.

Let us know how you go.

-S.

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Hi squidgit,

you wrote

Quote:
...
Many people (myself included) have done this with no worries on an STK1000, ...

can you please tell me what chip you've used ?
Could the IS42S32800B be a choice ?

regards

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I'm also interested in increasing the SDRAM on the STK1000, so I'd love to hear the part numbers of chips people have used with success.

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Just the 16MB version of the 8MB chip that's on there. The 16MB version has pn 48LC4M32B2. There is/was also a 32MB version of this SDRAM chip which is discontinued but was still available on digikey last time I checked.

If you have an eye over the STK1000 schematics you'll notice that they actually have the symbol and footprint for the 16MB version, they just have a note which says "only fit the 8MB one".

Pretty much though the SDRAM footprints are a standard kind of a thing across manufacturers, you should find that any similarish kind of chip will work. If in doubt you can post and ask here, but all you really need to check is the footprint. The EBI only runs at ~75MHz, you'll be hard pressed to find SDRAM which can't take this. All the other parameters are configurable from the software side (uboot).

-S.

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ropa wrote:
Could the IS42S32800B be a choice ?
And having said all that I still didn't answer the second bit of your question, sorry :)

Yeah that chippy looks good. Correct bus width, plenty fast enough etc. I didn't check the pinout meticulously, you should probably do that, but I don't forsee a problem at all :)

-S.

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Thanks for the additional information, appreciated!

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Thanks a lot my master :D
Hopefully the board will survive :!:
I'll keep you informed.

Regards

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ropa wrote:
Thanks a lot my master :D
Go well young Padawan ;)

-S.

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Hi squidgit,

the IS42S32800B is working with the stk1000.

    U-Boot 1.1.4-at0 (Jun 27 2007 - 16:15:25)

    U-Boot code: 00000000 -> 000153ef data: 24000000 -> 24003e10
    SDRAM: 16 MB at address 0x10000000
    Testing SDRAM...OK
    malloc: Using memory from 0x10f80000 to 0x11000000
    Flash: 8 MB at address 0x00000000
    .
    .

It's not tested extensive, but looks good!

Many thanks for your help again.

Regards

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I also need to upgrade two boards, what's the process? Should I just pick the chips (this I can manage) then get the job done? Our soldering kit is not up to much.......;-)

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The process is to pop the old chip off the board, sodder the new one on and rebuild uboot with the updated settings for number of rows/columns/timing etc.

Whereas there's a fair bit of room to manoeuvre on the STK1000, you'll need to be a bit more careful on the NGW. If your soldering kit isn't up to much you might want to scout someone with some better gear, if you pull a pad on a board like that you ain't gonna be happy :)

-S.

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Use the Flux! Without it, all hope is lost.

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I guess I'm more concerned about HOW to lift the chip, my soldering iron has a big tip...honest!

So it's a surface mount component, I should take it somewhere........

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Oh yes, it's very much surface mount. The best way I've found to remove these is to get soldering tweezers (or 2 irons if you've got good dexterity) with very wide tips, pile on the solder and slide the tweezers up and down each side until all the pins are simultaneously molten, you can squeeze the tweezers and lift the chip off. Of course this method often leaves you with lots of solder floating around the board so you have to be careful and go and mop up with some solder wick or something.

But yes, if you've just got the one iron which has a fat tip I would suggest taking it to a clever bloke with steady hands and the right tools for the job.

-S.

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Another method is to use a hot air and tweezers. Blow on the pads on boths sides and when the solder starts flowing lift the chip of the board or push it off the pads. The downside to this is its easy to blow the smaller chips off

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I made myself a QFP desoldering tool a while ago, simple 15W heating element in a square shape that fits over a pair of wide tweezers. All I do is get a hold of the chip from the corner, then lower the heating element (around 4/16" in diam, just sits on all the pins simultaneously) and gently pull the chip off. Works everytime..

Only problem is you need a different tool for every footprint... :)

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If you don't want to salvage the old chip, you can carefully cut the pins with a pair of really fine side cutters, discard the body then remove the pins with a moderate sized iron and solder wick. This method applies minimal force on the pads and the minimum amount of heat to the board.
You'll end up with nice clean pads for fitting the new chip.
Of course, if you really want to keep the old chip this method won't suit at all.

C