Talk:LaFonera Hardware 32MB SDRAM MOD

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Revision as of 21:55, 17 July 2007 by Pinkevin (Talk | contribs)
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Is it possible to replace the m25p64 flash chip with the m25p128 to double the flash space? Daemondust 04:53, 23 Apr 2007 (CEST)

Which type of SDRAM

Hi to all. The original SDRAM chip on the Fonera is a hynix HY57V281620ETP-H which features: 128 Mbit organized as 4 banks x 2 Mbit x 16, 133 MHz An ideal chip needed for the 32MB upgrade may be the hynix HY57V561620ETP-H which is: 256 Mbit organized as 4 banks x 4 Mbit x 16, 133 MHz. Unfortunately is difficult to buy single chips (or small amounts), so we prefer to use PC133 SDRAM modules (like a 512MB PC133 DIMM module - double sided, 8 chips per side - or 256MB PC133 SODIMM module - double sided, 4 chips per side - ). The question is that not all chips from these modules are organized as 4 banks x 4 Mbit x 16. For example, I saw a 512MB PC133 DIMM module with 16 Micron Technology MT48LC32M8A2BB-75 which is organized as 4 banks x 8 Mbit x 8, 133 MHz. Is it possible to do a Fonera RAM upgrade with this chip? (in other words: does the different organization of the same memory size make the difference?)

Piggy packing 32MB

Hi,

I too thought about extending the Fonera's RAM.
However, I would have gone a different route. Since it is quite hard to desolder SMD and you can potentially damage the PCB, I would have tried something like:

- Desoldering or cutting CS# on the original module (in such a way that a wire can still be attached to it)
- Piggy packing the 32MB module on top of it, i.e. solder each pin except CS# to the lower chip.
- pull high the lower chip's CS#
- connect the upper chip's CS# to the PCB

Only thing is I'm not sure that pulling CS# high will actually tri-state the chip's outputs. Maybe you also / instead have to pull CKE low.

just my $0.02

List of working memory chips

Although I doubt many people have or will complete this modification, I think we should compile a list of working replacements for the original memory chip.

I can hereby confirm that the Micron MT48LC16M16A2-75 (:D) works flawlessly.
But, for some reason the modified OpenWRT distribution that the Fonera is shipped with only shows 16 MB. DD-WRT on the other hand shows it all.

- Pinkevin