128MB SDRAM v2.9

[leosmendes]

In the topic "MiSTer updates and changelog" @Sorgelig say

Hardware - New SDRAM v2.9:

Could you post pictures of the new project? will it be possible to change a v2.5 to v2.9 project?

[Xbytez]

3D render of the rear of the updated SDRAM memory module.

1.jpg (102.47 KiB) Viewed 22772 times

[Sectorseven]

Does that new pin header have to be done in a reflow oven? Don't see how you could fit a soldering iron in there.

[PhantombrainM]

Is this to be sold or still R&D ?

[invzim]

Looks like a routing error on this version, pin 1&3 are VDD supply pins, but share a capacitor. Pin 37 is a signal pin tied to VDD, but has a capacitor which probably should be on one of the supply pins.

[aberu]

Does that new pin header have to be done in a reflow oven? Don't see how you could fit a soldering iron in there.

You probably could with a thin enough tip. Elongated Shape J or Shape SB T12 tips could do this if they are thin enough.

[dshadoff]

It would normally be done in a reflow oven or with a hot air rework station. Very fast. Just perhaps not as mechanically strong.

[aberu]

Preferable design for builders overall, because trimming the through hole headers to the right height wasn't that easy. Baking on some solder paste is easier, and most of the resellers already use reflow all of the time anyways.

My main problem so far is... I have no experience with that header and can't easily find it online! Was just curious to build up a BOM and store it away for awhile, and everything is sold out!

EDIT: Nvm spoke too soon!

https://www.aliexpress.com/i/4000318372 ... 07c8704-17

[Newsdee]

Would this design be more compatible with PCB fabrication shops? If so, it should drive down cost...

[C-R-T]

The LDO used is in a nonstandard package. The LM1117 does not come in SOT89. Looking for this I only find Chinese brands. It’s not the first time I see the Mister project using these kinds of low quality/fake components.

[aberu]

The LDO used is in a nonstandard package. The LM1117 does not come in SOT89. Looking for this I only find Chinese brands. It’s not the first time I see the Mister project using these kinds of low quality/fake components.

huh? HTC Korea is a Chinese Brand?

https://lcsc.com/product-detail/Dropout ... 26021.html

https://lcsc.com/product-detail/Dropout ... 26020.html

[C-R-T]

Sorry, I should have said low quality brand. Pretty much anything you can find on LCSC.

[aberu]

Just because something isn't Texas Instruments doesn't make it bad though.

I get what you are saying, but the reaction was pretty out of proportion lol

Also...

https://careers.ti.com/locations/#asia

TI doesn't mean it's not made in China.

[invzim]

We need a part number/source for the 40pin RA connector. I've been previously searching for something like that, but couldn't find it through the 'normal' channels.

[MickGyver]

Thanks for the new version, I have to build a few for my MiSTers!

What is the correct layer stackup of the PCB for controlled impedance? JLCPCB supports two stackups, JLC7628 with 0.2mm prepreg and JLC2313 with 0.1mm prepreg, which one to use?

Also what capacitor configuration is recommended for this version?

[bnz99]

I'd be interested in answers from someone knowledgable in electronics to MickGyvers questions as well. My electronics knowledge is not very deep

From what I see, there are two new ones in the top row which used to be 10uF, 0.1uF - 10uF, 0.1uF for the 2.5 module.
Given that my understanding is that they are bypass capacitors, I'd guess that this should probably either be 10uF, 1uF, 0.1uF or 10uF, 0.1uF, 0.1uF for each chip or maybe even something like 10uF, 0.1uF, 100nF. Not sure what is better here.

The C15 one probably should be 10uF as stated in the schematic as it matches the capacitance stated in the data sheet of LM1117 for the input.

About the layer stackup, my guess would be that uncontrolled is fine. From what I have read, controlled impedances should normally be marked as such in the schematic.

Again, I have little idea what I'm talking about and would love to hear some opinions from someone who knows better, I just want to get the discussion going

[Newsdee]

Is anybody selling these new versions yet?

[MickGyver]

I'd be interested in answers from someone knowledgable in electronics to MickGyvers questions as well. My electronics knowledge is not very deep

From what I see, there are two new ones in the top row which used to be 10uF, 0.1uF - 10uF, 0.1uF for the 2.5 module.
Given that my understanding is that they are bypass capacitors, I'd guess that this should probably either be 10uF, 1uF, 0.1uF or 10uF, 0.1uF, 0.1uF for each chip or maybe even something like 10uF, 0.1uF, 100nF. Not sure what is better here.

The C15 one probably should be 10uF as stated in the schematic as it matches the capacitance stated in the data sheet of LM1117 for the input.

About the layer stackup, my guess would be that uncontrolled is fine. From what I have read, controlled impedances should normally be marked as such in the schematic.

Again, I have little idea what I'm talking about and would love to hear some opinions from someone who knows better, I just want to get the discussion going

From what I have figured out, the layer stackup should be JLC7628 (0.2mm prepreg), at least that seem to have been the one for the older version. C15=10µF and I will try this for the capacitors when I get the PCBs (1µf for the "new" caps):

Code: Select all

top row: 10µf, 0.1µf, 1µf, 10µf, 0.1µf, 1µf
bottom row: 10uf, 1µf, 1µf, 10µf, 10µf, 1µf, 1µf, 10µf

[dmckean]

Is anybody selling these new versions yet?

I know that Ultimatemister is.

[Newsdee]

I know that Ultimatemister is.

It's listed as 2.9, but the picture looks different. Has anybody ordered it yet?

[warham]

I know that Ultimatemister is.

It's listed as 2.9, but the picture looks different. Has anybody ordered it yet?

looks modified to still use a thru hole header

[Fuzzball]

Please excuse my ignorance, but having only just bought a v2.5 128Mb SDRAM, why is a new revision necessary? In layman's terms, Is there something wrong with the 2.5?

[hiddenbyleaves]

Please excuse my ignorance, but having only just bought a v2.5 128Mb SDRAM, why is a new revision necessary? In layman's terms, Is there something wrong with the 2.5?

I think they are prone to being faulty. Problems were discovered when Jotego released his CPS1.5 or CPS2 beta and around 20% of users had problems if I remember correctly.

[robinsonb5]

looks modified to still use a thru hole header

I think it's just that they're still using photos of the 2.5 module.

Please excuse my ignorance, but having only just bought a v2.5 128Mb SDRAM, why is a new revision necessary? In layman's terms, Is there something wrong with the 2.5?

For most people the 2.5 module works fine. Some people have had issues with the 2.5 module and certain cores which make heavier demands of the SDRAM (mostly Jotego's CPS cores). These have been attributed to insufficient power conditioning and suspect signal integrity with the 2.5 module, hence the redesign. Nonetheless the 2.5 module works fine for an awful lot of people, so unless you encounter problems with yours there's no need to worry about it.
(Even with the redesign, the FPGA and SDRAM module are still separated by a 40-pin header, and the DE10-nano half of it is still through-hole - so the signal path is still the high-speed-electronics equivalent of a dirt track; there are just somewhat fewer potholes than before.)

[pbsk8]

Please excuse my ignorance, but having only just bought a v2.5 128Mb SDRAM, why is a new revision necessary? In layman's terms, Is there something wrong with the 2.5?

if you run memtest by jotego and everything runs fine, like it did for me, a new version is not necessary for you

[antoniovillena]

There is a better test also by Jotego

https://github.com/antoniovillena/MiSTe ... p?raw=true

If your SDRAM module passes all 8 rbf you won't have future problems with your module

[rickdangerous]

I know that Ultimatemister is.

It's listed as 2.9, but the picture looks different. Has anybody ordered it yet?

looks modified to still use a thru hole header

Of course not. We use smd design for some months. I don't use the TH header anymore. Iv'e been testing this new rams for months.

I will do stock photos and update site photos soon, sorry no time yet.

[eightbitminiboss]

There is a better test also by Jotego

https://github.com/antoniovillena/MiSTe ... p?raw=true

If your SDRAM module passes all 8 rbf you won't have future problems with your module

Could I get an explanation of how to run these tests? Is it just running each individual core and run the ghouls rom and if it passes the boot up tests, it's considered a pass?

[bnz99]

Has anyone here already tested a specific capacitor setup for a longer period? I'll have all my parts ready next week to build one of those new 2.9 boards.

[antoniovillena]

There is a better test also by Jotego

https://github.com/antoniovillena/MiSTe ... p?raw=true

If your SDRAM module passes all 8 rbf you won't have future problems with your module

Could I get an explanation of how to run these tests? Is it just running each individual core and run the ghouls rom and if it passes the boot up tests, it's considered a pass?

Yes. If passes all cores with ok on boot up tests the memory is ok