128MB SDRAM v2.9

leosmendes
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128MB SDRAM v2.9

Unread post by 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?
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Re: 128MB SDRAM v2.9

Unread post by Xbytez »

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

1.jpg
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Sectorseven
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Re: 128MB SDRAM v2.9

Unread post by 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
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Re: 128MB SDRAM v2.9

Unread post by PhantombrainM »

Is this to be sold or still R&D ?
invzim
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Re: 128MB SDRAM v2.9

Unread post by 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.
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Re: 128MB SDRAM v2.9

Unread post by aberu »

Sectorseven wrote: Wed Apr 21, 2021 4:39 pm 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.
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Re: 128MB SDRAM v2.9

Unread post by 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.
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aberu
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Re: 128MB SDRAM v2.9

Unread post by 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! :P 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
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Newsdee
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Re: 128MB SDRAM v2.9

Unread post by Newsdee »

Would this design be more compatible with PCB fabrication shops? If so, it should drive down cost...
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Re: 128MB SDRAM v2.9

Unread post by 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.
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Re: 128MB SDRAM v2.9

Unread post by aberu »

C-R-T wrote: Thu Apr 22, 2021 4:52 am 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
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Re: 128MB SDRAM v2.9

Unread post by C-R-T »

Sorry, I should have said low quality brand. Pretty much anything you can find on LCSC.
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Re: 128MB SDRAM v2.9

Unread post by 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.
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Re: 128MB SDRAM v2.9

Unread post by 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.
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MickGyver
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Re: 128MB SDRAM v2.9

Unread post by 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
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Re: 128MB SDRAM v2.9

Unread post by 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 :-)
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Re: 128MB SDRAM v2.9

Unread post by Newsdee »

Is anybody selling these new versions yet?
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MickGyver
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Re: 128MB SDRAM v2.9

Unread post by MickGyver »

bnz99 wrote: Thu Apr 29, 2021 9:49 am 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
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Re: 128MB SDRAM v2.9

Unread post by dmckean »

Newsdee wrote: Fri May 14, 2021 1:18 pm Is anybody selling these new versions yet?
I know that Ultimatemister is.
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Re: 128MB SDRAM v2.9

Unread post by Newsdee »

dmckean wrote: Fri May 14, 2021 6:39 pm I know that Ultimatemister is.
It's listed as 2.9, but the picture looks different. Has anybody ordered it yet?
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Re: 128MB SDRAM v2.9

Unread post by warham »

Newsdee wrote: Sat May 15, 2021 1:22 am
dmckean wrote: Fri May 14, 2021 6:39 pm 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
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Re: 128MB SDRAM v2.9

Unread post by 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?
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Re: 128MB SDRAM v2.9

Unread post by hiddenbyleaves »

Fuzzball wrote: Sat May 15, 2021 9:17 am 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.
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Re: 128MB SDRAM v2.9

Unread post by robinsonb5 »

warham wrote: Sat May 15, 2021 6:40 am 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.
Fuzzball wrote: Sat May 15, 2021 9:17 am 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.)
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Re: 128MB SDRAM v2.9

Unread post by pbsk8 »

Fuzzball wrote: Sat May 15, 2021 9:17 am 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
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