Bricked Neo Zemmix

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Por PipoBimbo

Supporter (12)

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24-11-2014, 22:38

Verdict for 33RC3 TEST B : BAD Sad

Por KdL

Paragon (1441)

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24-11-2014, 23:23

Thank you for testing. Big smile
I think it is a good solution to build many variants and find out at last the right one.
However it is required a final release before that!

Por robinsonb5

Supporter (10)

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30-11-2014, 01:56

Have you identified the root cause of this problem yet?
It reminds me of a problem that affected the Atari 800 core on certain DE1 dev boards, where the SRAM chip was a slightly different type and needed on-chip termination turned on. Do the affected boards have a particular type of SDRAM chip, perhaps?

Por KdL

Paragon (1441)

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30-11-2014, 20:32

Sorry, I don't have a bricked zemmix neo here... no other idea Sad

Por robinsonb5

Supporter (10)

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30-11-2014, 21:09

OK - well I don't have one either, I'm just intrigued by the problem.

If we can figure out what's different between boards on which core works and boards on which it doesn't we might be able to find a solution.

If it's a different type of SDRAM then it should be fixable by changing drive strength settings and/or adding timing constraints.

If the difference is a lower FPGA speed grade on the non-working boards it'll be harder to fix, but again, it's possible timing constraints or tweaking drive strength will help.

I don't know how easy it is to access the motherboard of a Zemmix Neo, but if it's easy, could anyone post the exact model number of the Altera Cyclone chip (starting EP1C12..., especially the speed grade at the end - either 6, 7 or 8), and also the model number of the SDRAM chip (which I think will be the only other large chip on the board.) If we can compare those numbers for working and non-working board we will have some clues to go on.

Por KdL

Paragon (1441)

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02-12-2014, 00:22

Yes, good idea, someone wants send a jpg???

Por PipoBimbo

Supporter (12)

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02-12-2014, 21:19

It's very hard to see the numbers on the cyclone chip, here's what I'm guessing so far :

Altera :
1C12Q240CBN

RAM :
SAMSUNG 628
K4S561632E-TC75
S5616 WEF208XT

Por robinsonb5

Supporter (10)

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02-12-2014, 22:03

PipoBimbo wrote:

1C12Q240CBN

Probably C8N at the end, which would make the chip speed grade 8.

Quote:

K4S561632E-TC75

OK and that's the exact SDRAM chip specified in the OneChipMSX Schematics.

Thanks for that. And is this a Zemmix Neo or a Zemmix Neo Lite?

Por mygodess

Champion (275)

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03-12-2014, 01:09

I used the cpu and ram on ocm schematic.
If the zemmix neo is not working then I can change the altera cyclone here but the problem is shipping. (very expensive)
I think epcs4 and ram have no problem but cyclone could have. When I soldered the Zemmix Neo, cyclone error rate was very high as I mentioned. If you can change the cyclone there, it would be good..

Por KdL

Paragon (1441)

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03-12-2014, 02:52

at least an attempt would not hurt Wink

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