AX5202P MMC3 clone pinout?

Sorry to necro another old post! But i recently got my hands on about 10 of these AX5202p chips. I designed a basic TLROM board and tested with "Little Nemo: The Dream Master", and sadly only 4 of the chips work! The others either don't load at all, crash after selecting Start Game, or have completely messed up graphics. I've heard that some of these MMC3 clones can be a little hit and miss, but for half of a lot to not work is brutal odds.

So, my question is how or what would cause these chips not to work anymore, and in differing ways? As far as I can see these were new (well, new old stock anyways), so it can't have been from misuse. Or, is it possible that these AX5202p chips have different pinouts/functions?

I've read that among MMC3 features in these clones, the IRQ circuitry has the lowest yield. Try them with Holy Diver Batman; does anything but IRQ (third digit of result code) fail on them?

I had the same problem, out of the 10 that I tested, only 2 worked, some where partially working. Funniest one was where everything but IRQ worked, so SMB3 was playable without the status bar. I have some more tubes of them that weren't tested. It didn't look very promising, plus I don't have a board for it (was using a friends' board when we tried those 10), I never bothered to make one.

I don't know if we could ever know for sure, but my theory is that all the good chips were built into carts years ago, these were from a known bad batch that was set aside and never used, or were thrown out and someone pulled them from the trash. I have a hard time believing that that many defects could be normal, but I suppose that's possible too.

Can you upload a picture of your chip?
I use this and never had any problem with them
It seems its date code is 1998

I have the exact same chips, even the date stamp is the same. Any idea what the issue is here?

Mine look similar, but the codes are different, 012823A 0016

What do these things go for? Curious if it would be worthwhile to make a CPLD breakout board that was pin compatible with the AX5202P for dev use like this.

@ infiniteneslives
Using these clones will salvage the remaining original NES/Famicom cartridges

Not necessarily... they are still available from some online places, but if they only half-work then whats the point?

I've attached a couple pics of what my issues are. One is a working chip, the other 2 not so much.

From the pictures I say they are defected for sure
Were they used when you bought them?
You need to adjust the pins (bend a little manually) of an unused chip to insert it into the IC socket, this is a sign of a new chip
Also these chips are very sensitive to static electricity and they must carried or shipped inside of a special tube

ps : very nice controller you have, I have the same thing and works perfect, nes controller with snes style

Yeah all of the pins had to be bent slightly to get them into my socket. They came in a tube in a static-free bag, so I'm not sure what could have happened there... I spoke with the place I bought them from and they told me "they can't be faulty, the manufacturer has said they were new and unused", but they sure appear faulty to me...

BTW, the ones that do that blue garbled screen also get very hot after a minute, and have a scrolling humbar vertically. Almost what you'd expect if you reversed VCC and GND or something, but the chip was inserted correctly.

It's possible they're mis-labeled.

They could be the VRC4 clone or the alternate MMC3 type. I know of at least two different pirate MMC3 pinouts.

Have you got the pinout differences?

Pinouts for 2 different MMC3 clones are at Romlab http://nintendoallstars.w.interia.pl/romlab/pmmc3.htm

Mislabeling is possible I suppose, if they were mixed together somehow. The working ones definitely seemed to work, tests I did were with SMB3 and Double Dragon 3.

Yeah the ones that worked for me worked great as well. Tested with Batman, Megaman 3 and 5, Little Nemo. But these other ones baffle me...I don't think it could be a mislabel on some of these, as the game appears to work somewhat, albeit very glitched out. The other chips pinout is way too different for the game to even get that far.

How many of them are defected?
Are they defected in the same way?
For example 6 or more of them have the same behavior and output

Of the 10 I tested, only 2 worked right. It was several years ago, but I remember the defective ones mostly glitched in different ways. I'm pretty sure at least one of them got really hot too, like getafixx reported.

I think that has a substantial chance of something along those lines being the case. When I first heard about this being a common issue with these chips I had a hard time coming up with a rational explanation for the high rate of defect. At that time part of me wondered if it was just bad testing practices by whoever was making those reports years ago. But here you are years later with a separate batch of chips and having the same issue. I have since gained experience in IC manufacture and testing, knowing what I know now, this really isn't too suprising with NOS. FWIW I purchased a number of yamaha synths from ebay a couple months back and found only 1 of 5 pcs I purchased actually worked properly.

In IC manufacturing parts are practically always tested after assembly/encapsulation because there will always be defective parts during the assembly (wire bond and encapsulation) process. You have to ask yourself what happens to those parts which fail testing? If they're deemed unusable all you can really do is toss them in the trash. If some worker thought they might be able to pull them out of the trash to sell them on a black market of sorts chances are decent that they would have yanked em. One might wonder, well then why do some of them work? In testing there are always false failures, and additionaly a part can fail for reasons besides gross functionality. Perhaps those didn't meet all the timing specs, or they had too high of current consumption based on the spec etc. And the true failures aren't all going to fail the exact same way, they'll have varying issues which is exactly what you're seeing. More over you would probably expect that ~20-50% of the parts you 'throw away' are functional in practice. So that gives even more reason to pull them from the trash and have them end up in your hands 20 some years later. The person/company who sold them to you certainly didn't manufacture them, and they certainly didn't test them. So if whoever sold them to your distributor pulled them from the trash at some point, you'd have to expect what you're seeing.

They're just plain bad parts, not really worth your time and effort to investigate further IMO. Be happy with the working ones you have as proof that your testing apparatus works.

And thats more than likely whats going on. Well, it was great while it lasted

I found a pinout of another MMC3 clone.
Its pin31 is named : DLYED phi2
How can I find out if this is the same pin for AX5202P (pin39)?

Delayed Phy2 = M2 (with delay added)

That new MMC3 clone you found the pinout for is the one which is usually marked "88" on top.

So it is the same as this?

lidnariq suggested adding a resistor and capacitor



What else it can be used for?

I think delayed M2 may be useful to prevent glitching the data written/read when accessing WRAM.

That resistor circuit is what Konami VRCxx cartridges use for delay when they have WRAM in them.

What he said.

Delayed M2 is necessary to distinguish between writes to WRAM and writes to registers, because in a normal NES, M2 rises before /ROMSEL falls. Thus, there is a very brief moment that looks like a write to $0000-$7FFF when it's actually a write to $8000-$FFFF.

Hey guys,

I just stumbled upon this shop:

http://www.muramasaentertainment.com/in ... basic.html

It was recommended by me by youtube. I still think the clones are somewhat unreliable. That guy seems to be confident enough to sell them.

And no, thats not neither my shop nor do I know the owner.

But maybe he discovered a "safe source" for the clones.

I kind of doubt there was a "safe source", honestly. I had used them for a while and found that every now and then there were some that wouldn't handle SRAM at all, or would have bad IRQ timing. He may be in for some people coming back saying the boards are faulty, for sure.

Buying anything like that out of China is a gamble at best. These parts are 20+ years old, even if they are "new-old" stock.

Curious what the best pricing was on these that you found when buying in bulk? Realizing the effective price is then inflated by DOA's etc.

Back then it was probably $3USD a piece. And yeah, after you factor all the DOA ones in it was really rather costly.

About what I figured.. Nearly at the point where a guy could compete with the chip directly by designing up a 'breakout board' MMC3 for hobbist use. Ideally such a little board would be the same footprint and pinout as AX5202P for lack of a better standard. That would require something like dual XC9572XL or LC4064V to fit in DIP-40 footprint. That would run somewhere on the order of $5 of hardware though making it a loosing battle. 0.6" DIP is too narrow for TQFP-100 package unfortunately that would be needed to compete at $3 price point. Would have to jump to 0.7" wide DIP to support TQFP-100 package CPLD, and in that case you might be better off brewing up your own footprint/pinout to something more square for space optimization..

Wouldn't even have to do that. Just surface-mount 90 degree dip headers to the underside of the board, and then you can use the existing footprint.

Good call, although then the question is if fitting within AX5202P footprint is worth the added assembly complexity.

However the nature of such a product would suggest the user will be skilled enough to solder the SMT header themselves. Could integrate SMT male header at 0.6" pitch, and TH male header at 0.7" pitch into same layout.

Well if it was developed to be a hobbyist board, then you could use whatever footprint you wanted, really. I was just saying in the case of these specific boards, the same footprint could be used with the SMT headers.

If someone were developing their own code though, it would be ideal to use the AX5202P footprint so that they know for sure the board works as intended before they start writing their own mapper. Add a socket, try out the pirate mapper to verify the board works, and then replace it with a CPLD with some JTAG pins for easy programming.

Probably not worth all the effort, but it would be useful if someone were trying to utilize a board that was already built, instead of designing a new one.