The Dangers of using 3.3V Flash Carts in Retro Consoles

[ClodBuster]

The console hardware itself suffers too anyway, since there's flow from both console to cart, as well as cart to console.

Please read what Zeta said about it.

[SamIAm]

Wouldn't any signals sent from the flash to the console be at 3.3V, and therefore not cause any overvoltage/overcurrent problems?

The whole theory of Rene's big article is that clamping diodes in Everdrive flash cause shorts when hit with 5V from the console, and that these shorts drain shitloads of current even with resistors in the way. This effect may be true to an extent, but the actual amounts don't seem to be anywhere near the estimates.

[ClodBuster]

From my understanding, the console needs signals upped to 5V again.

Have you read what Zeta said in this thread?

[SamIAm]

Yes. Twice. I don't get what your getting at.

If there isn't too much current being drawn, where is the problem? Where is damage being caused?

Again, nobody really cares about the flash chip in the Everdrive. Those are replaceable and obviously don't have a terribly high failure rate under the current usage.

[ClodBuster]

Dave
July 10, 2017 at 21:11

Krikzz did not do what I would consider to be a good test there – he should have run the game for 30 seconds and then run the same game in the Everdrive. I’m no electrical engineer, but I really suspect that running game code might require a bit more electrical power through the cart instead of a static screen that says that there is no card present – I mean, there is no activity on the cart. But that’s just me. I’d be interested to hear Rene’s thoughts.

Source: https://db-electronics.ca/2017/07/05/the-dangers-of-3-3v-flash-in-retro-consoles/#comment-2908

[SamIAm]

Yes, I'm curious about that, too.

Would you agree that a game running normally on the Everdrive without a significant increase in current consumption would indicate that there is no trouble?

[ClodBuster]

I'm not enough into digital electronics that I could give you a qualified answer.



However, I can tell you several quirks about Krikzz measurement video:

1. He should have used an oscilloscope to probe into the circuit, since the voltage and current characteristics aren't strictly DC when dealing with digital electronics.
2. He should have shown both voltage and current at the same time - Best done on a 2-channel scope or with one DMM in series and one DMM in parallel. Since he's not showing the voltage readout, he could feed the Everdrive with whatever voltage he feels comfortable with, unbeknownst to the viewer.
3. Uni-T multimeters suck. Here's why.



Also, I think we all can agree on the fact that Krikzz will pull anything out of his head, just to save him from customer claims.

[Black Tiger]

All of krikzz claims don't matter as long as his stuff is running outside of the specifications.

If he would be as eager redesigning his flash carts to comply with the chip's and console's specs as he is in denying simple facts...

I believe that it was his first response in which he said that he has been with new versions and that he agrees about the need for something still not addressed to be taken care of in some of them.

[ClodBuster]

That's good. But this also means Krikzz DOES admit that the majority of his Everdrive designs are bad.
While on the other hand, he STILL tries to make his customer base believe that all concerns are ill-founded.

What a hypocrite.

[SamIAm]

Of course, I would like to see more consoles tested, using more original carts, and with better equipment - good multimeters at least, oscilloscopes if possible.

However, Rene's article was all about how the diode clamps in the Everdrive flash are almost constantly activating and drawing huge, devastating volumes of extra current through vulnerable parts like the CPU. Now, it looks like the effect may not be happening at all, and if it is, it's likely far less severe than Rene estimated. He could have, and should have, tested this theory before publishing. It also would have been good form to get a statement from Krikzz beforehand.

A fellow posted this on his forum:

Just as a test I threw my mega everdrive on my opened test bed and was looking for voltage spiking and temperature issues. Guess what? NOTHING. It's been on for about 3 days now. I have a temperature monitor on it just to see what happens and the temperature variance I'm seeing is +/- .5 degrees C. Completely within the limits. I'm also not seeing any abnormal spikes.

Krikzz also said this about the resistors:

2. Moreover, I highly suspect the addition of R1 comes from a misinterpretation of Altera app note AN258 

R1 comes not from misinterpretation of Altera app note AN258, first of all i used it because directly connected flash works fine for reading, but writing almost always ends with errors.

Optimistically, we could say that it looks like it's never been about protection and always been about accuracy.

It may yet turn out that there is major current being drawn during bus access and that Krikzz is not being forthcoming. A 25mA increase, however, is pretty underwhelming given what Rene was saying. Give me a few more results like that, and I'll continue to use all my old Everdrives without fear.

[Gypsy]

I have a couple scopes but no everdrive or I'd test. Seems like it will end up not being a big deal though.

[sirhcman]

So when does the class action lawsuit start?

[SamIAm]

https://www.youtube.com/watch?v=kx3M9Z4RAok&feature=youtu.be

Multiple minutes of a real cart (different from last time) and an Everdrive playing the same game. Difference is still right around 25-30mA.

When Krikzz says "this difference mostly due the normal power consumption of own cartridge components" I'm inclined to believe him.


Also, from Rene's article's comments:

1) cartridge bus activity is not really related or proportional to what is happening on screen. CPU is what is driving the address lines and reading data from Flashcart and it still runs the same if this is a static or animated screen, i.e read new instructions/data from ROM area every 4 cycles at most. Actually, the least complex instruction loop (NOP) is what would stress the cartridge bus the most, not the opposite.

2) current consumption is more directly impacted by the number of pins set high on average than number of cartridge access. To test maximal current consumption you would have a test ROM that continuously read FFFFh from address 3FFFFFh (which is max ROM address) but that wouldn’t be a realistic test case either since that’s definitively not what normal games are doing.

[SignOfZeta]

Does anyone have Pier Solar and an infrared pyrometer as mentioned in the podcast? I'm interested in that test since anything that makes the outer case of the cart measurably warmer is probably pulling more than 25mA.

What Kriz says about Everdrives is important but there are loads more devices with mismatched parts that are aparentky even shittier and less thoughtfully designed. Those ubiquitous yellow multicarts for MVS for example, there seems to be more anecdotal evidence claiming they kill boards. 

EDIT:  btw, 25-30mA doesn't seem like a lot, but if it's all coming from just the flash, CPU and RAM it might be. Knowing what a normal consumption of just the bus would help. He's measuring consumption of the entire system, of which heat dispation from CPU/RAM is but a tiny portion. For all I know consumption by sensitive componants has tripled. Has this been discussed to death anywhere yet?

[Gredler]

Those ubiquitous yellow multicarts for MVS for example, there seems to be more anecdotal evidence claiming they kill boards. 

For me this is the main take-away from this thread. Avoid those cheaply made multicarts and pirate carts, I suppose?