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PostPosted: Thu Jan 03, 2013 2:49 am 
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When you make your own board, you don't need any "adapter", since you make all "adaptions" in the board itself.

And yes, I use 27C322, but I'm thinking of 29LV3211, which are smaller, 8 bits bus width, and less power consumption. It's the best way to overcome those space limitations on the board, since 27C322 are too big. The problem with 29LV3211 is that it's powered with 3.3V, so the logic levels are not compatible.


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PostPosted: Thu Jan 03, 2013 8:19 am 
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Yep, it would be pretty hard to get 3 of those 42 pin monsters on a cart, you are right. I was referring to the tsop adapters. There is a discussion on here about the low voltage flash roms and level translators to use the LV roms.
In my design, i would still use the tsop adapter as I, like many, am not very good at soldering those tiny legs on a pcb. So I prefer to use the adapters. Even so, getting 3 of the tsop adapters would still pose a challenge. But making a 64m adapter would get rid of one of them. Too bad the 64m 5v flash roms are really hard to find. :(







I'm still learning. :)


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PostPosted: Thu Jan 03, 2013 11:35 am 
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magno wrote:
When you make your own board, you don't need any "adapter", since you make all "adaptions" in the board itself.

And yes, I use 27C322, but I'm thinking of 29LV3211, which are smaller, 8 bits bus width, and less power consumption. It's the best way to overcome those space limitations on the board, since 27C322 are too big. The problem with 29LV3211 is that it's powered with 3.3V, so the logic levels are not compatible.


Aren't the 29L3211 chips 16-bit? How do would you wire it to run in 8-bit mode?

I know they can be used in the actual Star Ocean cart (SDD-1) as a drop in replacement, using a voltage regulator to step down to 3.3V. But there are also the 26L6420 chip which is 64Mbit, or alternatively the 26L12811 which is 128Mbit (that would be ideal, as it would require only 1 chip). All of those are in the same 3.3V SOP44 package.


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PostPosted: Thu Jan 03, 2013 12:00 pm 
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getafixx wrote:
the 26L12811 which is 128Mbit (that would be ideal, as it would require only 1 chip)
The datasheet I found (for the MX26L12811MC) says it can only be used in word mode...
Also, I'm not altogether convinced you could have safely used it in a 5V system without level shifters or creative interpretation of the datasheet (by e.g. running it at 4V and relying on the 1V official overvoltage allowance)


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PostPosted: Thu Jan 03, 2013 12:07 pm 
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lidnariq wrote:
Also, I'm not altogether convinced you could have safely used it in a 5V system without level shifters or creative interpretation of the datasheet (by e.g. running it at 4V and relying on the 1V official overvoltage allowance)


Over at racketboy forums: The 29L3211 in a Star ocean cart using an AMS1117 3.3V voltage regulator.

http://www.racketboy.com/forum/viewtopi ... &start=520


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PostPosted: Thu Jan 03, 2013 12:16 pm 
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Sorry, I didn't mean that as "it won't work". I meant "I fear that slightly exceeding the rated capabilities of the IC will cause premature failure"

That said, his solder jobs are beautiful.


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PostPosted: Thu Jan 03, 2013 12:17 pm 
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getafixx wrote:
Aren't the 29L3211 chips 16-bit? How do would you wire it to run in 8-bit mode


No, they aren't. You can set them in word or byte mode by tying pin 33 to GND or Vcc. Anyway, if they were 16 bit only, you could multiplex their output.


lidnariq wrote:
Also, I'm not altogether convinced you could have safely used it in a 5V system without level shifters or creative interpretation of the datasheet (by e.g. running it at 4V and relying on the 1V official overvoltage allowance)


No, you SHOULDN'T do that. The datasheet is crystal clear about that: absolute maximum 4V supply, typical 3.3V+10%. I don't know where you read that "1V official overvoltage allowance", but the "[b]Absolute Maximum Ratings" can't be never exceeded. Anyway, the problem in using 29LV3211 is not the power supply (linear regulators are cheap as hell) but the Vih: the HIGH output level is, at least, 2.4V and at most, 3.3V and the TTL HIGH input level is, at least 2V. At first glance, you may ask where the problem is, because 2.4V is higher than 2V so the TTL logic after the 29LV3211 flash should sample the proper logic value, but this becomes fussy when there are long traces between flash and CPU, an edge connector and supply noise in each digital chip (specially, those synchronous to the MCLK). It's confirmed that 29LV3211 flash memories cause problems when used directly as a mask ROM replacement. They MIGHT work when used connected to some special chip like SA-1 or Super-FX, but not 100% reliable either.


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PostPosted: Thu Jan 03, 2013 12:30 pm 
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Interesting. From the way they were talking on racketboy I figured they had been working great... Maybe its just in conjunction with the SDD-1 chip that they seem to work good?


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PostPosted: Thu Jan 03, 2013 12:30 pm 
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magno wrote:
No, you SHOULDN'T do that. The datasheet is crystal clear about that: absolute maximum 4V supply, typical 3.3V+10%. I don't know where you read that "1V official overvoltage allowance", but the "[b]Absolute Maximum Ratings" can't be never exceeded.

The datasheet I saw (MX26L12811MC, P/N PM0990, REV 1.0 OCT 29 2003) said:
page 1: Latch-up protection is proved for stresses up to 100 milliamps on address and data pin from -1V to VCC + 1V ← here
page 21:
Code:
ABSOLUTE MAXIMUM RATINGS
[…]
Voltage with Respect to Ground Voltage on any signal ……… -2.0 V to 5.0 V
[…]
Notes: 1. […]Maximum DC voltage on input or I/O pins is Vcc + 0.5V. During voltage transitions, input or I/O pins may overshoot to VCC + 2.0V for periods < 20 ns.
[…]
OPERATING RATINGS
Vcc Supply Voltages
Vcc for full voltage range……… +3.0 V to 3.6 V
Operating ranges define those limits between which the functionality of the device is guaranteed.

You'll note, that the OR is not an AMR. But yes, it's still a terrible plan.


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PostPosted: Thu Jan 03, 2013 12:54 pm 
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You are talking about MX26L12811MC and I'm talking about MX29LV3211, nothing to do one with the other. The 29V3211 is pretty clear about all what I said before.
Anyway, connecting this flash memory to S-DD1 doesn't guarantee it will work. S-DD1 reads from the flash to decode data or to pass-through data to the SNES, so stressing the S-DD1 could corrupt some of the bits because of the 2.0V high level detection.


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PostPosted: Sun Feb 24, 2013 8:20 pm 
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Well, i've been tinkering with this 96mbit Star Ocean project for a couple months, and have made no headway at all. I got a linear rom from Mottzilla (thanks again!) that I hoped was the answer, but when i broke it down into three 32mbit parts and soldered it all to a cart, it still didnt work. I then doubled back to this thread and checked again what was posted earlier, about the different rom sections (C0-FF:0000-FFFF, 40-7D:0000-FFFF, 00-3F/80-BF:8000-FFFF) and it still makes no sense to me. Maybe that makes me daft, but I'm still new to all this.

Can anyone break this down a little for me? I just can't seem to understand how I need to order the rom file, and split it... and seeing as RetroUSB no longer sells Star Ocean, I really want to be able to make this work without gutting a donor. Whatever I have tried thus far has clearly been incorrect, and it looks like the only thing I'm missing is the rom ordering. I have followed the '139 pinout to work according to shadowkn55, but to no avail.

Can anyone help me out?


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PostPosted: Mon Feb 25, 2013 9:34 am 
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I got this from somewhere, does that help?


If you use a hi-rom board with a mad-1 decoder as a donor, all you need is a 74xx139 to access the entire rom memory space.

1. MAD-1 #4
2. MAD-1 #12
3. GND
4. ROM 3(00-3F/80-BF:8000-FFFF)
5. Connected to Pin 15
6. NC
7. NC
8. GND
9. NC
10. NC
11. ROM 1(C0-FF:0000-FFFF)
12. ROM 2(40-7D:0000-FFFF)
13. GND
14. A23
15. Connected to Pin 5
16. VCC

The rest is basically what kind of memory you decide to use for the rom. ROM 1 and 2 are hooked up like hi-rom games (use A15) and ROM 3 would be hooked up like lo-rom (ignore A15).


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PostPosted: Mon Feb 25, 2013 9:43 am 
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Yeah that was mentioned previously in this post, as well in that file you sent me. however, it doesnt explain which parts of the rom get moved around before the files are split.


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PostPosted: Mon Feb 25, 2013 6:46 pm 
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I would guess that you should be able to split it into three even 32mb pieces.

Given the names ROM 1, 2, and 3 I would suspect that those refer to the 1st, second, and last 32 megabit pieces of the 96 megabit ROM. That means on ROM 3, you need to skip A15 when wiring that ROM to the board. For HiROM the signals on the Maskrom connect as you suspect, A15 to A15, A16 to A16. But on LoROM, which this 3rd ROM is, you skip A15 on the ROM socket, and instead connect the ROM 3 EPROM's A15 to A16 on the Board Socket. A16 goes to A17 on the board socket. And so on.

That's my understanding, but I may be incorrect. I have never made a Star Ocean 96 meg cartridge before.


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PostPosted: Mon Feb 25, 2013 8:42 pm 
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I might have to give that a try... I figured he was talking about how the '139 was wired to the MAD-1 it would register the first 2 roms as Hirom, and the last as lorom. Maybe its as you say?


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