MAD-1 Replacement SRAM Battery Backup?
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1. NO BLATANT PIRACY. This includes reproducing homebrew less than 10 years old, with the exception of free software.
2. No advertising your reproductions, with the exception of free software.
3. Be nice. See RFC 1855 if you aren't sure what this means.
Re: MAD-1 Replacement SRAM Battery Backup?
Your problem lies with your decoder, not your save circuit.
You can't just copy what Nintendo did and expect it to work. A 1a3b cart is limited to 1mb rom size and yet, you're trying to run a 3mbit game. Your data busses are like boxers - fighting with themselves. A decoder is the traffic-cop of databusses allowing only 1 databuss to talk at a time. You have a rom and a ram - hence two databusses both trying to talk at the same time.... which = crash and black screen.
That's why the game boots and then crashes as soon as it looks to the sram for information.
Well..... the above is my supposition as I don't have a full picture of how you have things connected. So it's my best guess.
Most on this forum are glad to help, but help point you in the right direction so you can find the answers on your own. The joy of learning
You can't just copy what Nintendo did and expect it to work. A 1a3b cart is limited to 1mb rom size and yet, you're trying to run a 3mbit game. Your data busses are like boxers - fighting with themselves. A decoder is the traffic-cop of databusses allowing only 1 databuss to talk at a time. You have a rom and a ram - hence two databusses both trying to talk at the same time.... which = crash and black screen.
That's why the game boots and then crashes as soon as it looks to the sram for information.
Well..... the above is my supposition as I don't have a full picture of how you have things connected. So it's my best guess.
Most on this forum are glad to help, but help point you in the right direction so you can find the answers on your own. The joy of learning
Re: MAD-1 Replacement SRAM Battery Backup?
I'm glad for any help and always love to learn something new.
Also, I'm using my own decoder's pinout which has been proven to work for up to 32MBit ROMs.
Pinout as follows:
EPROM /OE is connected to Address Decoder
EPROM /CE is connected to GND
Even tried connecting EPROM /CE to RAM /OE and SNES/CE. No difference. Game freezes after Nintendo Logo.
Also, I'm using my own decoder's pinout which has been proven to work for up to 32MBit ROMs.
Pinout as follows:
Code: Select all
__ __
SNES #49 |01\/16| +5V
SNES #40 |02 15| Pin 04
SNES #40 |03 14| A20
Pin 15 |04 13| A21
NC |05 12| NC
NC |06 11| NC
ROM /OE |07 10| NC
GND |08 09| RAM /CE
------
EPROM /CE is connected to GND
Even tried connecting EPROM /CE to RAM /OE and SNES/CE. No difference. Game freezes after Nintendo Logo.
Re: MAD-1 Replacement SRAM Battery Backup?
I'm not at my desk so I say this from memory... I don't think pins 2/3 is right. And the /CE should be connected.Ice Man wrote:I'm glad for any help and always love to learn something new.
Also, I'm using my own decoder's pinout which has been proven to work for up to 32MBit ROMs.
Pinout as follows:
EPROM /OE is connected to Address DecoderCode: Select all
__ __ SNES #49 |01\/16| +5V SNES #40 |02 15| Pin 04 SNES #40 |03 14| A20 Pin 15 |04 13| A21 NC |05 12| NC NC |06 11| NC ROM /OE |07 10| NC GND |08 09| RAM /CE ------
EPROM /CE is connected to GND
Even tried connecting EPROM /CE to RAM /OE and SNES/CE. No difference. Game freezes after Nintendo Logo.
When you say A21, A20, are you accounting for skipping A15?
Re: MAD-1 Replacement SRAM Battery Backup?
Relabeling things a little:This is consistent with nocash's description of the MAD-1-
(namely, when jumpered for LoROM, /ROMCE is low when /ROMSEL is low and SNES A15 is high, and /RAMCE is low when /ROMSEL and SNES A15 are low AND SNES A20, A21, and A22 are high)
SNES A22 doesn't explicitly need to be decoded because A22 is necessarily high if /ROMSEL and SNES A15 are low.
Code: Select all
.--\/--.
/ROMSEL |01 16| +5V
SNES A15 |02 15| Pin 04
SNES A15 |03 14| SNES A20
Pin 15 |04 13| SNES A21
NC |05 12| NC
NC |06 11| NC
ROM /CE |07 10| NC
GND |08 09| RAM /CE
'------'
(namely, when jumpered for LoROM, /ROMCE is low when /ROMSEL is low and SNES A15 is high, and /RAMCE is low when /ROMSEL and SNES A15 are low AND SNES A20, A21, and A22 are high)
SNES A22 doesn't explicitly need to be decoded because A22 is necessarily high if /ROMSEL and SNES A15 are low.
Re: MAD-1 Replacement SRAM Battery Backup?
@Markfrizb: Since I used that pinout on a modified 1A3B board with a 32 pin MaskROM and tested it successfully on many 2-4MB LoROM games (LoT:ALttP, Super Metroid Hacks, Super Mario World Hacks, etc.) and they all saved and worked fine that way.
But if you happen to have another pinout once you're able to check, I wouldn't mind to try that one either.
I just can't imagine it is the decoder's problem.
But if you happen to have another pinout once you're able to check, I wouldn't mind to try that one either.
I just can't imagine it is the decoder's problem.
Re: MAD-1 Replacement SRAM Battery Backup?
I'm out of town on business so I won't be able to check til later on, but if this decoder on previous 3-4mB builds have worked before, then maybe your save circuit isn't enabling the sram? Maybe It's keeping it disabled all the time....Ice Man wrote:@Markfrizb: Since I used that pinout on a modified 1A3B board with a 32 pin MaskROM and tested it successfully on many 2-4MB LoROM games (LoT:ALttP, Super Metroid Hacks, Super Mario World Hacks, etc.) and they all saved and worked fine that way.
But if you happen to have another pinout once you're able to check, I wouldn't mind to try that one either.
I just can't imagine it is the decoder's problem.
Re: MAD-1 Replacement SRAM Battery Backup?
Funny thing is, I changed the capacitor from 100nF to 10nF on my SuperCIC PIC and the game didn't freeze but I got the anti piracy screen. I'm sure I'm using the wrong components or doing something wrong. Even removed the 100nF cap for the EPROM completely, but no difference.
The parts I'm using are:
CR2032
2x 1N4148
1x 1k Ohm
1x 100k Ohm
2x 100nF Ceramic Cap (for EPROM and SuperCIC)
Even while trying to copy the 1A3B logic completely (with original parts found on a 1A3B board), it does not work, while in theory, it should. o_O
Even tried to connect VCC and GND directly to the cart edges with wires instead but it didn't change anything.
I'm kind of lost here. It's the only puzzle left to finish the cart. :'(
The parts I'm using are:
CR2032
2x 1N4148
1x 1k Ohm
1x 100k Ohm
2x 100nF Ceramic Cap (for EPROM and SuperCIC)
Even while trying to copy the 1A3B logic completely (with original parts found on a 1A3B board), it does not work, while in theory, it should. o_O
Even tried to connect VCC and GND directly to the cart edges with wires instead but it didn't change anything.
I'm kind of lost here. It's the only puzzle left to finish the cart. :'(
Re: MAD-1 Replacement SRAM Battery Backup?
Could make a trivial batch that bypasses the antipiracy check, I suppose... But I don't think it'll help, I think you'll just get new different exciting bugs.
Re: MAD-1 Replacement SRAM Battery Backup?
With the anti piracy screen on I can check if the SRAM is working or not. Quite handy in this case, heh. But sadly it does not work yet. I will check it again tomorrow and check everything there is...hoping to find the mistake.
Re: MAD-1 Replacement SRAM Battery Backup?
Yeah, so I connected VCC and GND directly to the cart connectors as well as the GND net. Used all parts found in an 1A3B board and connected them the same way. It does not work. I give up for now. I have no idea what's wrong..
Re: MAD-1 Replacement SRAM Battery Backup?
After some more testing and finding a mistake in address decoding, still no success.
I accidentally decoded A19/A20 instead of A20/A21 but even with the fix, no SRAM detection.
If I use a MAD-1 on my board the SRAM works like a charm.
Now another question. Did someone actually try to get an identical IC like the MAD-1 or knows where to get any without using any donors?
And how possible is it to actually use a PIC as decoder instead?
I accidentally decoded A19/A20 instead of A20/A21 but even with the fix, no SRAM detection.
If I use a MAD-1 on my board the SRAM works like a charm.
Now another question. Did someone actually try to get an identical IC like the MAD-1 or knows where to get any without using any donors?
And how possible is it to actually use a PIC as decoder instead?
Re: MAD-1 Replacement SRAM Battery Backup?
Have you been using my simple test program?Ice Man wrote:After some more testing and finding a mistake in address decoding, still no success.
I accidentally decoded A19/A20 instead of A20/A21 but even with the fix, no SRAM detection.
I know certain people are making repros using 74'139s, as you were trying to...Now another question. Did someone actually try to get an identical IC like the MAD-1 or knows where to get any without using any donors?
One of the modern ones with CLCs could do it; that's basically just a tiny bit of programmable logic glued onto a microcontroller.And how possible is it to actually use a PIC as decoder instead?
Could even stuff it into the same physical IC as has the SuperCIC...
Re: MAD-1 Replacement SRAM Battery Backup?
Crap, I honestly forgot about that. I will try it later today.
Though, what am I looking for exactly with the memory viewer?
The SRAM will most likely be empty.
Though, what am I looking for exactly with the memory viewer?
The SRAM will most likely be empty.
Re: MAD-1 Replacement SRAM Battery Backup?
Open bus looks like a solid region of memory filled with the bank byte (in this program).
(i.e. reading from $6F0000 on your 1A3B-equivalent should show 512 bytes of $6F, and if the RAM works, you should see something other than 512 bytes of $70 at $700000)
(i.e. reading from $6F0000 on your 1A3B-equivalent should show 512 bytes of $6F, and if the RAM works, you should see something other than 512 bytes of $70 at $700000)
Re: MAD-1 Replacement SRAM Battery Backup?
Game is saving now!
I connected a 100k resistor between SRAM VCC and CE line as well as connecting 100k + 1N4148 between Batttery+ and SRAM VCC and an additional 1N4148 from VCC to SRAM VCC.
SRAM +CE is connected to VCC
SRAM /OE is connected to Cart #23
All ICs got a 100nF capacitor as well.
I connected a 100k resistor between SRAM VCC and CE line as well as connecting 100k + 1N4148 between Batttery+ and SRAM VCC and an additional 1N4148 from VCC to SRAM VCC.
SRAM +CE is connected to VCC
SRAM /OE is connected to Cart #23
All ICs got a 100nF capacitor as well.