(SNES)Help With Circuit for LoRom M27C322

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Kayumba
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Joined: Sun Mar 01, 2020 2:36 am

Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Thu Jul 16, 2020 4:08 pm

lidnariq wrote:
Thu Jul 16, 2020 2:57 pm
Kayumba wrote:
Thu Jul 16, 2020 2:22 pm
"Standby Voltage-Min" Is that the same?
Yes, probably.
HM6264ALP-10 -> Min Supply voltage : 4.5
For both Hitachi parts, look at the page "Low Vcc Data Retention", where the line is given:
"Vcc for data retention Vdr min: 2.0V"

For the Rohm part, the words "Can maintain information at voltages as low as 2 V" on the front page, or "Data holding characteristics at low voltage", "Voltage required to hold data" is the important bit.
Oh yeah, I see.

BR6216B 10LL -> Voltage required to hold data : Min 2 v
http://www.icpdf.com/icpdf_datasheet_4_ ... .html#view (Screen Page 3)
To order: https://fr.aliexpress.com/item/32476331 ... 6c37WoJKUm

HM6264ALP-10 -> VCC for data retention : Min 2.0 v
https://www.datasheets360.com/pdf/-5047 ... =105676570 (Page3)
To order: https://fr.aliexpress.com/item/32977382 ... 6c37O8cJcu


HM62256BLP-10 -> VCC for data retention : Min 2.0 v
https://www.datasheets360.com/pdf/90716 ... =105676793 (Page 11)
To order: https://fr.aliexpress.com/item/32978719 ... 6c37O8cJcu

So, I can use "schottky BAT43" for SRAM and Battery.
I see one more on circuit, for SUPER CIC.
Can I use the same "schottky BAT43" ?
Last edited by Kayumba on Thu Jul 16, 2020 4:42 pm, edited 1 time in total.

Kayumba
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Thu Jul 16, 2020 4:12 pm

poorstudenthobbyist wrote:
Thu Jul 16, 2020 3:07 pm
You also should check to see if the data retention or standby current is low as well. The lower it is, the longer your game will save. Generally -L or -LL parts have low currents for save retention.

Coin cell batteries are rated for ~220mAh, so if you divide the amp-hour rating by the retention current, you'll get a rough estimate of how long the battery will last.
Thank you.

One question.
Why to not add some micro "current" controller and use rechargeable battery, so every time that you put in your SNES, it will auto recharge ?

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poorstudenthobbyist
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by poorstudenthobbyist » Thu Jul 16, 2020 4:18 pm

You could, but that requires a battery charge control circuit. More expensive and more complicated. Might as well use non-volatile RAM at that point. I'm also not aware of any rechargable coin cell batteries. They probably exist but I haven't looked.

Besides, with the right SRAM, saves can last up to 20 years anyway.

lidnariq
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by lidnariq » Thu Jul 16, 2020 4:21 pm

poorstudenthobbyist wrote:
Thu Jul 16, 2020 4:18 pm
You could, but that requires a battery charge control circuit. More expensive and more complicated. Might as well use non-volatile RAM at that point. I'm also not aware of any rechargable coin cell batteries. They probably exist but I haven't looked.
LiR2032... but, as you say:
Besides, with the right SRAM, saves can last up to 20 years anyway.
I even have a few games with saves that are well past 20 years and batteries that look full.

I should copy my save games off them, but I can't decide if I quite care.

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poorstudenthobbyist
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by poorstudenthobbyist » Thu Jul 16, 2020 4:30 pm

The only game I really cared about was Pokemon Red, my first Pokemon game. Complete Pokedex with seven level 100 Pokemon.

Not gonna throw away those hundreds of hours! I cut it close though, it took me 21 years to change the battery. I was surprised to find it in tact after not checking for about a decade.

Kayumba
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Thu Jul 16, 2020 4:53 pm

lidnariq wrote:
Thu Jul 16, 2020 4:21 pm
poorstudenthobbyist wrote:
Thu Jul 16, 2020 4:18 pm
You could, but that requires a battery charge control circuit. More expensive and more complicated. Might as well use non-volatile RAM at that point. I'm also not aware of any rechargable coin cell batteries. They probably exist but I haven't looked.
LiR2032... but, as you say:
Besides, with the right SRAM, saves can last up to 20 years anyway.
I even have a few games with saves that are well past 20 years and batteries that look full.

I should copy my save games off them, but I can't decide if I quite care.
20 years!
OMG, In 20 years I will be already close to paradise :D

:?:
So, I can use "schottky BAT43" for SRAM and Battery.
I see one more diode on circuit, for SUPER CIC.
Can I use the same "schottky BAT43" ?

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Re: (SNES)Help With Circuit for LoRom M27C322

Post by lidnariq » Thu Jul 16, 2020 4:54 pm

That's an LED.

Kayumba
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Thu Jul 16, 2020 6:30 pm

lidnariq wrote:
Thu Jul 16, 2020 4:54 pm
That's an LED.
:lol: Ok

Do you know what function do Switch and Jumpers on this schema ?
Its looks like it's just for SUPER CIC, but for what for?

One more question...
If I use LoROM games without SRAM, what will be connections ?
I have some old schema (dont remember where I get this).
Its make connection between "/CART" (SNES pin 49) and "/CE" (pin 11 of EPROM).
I made new jumpers that it will be easy to choose what EPROM to use.
It looks some thing like that, is it right ?
Image

Kayumba
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Fri Jul 17, 2020 11:34 am

please, please... :cry:

LittleRain
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by LittleRain » Fri Jul 17, 2020 2:36 pm

Kayumba wrote:
Thu Jul 16, 2020 8:25 am
2- What is the transistor ? Is it 2N2222 ?
3- Why do you add switch with JUMPERS, what is those fonction ?
Hey no problem at all man, lidnariq answered the other questions, but I'll answer the rest.

2- I am using the S8050, but any NPN will be fine, could also use an N-channel mosfet as well.
3- The jumpers are solder bridges, so if I don't want to mount the switch, I can just solder one of the connections together.

Good luck with your board!

And if you are using the M27C322, I would make an adapter board as well, it is extremely helpful, I made one on my own with perf board and it was pure hell to solder. Next time I order boards I will definitely be ordering one.

Edit: As for adding HiRom capabilities, instead of having 2 decoders, just add solder bridges to the decoders pins. I just whipped this up quickly, I believe it should work.
Hi Rom
Hi Rom
Both Hi and Lo Rom
Both Hi and Lo Rom


And if you don't want SRAM, just remove battery, SRAM and transistor circuit. Do not even need to make a separate board, just don't place those components. Here is a schematic, you can compare with my original.
No SRAM
No SRAM
Last edited by LittleRain on Fri Jul 17, 2020 3:16 pm, edited 1 time in total.

Kayumba
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Fri Jul 17, 2020 3:10 pm

LittleRain wrote:
Fri Jul 17, 2020 2:36 pm
Kayumba wrote:
Thu Jul 16, 2020 8:25 am
2- What is the transistor ? Is it 2N2222 ?
3- Why do you add switch with JUMPERS, what is those fonction ?
Hey no problem at all man, lidnariq answered the other questions, but I'll answer the rest.

2- I am using the S8050, but any NPN will be fine, could also use an N-channel mosfet as well.
3- The jumpers are solder bridges, so if I don't want to mount the switch, I can just solder one of the connections together.

Good luck with your board!

And if you are using the M27C322, I would make an adapter board as well, it is extremely helpful, I made one on my own with perf board and it was pure hell to solder. Next time I order boards I will definitely be ordering one.
Thank you.
But I still dont understand for what for Switch ?
Is it for when you choose to use game with SUPER CIC or NO, yes?

LittleRain
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by LittleRain » Fri Jul 17, 2020 3:19 pm

Kayumba wrote:
Fri Jul 17, 2020 3:10 pm
But I still dont understand for what for Switch ?
Is it for when you choose to use game with SUPER CIC or NO, yes?
I believe it is for pairing with the SuperCIC on the console.
Not sure what pairing does exactly, I think it has something to do with region locking.

Also, I posted another edit for a battery-less version in my previous post.

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Re: (SNES)Help With Circuit for LoRom M27C322

Post by lidnariq » Fri Jul 17, 2020 3:32 pm

Given a supercic lock installed into the SNES, "pair mode" on the supercic key lets the game dynamically switch between 50Hz and 60Hz video modes at run-time. I'm really not clear how one would use that.

LittleRain
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by LittleRain » Fri Jul 17, 2020 3:33 pm

Ahh forgot about that, so yeah basically region differences.

Kayumba
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Re: (SNES)Help With Circuit for LoRom M27C322

Post by Kayumba » Fri Jul 17, 2020 3:56 pm

LittleRain wrote:
Fri Jul 17, 2020 2:36 pm
Kayumba wrote:
Thu Jul 16, 2020 8:25 am
2- What is the transistor ? Is it 2N2222 ?
3- Why do you add switch with JUMPERS, what is those fonction ?
And if you don't want SRAM, just remove battery, SRAM and transistor circuit. Do not even need to make a separate board, just don't place those components. Here is a schematic, you can compare with my original.

LoRom_NoSram.png
Cool. Thank you.

Will try to find some solution to make easily choice if using PCB game with/without SRAM.

What do you think if I will make one bridge for "VCC2" ?
VCC2 will supply : SRAM, Battery, SRAM and transistor circuit from General SNES VCC.
If bridge are connected (soldered), then SRAM, Battery and SRAM transistor circuit are ready to be operating.
By the way, Normally, 74HC139 are in use together with SRAM.
So if nothing are plugged to 74HC139 pins will its woks, or no?
Or I should always put one 74HC139, even when game is without SRAM?
Last edited by Kayumba on Sat Jul 18, 2020 2:52 am, edited 2 times in total.

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