(SNES)Help With Circuit for LoRom M27C322
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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: (SNES)Help With Circuit for LoRom M27C322
Oh. I use an ICD3, but I know of people using PICKITs.
(In fact, it has to be programmed using HV programming: it uses /MCLR as a general purpose input.)
(In fact, it has to be programmed using HV programming: it uses /MCLR as a general purpose input.)
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Re: (SNES)Help With Circuit for LoRom M27C322
Ahh, lucky I asked, would not have realized that till its too late.
I guess ill stick with the 629 for now, my parallel programmer can't program that chip.
I'm currently designing a truly Universal programmer on the side, guess I'll wait until then.
Edit: Now that I think of it, I may be able to program it, and then set MCLR as IO. Which the programmer would then disconnect and never be able to be used again. I'll do that next revision though, I got a bunch of spare 629's anyways. I'll test with an 629 as well, as I can always unbrick it with my uni programmer.
I guess ill stick with the 629 for now, my parallel programmer can't program that chip.
I'm currently designing a truly Universal programmer on the side, guess I'll wait until then.
Edit: Now that I think of it, I may be able to program it, and then set MCLR as IO. Which the programmer would then disconnect and never be able to be used again. I'll do that next revision though, I got a bunch of spare 629's anyways. I'll test with an 629 as well, as I can always unbrick it with my uni programmer.
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Re: (SNES)Help With Circuit for LoRom M27C322
Battery will not work on that with most SRAM chips.
Use this one instead, I haven't tested the new battery circuit, but its the same one that the PoorStudent uses so there should be no problems.
Use this one instead, I haven't tested the new battery circuit, but its the same one that the PoorStudent uses so there should be no problems.
Re: (SNES)Help With Circuit for LoRom M27C322
OMG!LittleRain wrote: ↑Sun Jul 12, 2020 4:42 pmBattery will not work on that with most SRAM chips.
Use this one instead, I haven't tested the new battery circuit, but its the same one that the PoorStudent uses so there should be no problems.
snes_32mb_lorom.png
Thank you man !!!!!





Will try to combine it and add HiRom EPROM and 27C160 EPROM pins.
PS:
1- What DIODES do you use ? Will it work with DIODE-1N4148 ?
2- What is the transistor ? Is it 2N2222 ?
3- Why do you add switch with JUMPERS, what is those fonction ?
4- Where do I have to connect this Battery Net Port ?

It should be VCC (SNES), but across diode like here:

I dont see this diode on your schema.
Or maybe it's should make contact like that?

I maybe do some mistake, but I think, if you follow diagram of poorstudenthobbyist, it should be like that, no?


Re: (SNES)Help With Circuit for LoRom M27C322
Low forward-voltage schottky diodes are better. It may work with 1N4148s, but you may also randomly lose the RAM contents.
No-where. Vbat is a test point.4- Where do I have to connect this Battery Net Port ?
No, the node you're looking for is "Vcc/2" which is already connected.Or maybe it's should make contact like that?
Doesn't matter. Current flows through both the resistor and diode, or flows through neither.I maybe do some mistake, but I think, if you follow diagram of poorstudenthobbyist, it should be like that, no?
Re: (SNES)Help With Circuit for LoRom M27C322
Thank you lidnariqlidnariq wrote: ↑Thu Jul 16, 2020 11:51 amLow forward-voltage schottky diodes are better. It may work with 1N4148s, but you may also randomly lose the RAM contents.No-where. Vbat is a test point.4- Where do I have to connect this Battery Net Port ?
No, the node you're looking for is "Vcc/2" which is already connected.Or maybe it's should make contact like that?
Doesn't matter. Current flows through both the resistor and diode, or flows through neither.I maybe do some mistake, but I think, if you follow diagram of poorstudenthobbyist, it should be like that, no?
Can you give me link for reference, please.Low forward-voltage schottky diodes are better.

I have at home only :
1N4001
1N4148
1N4007
Not sure if I can use one of them, without damage or loose some contents.
Re: (SNES)Help With Circuit for LoRom M27C322
4001 and 4007 are even worse, with higher forward voltages. Won't damage anything, just may lose your saves.
Something like the BAT43 or BAT54 diodes are a reasonable place to start, but just search your favorite electronics supplier for "schottky diode".
Something like the BAT43 or BAT54 diodes are a reasonable place to start, but just search your favorite electronics supplier for "schottky diode".
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Re: (SNES)Help With Circuit for LoRom M27C322
I've used 1N914s without issue for a while, which are pretty similar to 1N4148s. The current required to supply the SRAM data retention isn't too high (assuming you pick the right SRAM) so your forward voltage will be low.
That said, schottky diodes are generally better.
That said, schottky diodes are generally better.
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Re: (SNES)Help With Circuit for LoRom M27C322

Found BAT43 !
https://fr.aliexpress.com/item/3285411 ... eb201603_!
BAT54, all what I found is SOT23

Re: (SNES)Help With Circuit for LoRom M27C322
Ok.poorstudenthobbyist wrote: ↑Thu Jul 16, 2020 12:48 pmI've used 1N914s without issue for a while, which are pretty similar to 1N4148s. The current required to supply the SRAM data retention isn't too high (assuming you pick the right SRAM) so your forward voltage will be low.
That said, schottky diodes are generally better.
So...schottky BAT43 !
They are pretty cool. I like the color.

I'am surprise cause schottky BAT43 it's 30V (Peak voltage), is that LOW ?!
1N914s -> 100V (Peak voltage)
1N4148s -> 100V (Peak voltage)
All kind of SRAM that I have is OK :poorstudenthobbyist wrote: ↑Thu Jul 16, 2020 12:48 pmThe current required to supply the SRAM data retention isn't too high (assuming you pick the right SRAM) so your forward voltage will be low.
BR6216B 10LL -> Single +5 V supply
HM6264ALP-10 -> Single +5 V supply
HM62256BLP-10 -> -0,5 to 7,0 V supply
Re: (SNES)Help With Circuit for LoRom M27C322
Not really. They're specifically designed for low forward voltages, and the reverse voltage isn't a parameter that they care about. In this case, they shouldn't be seeing more than 5V reverse voltage anyway.
For this purpose, what you care about is the line in the datasheet that says "minimum voltage for retention", not the operating voltage.All kind of SRAM that I have is OK :
Re: (SNES)Help With Circuit for LoRom M27C322
I dont find that."minimum voltage for retention"
"Standby Voltage-Min" Is that the same?
Or "Supply Voltage-Min (Vsup)"
If in datasheet I dont find "minimum voltage for retention", that’s mean that they does not have a separate RAM retention voltage.
So in this case, the minimum voltage for RAM retention is the normal minimum Vcc voltage, exact?
BR6216B 10LL -> Supply Voltage-Min (Vsup) : 4,5
HM6264ALP-10 -> Min Supply voltage : 4.5
HM62256BLP-10 -> Min Supply voltage : 4.5
Re: (SNES)Help With Circuit for LoRom M27C322
Yes, probably.
For both Hitachi parts, look at the page "Low Vcc Data Retention", where the line is given:HM6264ALP-10 -> Min Supply voltage : 4.5
"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.
- poorstudenthobbyist
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Re: (SNES)Help With Circuit for LoRom M27C322
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.
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.
Check out my website for NES, SNES, and Genesis tutorials here. And visit my store for some custom tools and boards for making games here.
You can also follow me on Twitter for infrequent updates and bad jokes!
You can also follow me on Twitter for infrequent updates and bad jokes!