I made a multi-function SNES PCB

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poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

I made a multi-function SNES PCB

Post by poorstudenthobbyist »

I've been working on this one for a while. I don't want this to come off like an advertisement or anything, but I've seen some posts of people showing off their own boards here so I figured it was safe to post.

This board has two EPROM slots and supports SRAM up to 256 Kbit. With the EPROMs, you can make:

1) Single game with one 160/322 ("Single ROM")
2) Single game split between two 160's ("Split 160's")
3) Single game up to 64 Mbit ("ExHiROM")
4) Two games, each on their own 160/322, switching between the two with the reset button, with up to 128 KBit SRAM available to use for each ("Multicart")

Just solder the set of four pads on the back for which of these options to make! I've made a board already with sockets for all the through hole parts so I can test them before placing on a permanent board. Very handy!

Any comments on changes are welcome, as I'll be ordering more boards soon with ENIG finish and want this to be as good as it can be! Though I'm mostly looking for silkscreen changes for clarity since I'm not fond of moving traces or adding parts on a board that's already confirmed working without testing it again :D
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lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: I made a multi-function SNES PCB

Post by lidnariq »

Personally, I'd like to have labels for the various solder jumps so that I can see what's wrong when something's wrong without having to cross-reference to a schematic.

Also, are you dealing with 32K HiROM cart RAM vs 32K LoROM cart RAM? I don't think I see enough solder jumpers for that.
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

The labels are a good idea, but I wonder how legible the silkscreen will be. I'll try it out and see if it's serviceable.

And you're talking about RAM A13/A14 going to A16/A17 for HiROM? Yep, that's accounted for.
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

If you're wondering, the eighteen solder pads on the back breakdown like this:

9 for address lines A15 - BA7
2 for A13/A14 SRAM address lines
4 for SRAM decoder inputs 1A, 1B, 1G, and 2G (2A and 2B are BA5 and BA6 for both)
1 for SRAM decoder output 1Y3
1 for SRAM /CE from the decoder outputs
1 for /OE on the databus multiplexers
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: I made a multi-function SNES PCB

Post by Kayumba »

Great job!
I like it.

Can you tell me what size of track width do you setup ?
I trying to make Autorouter with EasyEDA, it's make me mad... :cry:
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

Depends on the board, and I also tend to make the power traces a bit thicker than the others. But I normally just stick to something a bit bigger than whatever the manufacturer can guarantee. You don't want to hit their minimum.

https://electronics.stackexchange.com/q ... ace-widths
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: I made a multi-function SNES PCB

Post by Kayumba »

poorstudenthobbyist wrote: Thu Jul 30, 2020 9:14 pm Depends on the board, and I also tend to make the power traces a bit thicker than the others. But I normally just stick to something a bit bigger than whatever the manufacturer can guarantee. You don't want to hit their minimum.

https://electronics.stackexchange.com/q ... ace-widths
So the width are to determine according with current.
What is max current that flow in SNES PCB cartridge ?
If I will respect the MAX current, it's the more important , no?
And for all the other tracks it should works also.
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

Probably a few milliamps at most. That's not going to be your main concern.
lidnariq
Posts: 11432
Joined: Sun Apr 13, 2008 11:12 am

Re: I made a multi-function SNES PCB

Post by lidnariq »

Individual signal traces can probably go all the way down to 6 thou, but you should use wider to improve yield of PCB fab. Power traces should be calculated based on the peak current possibly drawn by all parts on the board. And you should use a ground pour.
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

Didn't wanna make a new thread, but I've updated this board for through-hole components, as well as expanding the SRAM size to 1024 Kbit. I made the design a lot simpler - fewer solder pads.

Another board I made has a socket with the original Mask ROM pinout, as well as solder pads to change them to accomodate (swapbinned) 27C801s. This board also includes sockets for 27C160s. The purpose of this board was to offer something a bit simpler without having to use multiplexers and 27C322s, in order to cut down on costs of making smaller games, as well as offer a replacement board for original games that are damaged in some way but still have functional ROM chips and/or CICs to be used.

I wrote guides for each of these boards, denoted as "Basic" and "Advanced", and if anyone would like to check them out and let me know if they're easy enough to follow and understand, I wouldn't be upset about it ;)

Basic board: https://thepoorstudenthobbyist.com/2019 ... ick-guide/
Advanced board: https://thepoorstudenthobbyist.com/2020 ... ard-guide/

Basic Board Front
snes_basic_1.jpg
Basic Board Back
snes_basic_2.jpg
Advanced Board Front
322_multi_front_new.jpg
Advanced Board Back
322_multi_back_new.jpg
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: I made a multi-function SNES PCB

Post by Kayumba »

Hi poorstudenthobbyist,
Nice job !

Can I ask you about 1024Kbit SRAM.
Can you tell me please where are connected listed pins :
"CS2" and "NC"

I looking for to make PCB with FRAM chip.
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

Here's the truth table for the 1024K SRAM
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Screenshot_20210428-152543.png
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: I made a multi-function SNES PCB

Post by Kayumba »

poorstudenthobbyist wrote: Wed Apr 28, 2021 12:27 pm Here's the truth table for the 1024K SRAM
Thank's.
Still try to lear how to read it :roll:
FInd here pinout for 1024 :
https://wiki.nesdev.com/w/index.php/6264_static_RAM

Code: Select all

           .----\/----.
      nc - |01      32| - +5V
     A16 - |02      31| - A15
     A14 - |03      30| - CS2
     A12 - |04      29| - /WE
      A7 - |05      28| - A13
      A6 - |06      27| - A8      
      A5 - |07      26| - A9      
      A4 - |08      25| - A11       
      A3 - |09      24| - /OE       
      A2 - |10      23| - A10       
      A1 - |11      22| - /CS1    
      A0 - |12      21| - D7      
      D0 - |13      20| - D6      
      D1 - |14      19| - D5      
      D2 - |15      18| - D4      
     GND - |16      17| - D3      
           `----------'
"when /CS1 is low and CS2 is high, the chip is selected and will accept input or provide output to the data bus."
Really confuse about LOW and HIGH.

If I understand right,
symbole "/" means LOW ?
/CS1 = LOW
CS2 = HIGH (cause without "/"), yes ?

When it says LOW, how its have to be connected ? To GND or leave it like "not connected" ?
And same for HIGH ? Should it be connected to VCC ?
poorstudenthobbyist
Posts: 252
Joined: Fri Jun 24, 2016 4:20 pm

Re: I made a multi-function SNES PCB

Post by poorstudenthobbyist »

Low and high just indicates voltage levels: LOW = GND, HIGH = VCC
Kayumba
Posts: 246
Joined: Sun Mar 01, 2020 2:36 am

Re: I made a multi-function SNES PCB

Post by Kayumba »

poorstudenthobbyist wrote: Wed Apr 28, 2021 3:17 pm Low and high just indicates voltage levels: LOW = GND, HIGH = VCC
Great !
I see better now.
And "RESET" pin is HIGH when normal gameplay, cause held to VCC . :D

Last question,
Do 1024 change some pinout address for LoROM or HiROM ?
I can't find any info about that.
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