Shared Projects by ziggy587

This is a SNES cart PCB that can be used for LoROM or HiROM games with a max ROM size of 16 Mb. It can be used for either a single game, or with the 74'161 installed it can be used as an X-in-1 multi cart. Games are switched by resetting the console.

I have tested this board with a 16 Mb HiROM game on a 29F160, as well as 2-in-1 LoROM games (2 x 4 Mb games) on a 29F800, and everything is working correctly. I will add instructions and a BOM when I get the chance. Until then, pretty much everything is self explanatory.

The jumpers for the four address lines (A20, A19, A18 and A17) control the X-in-1 multi game function. If you close pads 1 and 2 then that address line is controlled by the SNES. If you close pads 2 and 3 then that address is controlled by the 161. If you’re putting a single game on the cart, then close pads 1 and 2 for all four of them.

The placement of the TSOP will interfere with the cart shell support post. While it will fit as is, that post will be putting pressure on the TSOP which may eventually lead to damage. I recommend breaking that post off to avoid any possible issues. A new revision of this PCB is coming soon, and the TSOP will be moved so that it no longer interferes with the support post.

This board has been tested and found to work as expected.

There is a surface mount version available as well.

Description

You can use this PCB as a basic LoROM board with a max ROM size of 8Mib. Or, with the 74LS161 installed, you can use this board as a 2-in-1 or 4-in-1 multi cart. Games are switched by hitting the console reset button. This board was designed to use 27C080/27C801, but you can use other memory with a compatible pinout such as 27C040/27C401.

Jumper Settings

Jumpers JP1 and JP2 will have to be set depending on how many games will be on the cart and what size memory you are using. View the tables below to see how to set the jumpers when using 29C080 or 29C040 memory.

For example, “1-2” means to short pads 1 and 2.

JP1 controls ROM A19 and JP2 controls ROM A18. Other configurations can be made by using jumper wires.

Note on using 27C040 memory: 27C040 does not have an A19 address line, which is why JP1 is unused in this case. The highest address line on 27C040 is A18. If you close close the 2-3 pads on JP2 that will allow for a 2-in-1 (two 2Mib games), however, the games will be switched every other reset. If you want to use 27C040 and have the games switched on every reset, solder a bodge wire from JP1 pad 3 to JP2 pad 2. This will connect the highest address of 27C040 (A18) to the first output of the 161.

BOM

Notes

Use the SuperCIC key, found here. If your SNES is modified to deactivate the lockout chip, then you can omit this part if you wish. If you do not use the Super CIC, then omit C4 and R2. R2 is a pull-up resistor, the value isn’t crucial, anything 2.5 k (2k5) or higher should be fine.

If you are only installing one game on the cart, then you do not need the 74LS161 or C3. In this case, set both jumpers to the 1-2 position.

R1 value is determined by the LED that you use. Digi-Key has a calculator to make it easy. If you do not use an LED than omit R1.

JP3 controls the LED. If you bridge the left and middle pads, the PIC will control the LED. If you bridge the right and middle pads, the LED will have constant power. If you are not using using an LED then you can ignore JP3.

JP`1 and JP2 jumper pads are spaced for 0 ohm 0805 resistors, but you can simply use a blob of solder instead. Alternatively, you can use a bit of wire or the trimmed legs from C1.

DO NOT order this board with OSH Park’s standard 1.6mm board thickness. 1.6mm is too thick and you wont be able to insert the cart in the console (you will likely damage your cart slot if you somehow manage). You can get 0.8mm from OSH Park, and it should work fine, but please keep in mind that this is thinner than official SNES carts and may not always work properly. The correct board thickness for SNES carts should be 1.2mm, which sadly OSH Park does not currently offer.

Version History

Rev.B V2

• Added JP3 (select if LED is controlled by PIC or has constant power). • Added more ground plane area to front side. • Added silkscreen edge connector identifiers.

Rev.B

• Moved IC2 and C3 further from edge connector; amended related traces. • Improved various trace and via placements; reduced via count. • Moved location of C2; adjusted GND and +5V planes. • Fixed JP2 mislabeled silkscreen.

New version here: https://oshpark.com/shared_projects/s4x1yCHV

Tested with Framemeister and found to be working. I’ve read that this is also compatible with the OSSC.

http://dcemulation.org/?title=Dreamcast_480p_XRGB-mini_Framemeister_Cable

All the info you need is in the above link. The only additions I made are C6 decoupling capacitor (0.1µF) and JP1 (wire to SPST switch to select between 240p/480i and 480p modes). You can jump pin 6 inside the AV connector if that’s easier (one less conductor needed). You could also omit pin 7 or connect it to ground inside of the AV connector if you don’t care to switch between resolution modes.

Stereo to Mono Audio Adapter

Note, the web address on the PCB is no longer valid. The article that this is based off of has moved and can be found at the following address.

https://www.ranecommercial.com/legacy/note109.html

See Figure 2 from the above link. This takes a stereo audio signal and sums it to a mono output. Read the above linked page for more info.

TRS = Tip, Ring, Sleeve. T is the LEFT channel and R is the RIGHT channel (although it really doesn’t matter since you’re summing them). S is GROUND. All resistors are 0805 size. Use either mono output, they are both the same (or use both for a dual mono output).

R1/R2: 475 ohm, 1% tolerance R3: 20 k ohm, 1% tolerance

Use shielded cable for inputs/outputs for best results.