(S)NES GPIO-Gamepad Adapter with Protection Circuitry


11 posts
by petrockblog » Sat Sep 01, 2012 11:36 am
Hi everyone,

I am currently designing a PCB that should be used for connecting NES and SNES connectors to the GPIOs. The connectors, in turn, will be used for connecting NES or SNES gamepads. From the ouside it will look like this:
Image
The PCB is supposed to replace the board that I used in >>this<< work. There the PCB really just replaced some wires.

The new PCB should contain some GPIO protection circuitry. Furthermore a momentary switch should be soldered onto the board. The controllers are driven with 3.3V and can be polled with just three data lines each. I used the Zener diode protection as explained >>here<< and my current PCB design of the new board looks like this:
Image

I am not sure about some things here:
  • Would you say that it is necessary for this application to have a protection for the GND and VCC pins as well? If so, what would you propose?
  • Is this an appropriate protection for the case in which the controllers are disconnected while the RPi in switched on ("transients protection")?

Thank you!
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by TonyD » Sat Sep 01, 2012 2:52 pm
You could put a small resettable fuse say 100mA such as a Bourns Multifuse (p/n MF-R010) on the supply rail to handle any over currents. If you're worried about transients then you could use a buffer IC such as a 74HC125 on the clock and data signals.
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by petrockblog » Sun Sep 02, 2012 8:18 pm
TonyD wrote:You could put a small resettable fuse say 100mA such as a Bourns Multifuse (p/n MF-R010) on the supply rail to handle any over currents. If you're worried about transients then you could use a buffer IC such as a 74HC125 on the clock and data signals.

Thanks a lot for your suggestions! I have ordered the components and will assemble a prototype next.
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by gordon@drogon.net » Mon Sep 03, 2012 5:51 pm
petrockblog wrote:Hi everyone,

I am not sure about some things here:
  • Would you say that it is necessary for this application to have a protection for the GND and VCC pins as well? If so, what would you propose?
  • Is this an appropriate protection for the case in which the controllers are disconnected while the RPi in switched on ("transients protection")?

Thank you!


Looks good, but I don't recognise the connectors on it - the NES controllers I have had a fully lop-sided D type of plug on them..

However, personally, I think the need for protection like that is a little OTT :) I'm pretty sure you'd not find anything like it on a real NES console!

... Maybe I just like living on the edge though, but I don't think I am. Connecting up a NES controller shouldn't any different from connecting anything more than switches & LEDs to the Game Port IO connector on the Pi.

At least I never bothered when I did this:

[link]https://projects.drogon.net/nes-controller-on-the-raspberry-pi/[/link]

Hm. Must get round to writing more games for it!

-Gordon
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by DexOS » Mon Sep 03, 2012 6:50 pm
gordon@drogon.net wrote:Looks good, but I don't recognise the connectors on it - the NES controllers I have had a fully lop-sided D type of plug on them..

However, personally, I think the need for protection like that is a little OTT :) I'm pretty sure you'd not find anything like it on a real NES console!

... Maybe I just like living on the edge though, but I don't think I am. Connecting up a NES controller shouldn't any different from connecting anything more than switches & LEDs to the Game Port IO connector on the Pi.

At least I never bothered when I did this:

[link]https://projects.drogon.net/nes-controller-on-the-raspberry-pi/[/link]

Hm. Must get round to writing more games for it!

-Gordon

Thanks Gordon, thats a nice write up, i have about 6 NES controllers from a project that fell though.
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by gordon@drogon.net » Mon Sep 03, 2012 8:26 pm
gordon@drogon.net wrote:[link]https://projects.drogon.net/nes-controller-on-the-raspberry-pi/[/link]


Bother. Used the wrong tags and didn't get back in-time to edit it!

https://projects.drogon.net/nes-controller-on-the-raspberry-pi

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by TonyD » Tue Sep 04, 2012 1:33 pm
gordon@drogon.net wrote:Looks good, but I don't recognise the connectors on it - the NES controllers I have had a fully lop-sided D type of plug on them..

The connectors are from a nintendo SNES. I've used them before when building a Uzebox retro-minimalist video game console. I used to harvest them from SNES controller expander units from ebay.
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by petrockblog » Tue Sep 04, 2012 2:02 pm
TonyD wrote:The connectors are from a nintendo SNES. I used to harvest them from SNES controller expander units from ebay.


That's where I got these from as well :-)
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by petrockblog » Tue Oct 02, 2012 6:13 am
I have ordered the PCBs of the newly designed (S)NES GPIO adapter and will get them at the end of next week. Besides a multifuse and a line driver as protection circuit it contains also a momentary switch that can be used, e.g., as a reset or shut down button.

As soon as I have assembled the first adapter I will post an article about in in my blog and also announce it here.
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by petrockblog » Sun Oct 21, 2012 3:49 pm
It is finally done. If you are interested in connecting NES or SNES controllers o the RPi GPIO pins you might want to have a look at the RetroPie GPIO Adapter!
Image
It is a dedicated GPIO adapter for the Raspberry Pi that allows an easy and safe connection of up to two NES or SNES controllers.
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by TonyD » Sun Oct 21, 2012 8:37 pm
nice :-)
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