Sunday, 12 October 2014

Raspberry Pi NES - Complete!

It's taken a surprisingly long time to polish this project off. Although initially all seemed well I had endless problems with the power switch. I was getting crashes, premature shutdowns, and other issues that seemed to increase in frequency as time went by. For a long time I thought I must have needed better quality USB cables so I kept trying different cables, but that didn't make a difference, and eventually I realised the only possible explanation was the power switch circuit. I bought a second switch circuit from Mausberry Circuits and they were nice enough to include two switches in my order to make up for the broken one, but before it arrived I also purchased a different switch circuit from LowPowerLab called ATXRaspi (http://lowpowerlab.com/atxraspi/). This is a really great circuit, it works similarly to the Mausberry one but only works with a momentary switch and has some extra features.

New power switch

First I had to change the NES power button from a toggle switch to a momentary switch. This is really easy, as you can see in the picture below there is a small copper coloured metal plate and wire on top of the power switch housing (just behind the spring).  These can be easily pulled out, and they can be removed without damaging them, so this is not an irreversible modification.  I didn't know this would be the case so I actually bought a spare NES power/reset button assembly and modified that.


The ATXRaspi is larger than the Mausberry circuit and it has connections coming in from 3 sides, so it takes up significantly more space so I mounted another piece of acrylic to screw it to.




The ATXRaspi has some nice features.  Press the button once to boot up, to shut down hold it down for a few seconds.  You can also connect the NES LED to it and this gives you a bit more feedback; The LED starts to pulse when it starts shutting down and then pulses even more rapidly when it's finished shutting down and before it cuts power completely. Also if your Pi crashes you can hold the button down for 10 seconds (I think) and it will hard reset. I haven't had it crash yet so I haven't tested this but in theory it's a nice feature to have.  I highly recomment this product, it's really great, and the guy who sells them is extremely responsive and helpful via email (Thanks Felix!).

I must confess that having the button as a momentary switch instead of a toggle does bother me slightly as it's less authentic, but it's a minor thing. I do now have the replacement switch from Mausberry Circuits but setting it up requires soldering and I need to replace the tip on my iron because it's not tinning properly at the moment making it a nightmare to use. At the moment I Just want to screw the NES case closed and enjoy the games, but I'll rig up the other switch at some point and then decide which one I want to use.  Doesn't hurt to have different switches, I'm sure I'll come up with other Raspberry Pi projects to do.

Cartridge slot facade

One last little touch I wanted to do was to clean up the cartridge slot so that it didn't looks so amateur. To do this I just cut a piece of black plastic (cut from the cover of one of my uni notebooks) and hot glued it in place.  The cutout around the hub is a little rough if you look closely as my stanley knife is blunt as hell right now, but it's still a massive improvement.



Big improvement.


So that's it, the project is done.  Now back to Punch-Out!!


6 comments:

  1. Hey, I'm about to being doing this same project. Can you show me a picture of the wiring from the Power button to the ATXRaspi? The project is pretty straight forward for me but I want to make sure I have the wires soldered correctly.

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    1. http://oi57.tinypic.com/okbce0.jpg

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    2. Actually that diagram isn't quite correct. The order in which the 5 coloured wires are coming off the power/reset switch assembly should be in reverse order. However which colour connects to which pin on the ATXRaspi is correct, so if you go by the colours you'll be fine. I'll post a full wiring diagram (at some point) where everything is correct, if you need further clarification before then you can ask.

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  2. Sure, I can do that. I'll whip up a diagram later today when I have some time. That said, if I were you I wouldn't solder any wires to the ATXraspi, it has header pins so I recommend you use connectors on all your wires - that way they can be reconfigured for future modifications and also in case of a mistake.

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  3. Do you still need a capacitor for the LED since you switched to the ATXRaspi?

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    1. Oh good question. I'm pretty sure that I did in fact remove the resistors, and that they aren't necessary when using the ATXraspi. I can't be 100% certain without opening up the NES, but when I look back through my photographs on this blog it does look like a different wire connecting to the LED after switching to the ATXraspi, so I'm pretty confident. Another thing you can do is have a look at the ATXraspi website and see if they have any info, if not, the guy that makes them is very responsive to email in my experience.

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