Retroflag NESPi Case - Soft Power & Reset Hack
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@rollerace
The mosfet is basically an electronic power switch, like a relay. Using it allows you to turn off the power switch and have the pi shut down and then cut the power. If you wire the power button directly to the GPIO you can still have the pi shut down but the power LED on the case will remain lit, so you would have to wire it to a gpio as well if you wanted it to turn off without unplugging the PSU. Also, even in shutdown the pi (still connected to the PSU) will continue to draw a nominal amount of current. The diodes are required to make the circuit work, blocking voltage in the required directions to allow the circuit to function the way I needed it to. -
@ortsac
I do not have a schematic drawn up, but I can tell you that the components used were chosen to work together with the Pololu mosfet board. It depends on the additional transistor switch on that board to function as I used it in the case hack. I never really drew up a schematic (although I almost always do) but I simulated the circuit instead based on the schematic provided by pololu. I might be able to draw something up for you though if I find some free time. Wondering why you are wanting to use the power brick instead of the mosfet board though... It's 5 or 6 times the price. -
I just bought this for a build for my niece's xmas gift, and when I saw how well it was made I ordered one for myself... luckily, I was about the last one before that supplier ran out. :D
Didn't know until after about the shutdown/reset issues on these. Seems a rather dumb design that could have been fixed when they came out with the new batch.
Anyways... I'm a NOOB at this stuff, so probably a stupid question I have... but... when I was looking to build an arcade cabinet, I wanted to add a power off switch and it was pretty much just a momentary switch, connected with 2 wires to the Pi and a shutdown script.
Looking at the OP, the MOD has capacitors, resistors, etc... is it more difficult than it needs to be?
Can't the buttons just be bypassed on the board, and wires going direct from the buttons to the GPIO pins? 2 wires for the power, 2 wires for the reset, and add a script?
Again, I'm a NOOB... but, without the case, adding a safe power off button was just 2 wires and a script, I don't recall seeing a tut requiring capacitors and resistors, etc...
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@throbinson said in Retroflag NESPi Case - Soft Power & Reset Hack:
Again, I'm a NOOB... but, without the case, adding a safe power off button was just 2 wires and a script, I don't recall seeing a tut requiring capacitors and resistors, etc...
Really? It's just a question what you are want to do ;)
The solution in this video is just a "standby" shutdown. The Pi and all voltage output (means a external HDD or fan are still powered) If this is enough for you then fine :) -
@throbinson I literally just answered this question only two posts above yours. lol
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Ah I getcha... kind of a standby or sleep mode, not a powered off mode.
Is the OP method the best one? I saw a video on that ETAPrime's YouTube chanel that looked easy enough, but also saw posts saying that it for some reason works for some people, not others.
I don't mind the extra work, and I have a big bin of caps and resistors (started to teach myself simple stuff with DIY's for guitar pedals) I just want to make sure that if there was a 'best' solution out there, that I pick the right one.
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@sabinn I don't see anything you can get from Amazon. Check out Pololu's Canadian distributors. https://www.pololu.com/distributors#Canada
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@throbinson best is in the eye of the beholder. Personally if it was between eta primes hack or mine... Well I'd go with mine. I'm not interested in safe shutdown with the reset button and it's why I went to the trouble of making the hack, I wanted it to function just like the original NES.
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First of all, a big thank you Yahmez for sharing this wonderful power switch solution.
For those of you that can't buy the pololu mini mosfet switch, you can build a simplified version with just a single P-channel power MOSFET (I used a TPC8114) and omit the gate protection zener diode, reverse voltage protection MOSFET as chances of that happening with an usb power supply is fairly minimal. I have done that and built everything on top of the existing power pcb. Functionally, it works the same as the pololu switch board sans the protections. However, be for warned, to build it this way requires good soldering technique and eyesight :P
At the top is any general purpose NPN transistor, MOSFET is square piece on bottom right
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@druz sounds like nice idea. it would be great to see it on a picture ;) dont give up uploading it, maybe try with imgur or something ?
cheers ;) -
@druz said in Retroflag NESPi Case - Soft Power & Reset Hack:
First of all, a big thank you Yahmez for sharing this wonderful power switch solution.
For those of you that can't buy the pololu mini mosfet switch, you can build a simplified version with just a single P-channel MOSFET (I used a TPC8114) and omit the reverse voltage protection as chances of that happening with an usb power supply is fairly minimal. I have done that and built everything on top of the existing power pcb. Functional, it works the same as the pololu switch board. However, be for warned, to build it this way requires good soldering technique and eyesight :P
hmmm.... having trouble uploading an image!!If online somewhere like IMGUR or Photobucket etc... maybe try right clicking it and clicking on 'copy image address'.
I had a few issues with IMGUR in forums and doing that versus using their copy link pop-up worked much better.
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As good as this mod looks... I was wondering if a simpler (fewer parts) method at all?
Having the power/reset work like a real NES is great, but I'd like to have something like the RESET sending a safe power off command, and the POWER shutting the power off/turning on the system.
Would that be a simpler mod? Is that what the ETAPrime mod does? Video shows him pressing the RESET button a few times, but never shows what the POWER button does.
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Hey Guys
hoping you could help me out here, just finished doing the mod and it powers up ok but a few issues
- failed the hardware test, it can power up without the ON cable plugged into the Fan + pin and it will stay on
- fan does not get any power
found the problem
The + pin on the fan was not soldered properly, the board is not double sided -
Still on the fence... ETAPrime vs this... was looking at the Pololu site, and it says to use either item #2810 or #2811... is one better than the other? or makes no difference at all?
Use to be someone on eBay selling kits, shame not anymore... think about $12CAD.
Prob is being in Canada, the part is about $4.50CAD but $20CAD to ship it.
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@throbinson Either one will work fine. There are distributors of pololu in canada... did you check if they have them?
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@throbinson In the 'ETA Prime' version the reset sends a signal to the Pi which then (through a script watching for the signal) initiates a shutdown. The power switch operates as it does in the original case simply hard cutting the power to the Pi.
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@druz That's awesome man! I was originally going to go this route till I found the pololu boards and compared the cost VS the effort required.
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@yahmez said in Retroflag NESPi Case - Soft Power & Reset Hack:
@throbinson Either one will work fine. There are distributors of pololu in canada... did you check if they have them?
Yup... none seem to have them that I could find. One seller was close, had a 2812,2813,2814,2815... but not the 2810 or 2811. :S
ETAPrime I think will work for me... safe shut down, and full power off, pretty much all I need.
I wonder, and sure it can be done... go the ETAPrime route and also add a 3rd button, very small momentary switch, just drill a hole in the case at the back or under the flap and attach to the GPIO as a reset button.
Mostly though just looking for a safe shutdown then full power off... I hope that I won't need to reset very often.
You said you were going this route before seeing cost-vs-effort... which route did you end up going?
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@throbinson Regarding the cost VS effort comment, I was talking about what @druz did (freeforming the components) until I found the pololu board.
Keep in mind, if your looking to safely shut down as simply as possible, you can simply navigate to shutdown in the ES menu and after it completes the shutdown just hit the power button, no mod required for that.
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