Retroflag NESPi Case - Soft Power & Reset Hack
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@daminoutav said in Retroflag NESPi Case - Soft Power & Reset Hack:
Thanks @Yahmez !
I will receive my NesPi case at the end of september and will test that.
If I understand well, when you press Power, it sends an order to Raspberry via GPIO (and we can do what we would like with it, in this case a properly shutdown) and then, hard power off raspberry ? The mofset knows when it have to hard power off via "On Control" => When raspberry is off, GPIO is off then mofset can hard power off ? Am I right ? :)
I'm not sure to understand very well how it works in fact ^^Here is my description of the way it works...
There are three wires connected to the Pi. Two of these are inputs and can sense the state of the switches, one for the power switch (connected through a diode) and one for the reset switch. Both of them utilize the internal pullup GPIO resistors inside the Pi. When you press the power button, it activates the mosfet switch and sends power to the case PCBs and in turn the Pi. As long as the power switch is on, there is power available and the Pi has no way to turn off the mosfet switch. As the Pi boots, it turns on the aforementioned GPIO inputs to read the state of the buttons, it also turns a GPIO pin into an output and makes it go high. This output GPIO is connected to the third wire which acts as a second 'on signal' for the mosfet switch. Attached to this GPIO through a diode, there is a capacitor which upon receiving the 'on signal' from the Pi, charges up. If you hit reset at any point after booting the Pi senses this and initiates a reset of the Pi, but you could have it do anything you like. When you turn off the power switch, the Pi senses this as well and although there is no more 'on signal' coming from the power switch to the mosfet, the Pi's GPIO output keeps the mosfet on. After sensing the power switch is off, the Pi initiates a shut down. As the Pi shuts down the GPIO output goes low... This would mean that the mosfet would shut down instantly if not for the diode and capacitor we attached. Those components keep the mosfet switch on for a few seconds (until the capacitor discharges) to ensure that the Pi is completely shut down safely before switching off.
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@yahmez Thanks that's clear ! So, if I shutdown Rpi directly from Pi and notre button, will it hard power off too ?
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@daminoutav
Not sure I understand your question, but if you initiate a shutdown through ES the Pi will shutdown but the power to the Pi and the LED remain on until you press the power button to switch it off. -
@yahmez oh okay thanks. It's not really like a Mausberry mofset wich allows that :)
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@bug1baby Thanks! Sadly, that mosfet board will not work. The Pololu board has an additional transistor and other components which allow it to work in the way I used it. You might be able to build your own version of the Pololu board though, they do provide a schematic of it on their website. It might be cheaper (but more work) to order the individual components rather than pay that outrageous shipping.
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@bug1baby
Amazon UK has the low voltage one which should work just the same as the one I used. Shipping is bound to be much cheaper.
https://www.amazon.co.uk/MOSFET-Switch-Reverse-Voltage-Protection/dp/B017HY9PIE -
@yahmez Awesome. Thanks for the info
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Hi folks,
I'm new to the RaspberryPi/RetroPie scene and today I've modded my NESPi case according to the awesome tutorial by @Yahmez.
Soldering the wires etc. was no problem but setting up the Pi (a model 3 with the newest RetroPie installed) I got stuck...
SOLVED: Some "expected an indented block" errors in the script caused the problem. So copying the script just from the PDF is not a good idea... :)
Regards
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@Yahmez - For what reason did you go with that mosfet board vs using transistors and resistors along with the capacitor? It looks like you should be able to sub out the board with just the components. I have everything but that mosfet board...
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@doubleeuroz
For simplicity. There are many ways to do this, including using your own board and components whether it is transistors, mosfets, or a relay. For me, a proven $4 board was the easiest and most repeatable solution. The Pololu board is practically made for this application with the two ways to switch it matching perfectly to the pi and power switch combination. Also the form factor was just perfect as well. All in all, it was just the best option for me. -
@snarc
You're not the first having trouble copy/pasting from the PDF. I will be updating the walk through with links to pastebin copies of the code. -
Ok, I am new to all of this and am gathering parts to put together my system, but my question is this: is there a way to use the PowerBlock and the scripts they have for it to do this? Or is it actually easier and simpler to follow @Yahmez guide?
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@cmarquis I have never used a power block so I can not comment as to how it would/could interface to the Retroflag NESPi case. I do know that there is a significant price difference between the two.
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Hardware done, hardware check OK, now I have to add a script into my distrib :)
Edit : Everything is working well :) Thank you @Yahmez ! (note, script into recalbox are already ready for this modification :) nothing to add)
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I have a problem with the script. on my pi at the gpio readall on pin 25 its Mode IN and Value 0. i made all the other things what could be wrong. I tested hardware as you said and it was ok Please Help Someone
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@fernandike download the newest version of the PDF. There is a link to pastebin pastes of the scripts in the updated PDF. Try using that instead of copying from the PDF.
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@daminoutav glad you got it going!
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@yahmez the one that says here? on the PDF?
and wich one its ok the raw or the oder one. by the way i dont know how i fixed that problem on the gpio readall -
@yahmez the guide its awesome. tnx for that. do you have any video showing how it works. i couldnt make it work i tried everithing Visual test ok hardware test ok software test seems to be ok but neither resets or soft shutdown works. it just kills the power right away. and on the hardware test waits a few seconds to shuts off
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