NESPi case, trying to hack in a Mausberry, may have destroyed it, help!

cyperghost

@DIY_glenn
Just plug it in and see what happens :)
I think it should work.... but nice idea ;)
If you are able to get the reset pad working by connecting GRND and (+) then it's okay ;)

caver01

@diy_glenn Oh, I see now. You think that resistor is connected with a trace back up from the reset pin hole. It does look that way.

DIY_glenn

@caver01 Exactly. It definitely is, I can see the trace from the side of the PCB where I made the cut. I just can't see exactly where it goes. But I'm pretty sure it goes to ground. I'll measure tomorrow when I have my multimeter.

The other thing is that I'll probably not be able to do what I marked in red, that hole is too small! But I could maybe trace out which pin it goes to on that chip, and solder between that and the resistor. Otherwise from the correct chip pin to any ground (f.ex. "RST -").

I'm not that good with electronics, but from what I can see, and what would make sense to be connected to "RST +", would be a pull-down resistor to avoid a floating pin...

caver01

@diy_glenn since it is already a "loss", you could try scraping the enamel off of the entire diagonal trace on the back side. With no components in the way, you might get a good solder if you lay a wire along that line. The wire could be routed up through the "airhole" above the yellow cap.

jmcfsu13

I would think to remove the half of the screw hole before the PCB...

day

Hi DIY_glenn,

I have a the same NESPi case AND the same Mausberry PCB as you, but I gotta say I cant find a way to wire them, so I was wondering, could you please provide a wiring diagram or quick tuto, or even better, a quick and dirty paint picture on how to wire it to the rest of the case ?

That would really be amazing to share it here please !

Thanks for your help.
Best,
day

jmcfsu13

@day https://retropie.org.uk/forum/topic/13361/yet-annother-retroflag-nespi-case-with-mausberry-softshutdown-duo-led-momentary-switches/21

day

@jmcfsu13 thanks for your answer however I am not sure I understand how to do the wiring. The post you linked seems to be more of a measuring voltage guide, even if I don't get the part where it seems I should give an 'impulse' to the pi?

cyperghost

@day The wiring should be clear but in fact the post here is more a technical how to perform a shutdown via GPIO signal. It's not a guide of measuring voltage ... it's a guide what will happen if you do so :)

I don't get the part where it seems I should give an 'impulse' to the pi?

If you use a momentary switch you give an impulse to mausberry and via gpio the pi can also give an impulse back.

But back to your question:
What's your mausberry version? Is there a switch already installed?
Can you provide a picture or shema of yours?

day

@cyperghost I have the same mausberry PCB as mentionned in this thread. And have the retroflag NESPi case which switches I wish to use.

I have no idea how to wire the mausberry PCB to the case so that I case use the switches.

I tried wiring the red and black wires that went to the micro USB PCB from the case (the one OP removed, and did as well) to the SW + and - of mausberry PCB. Then I connected the blue and white pins to the gpio23 and 24, then I wired the 2spring green connector 5v and gnd to the pi3.

Then I plugged the RJ45 and USB extension from the case to the pi3.
I added a fan and the on button would work, fan would turn. Pi3 doesn't turn on however, neither off and reset button.

So here I am :)

cyperghost

@day You have to cut the traces to the switches or do it like I've done

day

@cyperghost I am not 100% sure of what you did exactly since I do not clearly see on the picture where the wires go to...
also, I do not whish to have the duoled. do you have a simple wiring diagram somewhere ? or maybe explain the "cut the traces" approach along with the correct diagram for that option ? I would be grateful.

Best,
day

caver01

@cyperghost I am thinking I need to get one of these cases for my next project, but I don't see why you'd have to cut any traces or even replace the power PCB. Can't you simply follow the traces to the built-in header block and add your wiring there instead of using the stock plugs? Seems like even the Mausberry circuit could nestle in next to the existing power board and you could just run the power wires over to it or solder on a micro USB plug. Maybe the space constrains are too tight? I think I would have to give it a try.

lostless

@day

Cut these traces that are circled. That isolates the switches and LED.

This is how I wired mine up. I hope these help to understand how to hook it up

jmcfsu13

@day sorry I meant to post to the thread not a specific post. If you go to the beginning of the thread there is more info

jmcfsu13

@lostless what size resistors did you use?

lostless

@jmcfsu13 I used a 200ohm resistor on the LED. A basic red LED drops 1.7 - 2.0 volts and max current of 18-20mA. So giving it 3.3V minus the 1.7 leaves 1.6 volts to be used by the resistor.. We want 18mA max. In don’t know the specs of this individual led. So ohms law. 1.6/0.018 = 88.8 ohms. So 100ohms is the closest and an extra 100 to lower brightness a tad if even noticeable.. LED don’t dim in a lineier fashion and i’ve ran them in the microamps with it still being visible.

jmcfsu13

@lostless cool, can you explain the two resistors on the reset button and how you came to those values? You seem to really know your stuff.

lostless

@jmcfsu13 it’s just a voltage divider. The 2 are a 10k ohm and 1k ohm. It’s 10k from 3.3v to gpio and one side of switch. 1k from other side of switch to ground. With the reset open, the 10k really does nothing. It does help lower the current going to the gpio pin. But it’s virtually 0 if set up right. From what I undersatnd, Gpio pins are basically look like and open circuit when set as a input with pull up tuned on. It’s just measuring what voltage there is on the pin. That’s it. So with the switch open, it just reads 3.3 ish volts. A high. When the reset is pushed the 3.3 v now has a route to ground through the second resistor. From there the gpio is measuring the voltage from ground across the 1k. Since the 10k is ten times greater than 1k. So the 10k drops 10 times more voltage than the 1k.
Formula 3.3v = x + 10x. X being the voltage at the 1k
So the point between the Two resistors is 0.3v. The pi low point triggers around 1.1v. So the pin reads low. The large nubers are there just to keep current down. Ohms law again. 3.3/(10k+1k)= 0.3mA or 300 microamps, is pulled when the button is pressed. Gpio cares nothing about current as an input.

Ohms law
E=I*R
E measured in volts
I measured in amps
R measured in ohms

day

@lostless thanks a lot for these pictures and explanation. Helps a lot. Will give it a try tonight. Quick qsts however, I don't see the 'reset resistors' you just explained, in fact I don't see the reset switch wired to anything and nothing from RST on mausberry PCB, why? Also, I should cut something in the PCB that is top right in the second picture, right? And finally, white and blue wires from mausberry goes to gpio23 and 24 of pi without resistors, right?

Best,
day