How-to: Picade 12" Screen + HAT + Single Power Source + On/Off Buttons!


#101

Hi

Sorry to hear that.

The only thing I can think of is to solder the connections.

Cheers

Paul


#102

Cheers Paul,

Yeah I think that is the only thing left! I have got slightly improved results by swapping out some larger wires for stock shorter ones (such as audio and pi to Picade) perhaps there was some resistance in the system. I now only get the lightening strike if I SSH via wifi whilst playing a game, perhaps that is just something I can live with. I’ll test it on Ethernet also to see if it is just the wifi. Assuming it’s not an issue with the pi itself :)?! I guess as long as I don’t get it during usual gameplay that’s fine.

If I did decide to solder the converter can I solder direct the the ATXraspi +/- connections or best to use jumper pins/molex?

Cheers!


#103

Ok final update for the night! I have managed to eradicate the lightening strike completely, even during SSH file transfer, by finding optimal settings.

I had a little mini 5v fan attached to the pi GPIO pins, I had also overdriven the volume to around 85-90% (I noticed when I maxed my volume I was also getting the strike). So if I leave the volume around 70%, disconnect the mini fan and have no overclock at all then I get no strike!! Maybe all those things were just pulling too much power. Do you have your vol overdriven to above 70-80%?

I’ll try to DuPont onto the ATXraspi at some point to see if that gives me a bit more power but for now I think we are sorted. I had wanted to add some LED 5v buttons but given I’m so tight on power am a little concerned around that. What do you think?

Cheers!


#104

Hi Paul,

I had a thought on this, would it be possible to add another step down converter and dedicate one directly into the pi and one directly into the ATXraspi? Do you know how many amps the ATXraspi draws?

Cheers!


#105

Hi

The Pi must be supplied by the ATXRasPi in order for the shutdown / power off to work.

You could add a second voltage converter to power your button LEDs separately but you may be close to the 5A supplied by your power supply already.

I have the volume on the Pi set to 100% and then control the volume via the buttons on the side of the Picade. I did once ramp the Picade up to full volume without seeing the under voltage indicator but it was far too loud so didn’t leave it like that.

Personally I would use a connector on the ATXRasPi rather than soldering directly. You can get a DC power socket that will fit the PCB and then solder a DC power plug to the wires from the converter if you don’t want to use the Molex connectors I used as they can be fiddly to put together.

Socket

Plug

Cheers

Paul


#106

Cheers Paul,

Good point on the ATX piece I did think about that after I posted. So looks like either the DC in or molex connectors are the way to go to see if I can once and for all get rid of this lightening strike :)! It does come on for me if I put my volume up to 100 and turn it right up. Do I need any special tools to fit the molex connector?

Interestingly i did take a look on the ATXraspi website and found this:

https://lowpowerlab.com/guide/atxraspi/load-tests/

So it does seem to be a bit of a known issue particularly during boot up.

Cheers!


#107

Hi

Ideally you need to buy the correct crimping tool for the molex connectors but as you are only doing a couple its probably not worth it.

Something like this

I used a pair of pliers to crimp the wire and then soldered the wire into the crimp as just crimping with the pliers led to the under voltage symbol appearing.

That is an interesting link.

Personally if your not seeing the under voltage symbol when playing games I wouldn’t worry about it too much.

Cheers

Paul


#108

Hi Paul,

Thanks again for all the advice, I really appreciate it, you’ve been a great help! I agree with you, it doesn’t affect the games so I think just something to live with :)! I will try the final thing of connecting to ATX via molecular and will report back :)! It’s been a great learning project and I know all the tricks now for my second build!

I do have this cheaper crimping tool, can I use this for the molex (will solder too like you did)?

Many thanks!


#109

Lol not molecular (damn auto correct!)…molex :)


#110

Hi

No problem, happy to help.

I’m not sure that will work for crimping the molex crimps as they are quite small. A pair of pointed nose pliers should be fine so long as you solder the wire to the crimp afterwards. Don’t use too much solder though as you wont be able to get the crimp into the housing if its too bulky.

Cheers

Paul


#111

Cheers Paul,

Got it, thanks for the tip! Got a quick q for you whilst I wait for the molex bits and bobs to arrive.

Pi now seems to be stable and not undervolting. The only time I seem to get it is if I overdrive the audio to 100% and then turn the volume up high then I get the lightening strike and it slows the game down, so at high volume the speakers are drawing too much current from the pi. Could I add a second 12v 5v converter to the 12v DC in and use that to directly drive the Picade board? That way I’m not adding any total load to the 12v in, it should take the current draw away from the pi and may provide the speakers with the bit of extra juice they need? Also it won’t affect the ATxraspi interaction with the power button and pi.

What do you think?

Cheers!


#112

Sorry should have said although I don’t ever want the volume at 100% as it is too loud, it undervolts at around 65%

Cheers!


#113

Hi

You would need to modify the USB cable connected to the Picade PCB to remove the 5v and gnd connections otherwise you will be feeding the PCB with power from two separate locations. Other than that it should work however it maybe that the load on the power supply is close to the 5A it can supply as we don’t know how much current the display requires.

Have you set the volume in the RetroPie settings to 100%?

Cheers

Paul


#114

Hi Paul,

Ah yes didn’t think that through lol, forgot the Picade board still needed to be connected to the pi some way lol!

Been looking at this today and didn’t realise there were so many places to adjust volume!: Picade buttons, alsamixer, ES, & retroarch.

Initially the volume on the Picade was quite low even maxed out with the buttons, so I went into Retropie setup and increased the alsamixer value from 40 to 100. Then as I increased the volume using the buttons as it gets high it draws too much power and causes an under voltage. The limit seems to be around 67 on alsamixer at this value max volume on the buttons doesn’t trigger an under voltage. Might play with ES volume and retro arch volume tonight and not mess with alsamixer.

What settings do you have?

Cheers!


#115

Hi

Alsamixer at 100% and the Picade volume at around 15 if you lower the volume to zero then press the up volume button 15 times that will get you the same level. I set mine via a python program before the firmware was fixed.

Cheers

Paul


#116

Cheers Paul!

Been playing again and I definitely have a limit on my volume before it undervolts the pi, it’s probably around where your volume is set somewhere in the middle of the button volume settings (with alsamixer at 100). I think it may be something I have to live with which is fine as I don’t want the volume up too high anyway but will see if the molex connection on the ATXraspi gives it just that little bit extra juice :)!

Tried pretty much everything else, swapping out cables, unplugging additional peripherals, setting max amp USB out in config etc but no joy always at the same limit. Thought about a USB y cable to see if that helps but guessing it won’t as it is still drawing the same power from the pi?

May look at a build using a powered USB, still going through ATXraspi etc. Something like this

Would maybe allow for some more peripherals etc without voltage issues? Would prefer to use a panel connector and be able to disconnect the plug from the Picade (rather than route under the back door). Any idea if they do something for this type of connection for a panel similar to the DC in we used? Ideally it would have a panel connection for the usb hub power supply and then on the inside a short cable and plug that plugged into the USB hub.

What do you think?

Cheers!


#117

Hi

You can get these
http://cpc.farnell.com/tuk/kcuabbkpm/coupler-keystone-usb2-0-a-b-fem/dp/CS28096

This would mean you would then have two power supplies to switch on in order to use the Picade. One for the screen 12v and one for everything else 5v.

Cheers

Paul


#118

Hey Paul,

Ok so update on the undervolt issue. The molex connectors arrived so I connected them to a different ATXraspi and voltage converter, plugged that into the system taking out the installed converter and ATXraspi and I get exactly the same result, system stable no undervolt until I turn the volume up around 70% and then I get the same undervolt which slows the games down.

I decided to test some other power supplies, I plugged an official raspberry pi 3 power supply into the ATXraspi and I get exactly the same undercoat behaviour, if I take the ATXraspi out of the system and plug an the official power supply directly into the pi then I get no undervolt behaviour at all even with volume at max. So it seems perhaps I’m losing a bit of power with the ATX in the system, however I tried plugging the micro USB from the converter directly into the pi and I get the same undervolt issue so it seems that the converter itself isn’t providing the pi with quite enough power to drive the speakers. I did notice when I measured the voltage of the screen dc cable and the voltage converter that the screen cable is taking 12.1v rather than 12v and the atxraspi is getting 4.9v. I measured the voltage hitting the ATX whilst under load and as the volume is turned up it never drops below 4.9v at the ATX even when undervolting on high volume. Measured at the 5v and ground gpio pins the pi only gets 4.8v from the ATX, it never drops below this even when undercoating at high volume. When I measure the pi gpio pins when using the official pi power, it registers between 5.1/5v and never drops below this which indicates when using a converter and the ATX I get a loss of 0.2v when compared to using the official adapter at the pi gpio I can only assume it’s this loss which is undervolting the system at higher volumes. Do you see the same voltage numbers at ATX and the pi gpios on your system?

Based on the above can you think of a way to improve the power provided? Could it be the usb cable to the Picade board? I’m using the stock one but wondering if I need to use a higher rated cable to provide the power needed. Is there a way to measure voltage at the Picade board?

Any thoughts would be greatly appreciated. I know I could just avoid turning up the volume but I’d like to get it working properly and understand where the lack of power is coming from.

Cheers!


#119

What if I used something like this?

https://www.ebay.com/p/12v-to-6v-Dc-dc-Buck-Converter-Step-Down-Module-Power-Supply-Voltage-Regulator/1279123631?iid=182217356551

Would I do damage to the ATX board/raspberry pi providing it with 6v? Assuming that I will lose .1/.2 volts through conversion etc

Cheers!


#120

Hmmm looking online it seems 6v would cause damage.