Latching power switch to power board on and off via GPIO

[tonberryhunter]

I'm running Emuelec on my Odroid-C4 and am able to get the board to shutdown via the birdiging of gnd and whatever pin I set in the config.ini

Is there a way to reverse the logic so when a latching switch is released it initiates the same shutdown script?

I've done something similar before with the Raspberry Pi but that was using a shutdown script I made. Attached is an image of the circuit I made for the pi. Please forgive my non standard wiring scheme.

I wired everything up as I had on the Pi and when I press the latching switch it shuts down the system which is the opposite behaviour I want. I only want it to shutdown when the switch is pressed off.

[mctom]

Hi and welcome to the forum,

I think the shutdown pin expects momentary switch action, and not latching switch. More importantly, do you expect the SBC to turn on when you push the switch again? How did it work with RasPi?

Certainly it is possible to modify wiring, so the same switch action will result in reversed logic in electrical sense. I'll draw it for you once I fully understand the problem.
What kind of switch are you using? An exact part number would be helpful but if not, does it have two independent poles?

You may also find interesting two carputer designs from our forum members, @joerg and @zyssai, who both solved problems of reliably turning SBCs on and off.
viewtopic.php?f=206&t=39066&hilit=carputer
viewtopic.php?f=182&t=45350&hilit=gpio%274%27cars

[tonberryhunter]

DPDT 6 pin latching switch.

I wish these companies would include headers or something for powering things on and off. This is forever a problem when I make anything with SBCs. I understand this may be something handled by the power supply or power circuit in most other devices and SBCs are stripped off this stuff for the sake of versatility, space saving and cost.

[mctom]

SBCs are in vast majority of applications parts of bigger systems that has their own on/off switches.
I believe our hobby use is not even close to 50% of market share - hence no power switch.
However Odroid M1, for example, has dedicated power button and reset button pins.

The same can be done with C4 and N2, but you will need a different switch for this purpose, a momentary (unistable) switch, just like PCs had since around 1996.
https://wiki.odroid.com/odroid-c4/appli ... key_wakeup

I see you used the same switch to control a fan. Instead of that, I propose doing it right and controlling a fan according to a CPU temperature. You will need a transistor to make it work, but will only turn on when it's needed and as much as it's needed.
Here is a daemon I wrote for this purpose, I can help you make necessary changes to run it on your C4.
https://github.com/tomek-szczesny/gpio-fan-controller

[tonberryhunter]

I'm trying to make this thing as close to how a real Dreamcast functions but I guess some sacrifices will have to be made. I wonder if I could use a script to turn the fan and power LED off when that same momentary switch is pressed to shutdown the system? The idea is to at least give the illusion that the power has been cut to the system. I believe this is how most smaller embedded electronics work these days anyway. My Chromecast is never truly off it just gives the illusion that its off.

I like this fan control I usually just run my 5V fans at 3V but that's far from ideal really as the system does heat up especially during emulation.

Ive been designing this Dreamcast Mini in CAD on and off for several years. I'm far from an electrical engineer but have made some circuit boards in the past which I likely should do here as wiring inside this case is getting kinda crazy.



Here is a finished slightly smaller one I made in 2018.

[tobetter]

@tomberryhunter, I like your design and it's amazing...
Would you be able to share the OS image which you are going to run on ODROID-C4?

[tonberryhunter]

Its a modified Emuelec image ive been working on. https://github.com/EmuELEC/EmuELEC/releases

Video of the Dreamcast portion of the theme
https://www.instagram.com/reel/Cx7Q7sYu ... BiNWFlZA==

[L67GS]

Still a lot of 74XX logic circuits out there to make a one shot out of, or just program a microcontroller to be a one shot.

[tobetter]

Its a modified Emuelec image ive been working on. https://github.com/EmuELEC/EmuELEC/releases

Video of the Dreamcast portion of the theme
https://www.instagram.com/reel/Cx7Q7sYu ... BiNWFlZA==

If you use EmuELEC, there is one variable in boot.ini for GPIO power that you can connect to a momentary switch. Need a verification again for sure.
https://emuelec.discourse.group/t/gpio- ... eroff/1190
https://wiki.odroid.com/odroid-c4/appli ... key_wakeup

If you prefer to go for lock switch, you need to make another power input hole to your case and wire up to the pads on ODROID-C4 through the switch.
https://wiki.odroid.com/odroid-c4/appli ... ower_input

[mctom]

I'm trying to make this thing as close to how a real Dreamcast functions but I guess some sacrifices will have to be made. I wonder if I could use a script to turn the fan and power LED off when that same momentary switch is pressed to shutdown the system? The idea is to at least give the illusion that the power has been cut to the system. I believe this is how most smaller embedded electronics work these days anyway. My Chromecast is never truly off it just gives the illusion that its off.

I like this fan control I usually just run my 5V fans at 3V but that's far from ideal really as the system does heat up especially during emulation.

You are right, the majority of consumer goods have working microcontroller when they are off.

Unfortunately my youth has been incomplete as I never owned any gaming system in my life. So I don't know how Dreamcast behaved.
But @L67GS is right, in the worst case you could add a companion logic chips or microcontroller to do anything you want.
In case of LED that simply glows when C4 is on, you could use any GPIO and write a script that drives it however you like.

Using a simple fan control daemon guarantees your system will be only as loud as it needs to be under given load.

I encourage you to design your own PCB and have it manufactured in one of many companies that make them for a few bucks these days. OSHpark is one of them. Larger components can be selected so it's easier for you to assemble it.
You could implement all the extras you can possibly need, such as a fan control circuit, power button support and more, and make it fit to C4 header directly if you like. The community here will help you design it if you have little experience with electronics engineering. This is an easy project, perfect for a newbie in this field. @zyssai has made excellent designs using Easyeda, I prefer Kicad, it's up to you.

If you want the power button to be operated by bistable switch, this can also be arranged. You could, in fact, just cut the power supply of the whole C4, but only if all mounted filesystems are read only. So, no high scores in games, probably not what you're after.

The case design is mind blowing

[tonberryhunter]

Thanks for the info. Ive gone for the lazy solution for now til I have someone help me design a circuit and PCB. Ive made some PCBs in the past but Im just not liking the changes that they made to Fusion 360 in terms of PCB design. I used Eagle in the past but they no longer support it so its changed a bit since I last made a PCB.

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[mctom]

Eagle has always been terrible if you ask me. Last time I used it, that was still a product of a small company (German, I think?). And my workplace was so cheap we worked on the trial version
Then at some point all electronic component vendors wanted to have "their own" circuit design software, and Eagle was bought by Farnell. LCSC still has EasyEDA, and RS has DesignSpark, and so on.
After a while the short-lived fashion mostly died out, and now you're telling me Autodesk bought Eagle? Wow. I wouldn't

Now to comment on your diagram:
- Pin #1 and #17 are in fact 3V3, or 3.3V
- Surely you didn't mean 220k resistor in series with LED. Perhaps 2.2k, or 220R?
- How do you plan to undervolt a fan to 3V? Maybe you could connect it to pin #1 instead? This depends on the fan current rating though.

[tonberryhunter]

Yeah I meant 220R yeah sorry 3.3v Im not using them anyway. I made some progress in Fusion.

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Those JST PH 4 pin jacks will wire into a USB hub board I found on Aliexpress. It would prob be better to design a hub right into the board but thats a bit beyond my technical skills.

I opted for a simple momentary switch which makes sense. Ive tested everything already using wires and it all works as I want. Just would be more slick to make a pcb and simplify the wiring and soldering.

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[mctom]

Uh, it looks great and all, but USB data lines must be routed as differential pairs. On the other hand, on such a short distance, and essentially working as USB low speed device (a game pad), maybe that's alright.

Here's a quite good tutorial how to design a nice USB hub: https://circuitdigest.com/electronic-ci ... t-extender

I would love to design this PCB for you, but I don't have free time slots right now. If this could wait a few weeks I'd donate a weekend to this project.

[tonberryhunter]

Thanks for all the help I ordered a small batch of boards without the usb hub.

I also designed these USB edge connector boards to make connections between the daughter board and the Odroid easier.

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[tonberryhunter]

It's a truly fun project and I personally really like the Dreamcast design.

[tonberryhunter]

Thanks Odroid you make a great board and it emulates Dreamcast very well. <3 Check out my business page when you get a chance.

https://www.instagram.com/robertdunnart/

[rooted]

You are making these to sell? I thought this was a personal project.

[tonberryhunter]

You are making these to sell? I thought this was a personal project.

Do you get paid when you work? I've been designing and prototyping this mini system since 2018. This is my job. I actually go weeks at a time without making any money working on this stuff. I don't have a comfy $70,000 a year income and a indispensable amount of mental energy. Im fortunate enough to have a supportive family who gives me a place to live (single bedroom) and work (uninsulated basement). I'm actually on government assistance. Have the cheapest phone plan money can buy and drive an almost broken down 2008 mini van that hasn't passed inspection since 2014.

Get off my back and let me make money off of my skills and time.

[rooted]

You are making these to sell? I thought this was a personal project.

Do you get paid when you work? I've been designing and prototyping this mini system since 2018. This is my job. I actually go weeks at a time without making any money working on this stuff. I don't have a comfy $70,000 a year income and a indispensable amount of mental energy. Im fortunate enough to have a supportive family who gives me a place to live (single bedroom) and work (uninsulated basement). I'm actually on government assistance. Have the cheapest phone plan money can buy and drive an almost broken down 2008 mini van that hasn't passed inspection since 2014.

Get off my back and let me make money off of my skills and time.

I was asking because I was interested, I'm certainly not interested now.

[tonberryhunter]

Updates : boards arrived quickly and seem to be working as designed.
Also finished painting and detailing the 3D printed shells with custom made decals.

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[odroid]

I think you did a great job recreating the retro colors and feel of the original Dreamcast.
I hope you will upload the completed photos later. I'm curious what the four USB ports will look like with the case.

I wonder if the reason for using the USB device connectors rather than the USB host connectors was to create a natural appearance.

[tonberryhunter]

I think you did a great job recreating the retro colors and feel of the original Dreamcast.
I hope you will upload the completed photos later. I'm curious what the four USB ports will look like with the case.

I wonder if the reason for using the USB device connectors rather than the USB host connectors was to create a natural appearance.

Yes USB-B because it matched the original Dreamcast controller connectors more closely. I did design a variation with USB-C connectors but felt it didn't look as good.

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[mctom]

And this will require illegal USB cables according to the standard specification..

[tonberryhunter]

I fully agree that Type-B receptacle connector is looks much better.
But I have a concern as mctom does.

Since this great retro gaming console is not a generic consumer product, your decision is quite reasonable too.

[mctom]

I think this would be legal to release as a product, but the USB trademark cannot be even mentioned in any promotional materials.
Pretty much like Pine64 used a term "Digital video output" instead of HDMI.

And of course availability of such illegal cables will be limited to shady aliexpress sellers only.

[tonberryhunter]

I think this would be legal to release as a product, but the USB trademark cannot be even mentioned in any promotional materials.
Pretty much like Pine64 used a term "Digital video output" instead of HDMI.

And of course availability of such illegal cables will be limited to shady aliexpress sellers only.

It would be easy enough to switch it to USB-C input if I ever did sell it on the mass market. I've not had much luck mass producing in the past. You need friends with deep pockets and a good understanding of the Chinese language. I planned on including adapters with these limited units Im making.

[tonberryhunter]

Demo video

[tonberryhunter]

Also made a Dreamcast Controller to USB adapter.

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[tonberryhunter]

I think it's really cool.
Congratulations as the long development project appears to be almost complete.
I hope that the opening angle of the DVD lid can be made larger to make it easier to remove/install the SD card.

By the way, where did you buy the Dreamcast controller?
I am inquiring because I would like to have one for my collection.

[tonberryhunter]

Yes Im gonna try to increase the angle of the CD lid. The controller I found on eBay but this was before the pandemic so prices may have been cheaper then.

[tonberryhunter]

More pictures. Its tricky getting the hinged door aligned properly especially with the spring pulling on one side. I had to modify the spring assembly after the fact since the original spring was not strong enough.

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[tonberryhunter]

Im now working on a kit version for those interested in building and playing around with one of my Dreamcast Mini builds.

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