Embedding into RasPad 3 case

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Sorgelig
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Embedding into RasPad 3 case

Unread post by Sorgelig »

I've received several days ago interesting case RasPad 3 from Kickstarter: https://www.kickstarter.com/projects/ra ... rogramming
When i've saw it first time i've immediately thought it's possible to integrate MiSTer inside.
Thanks to developers who don't assign very specific place for Raspberry Pi and give a lot of freedom to integrate something else.

So it turned out embedding of MiSTer wasn't easy, it was super easy! Space inside is deep enough to accommodate even standard SDRAM vertical module. Originally i was thinking to add some retention using RPi holes, but SDRAM module has height just exact to case height inside, so it keeps MiSTer perfectly. Additionally cables keep the board in place.

The only challenging thing was to find a short thin and slim MicroHDMI - HDMI cable. I've found 50mm cable. 20mm or 30mm should be even better.
I've soldered MicroUSB -> USB-A cable to get RasPad 3 USB hub working.
Also soldered Type-C -> barrel cable to power the MiSTer.
MicroSD card breakout cable is unfortunately too short for MiSTer. You can try to find a longer ribbon cable. I've decided to go a simpler for me method - i've soldered the cable :) But even without extension cable you can use SD card directly in MiSTer. It's seldom need to be extracted.
The only breakout cable was used without any change is Ethernet :)

That's all.
Here is the result:
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1) USB hub in RasPad 3 is USB 3.0 and it works fine in USB 2.0 mode (de10-nano has USB 2.0 only).
2) Battery works fine, but i can't tell how long it lasts yet. Charging circuit is classic slow charger, so it needs quite some time to charge.
3) RPi4 has two HDMI outputs, and RasPad3 uses this feature to use LCD panel and external HDMI at the same time. MiSTer has only single HDMI, so external HDMI is not working. With some additional work it's possible to integrate some small HDMI splitter and get external HDMI working too. But i suggest to have just additional MiSTer for RasPad3 for mobile-only use.
4) Internal speakers work fine from HDMI source. Audio is muffled though. You need to lift the RasPad 3 a little to get a better audio.
5) RasPad 3 board works quite independently, so you get icons for charging and discharging as overlay on top of MiSTer video. There are 3 LEDs on the side to show the current charge level.
6) Original fan is quite noisy even in slow mode. I've used my favourite quiet ADDA fan without heatsink. That should be enough as originally FPGA is supposed to work in up to 100 degree. Effect of this cooling isn't so good, but enough i think.

The only thing i couldn't make work is touchscreen. It's not that touchscreen is really useful for MiSTer, but would be good to make it working. I had plan to simulate a light gun for supported cores. That would be fun and a whole new experience.
Unfortunately de10-nano simply doesn't see touchscreen at all. Even lsusb doesn't show any unknown USB device. Probably it's a classic de10-nano USB host issue when some devices simply don't work.
There is also a chance that touchscreen somehow depends on HDMI and may be needs some additional initialization. Actually i've tried to connect USB hub to my Windows PC and it also doesn't see the touchscreen. I've tried RPi4 - it sees the touchscreen, so i've confirmed it works in original RPi4 config.
So probably i'm missing something here.

But anyway RasPad3 adoption already works fine. You get a portable MiSTer without any difficulties in embedding process.
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limi
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Re: Embedding into RasPad 3 case

Unread post by limi »

This is great! I’ve previously wished I could build a version of this form factor with the low-latency, 4:3 aspect ratio iPad screen — it’s fantastic that there’s a simpler option available now.

By the way, is it capable of standing upright (“TATE”) on the side that does not have the USB ports, for games that run in vertical mode? (Mostly arcades)
warham
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Re: Embedding into RasPad 3 case

Unread post by warham »

ive bought small flexible cables from this place in the past

https://www.aliexpress.com/item/4000300793063.html
Duffygag
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Re: Embedding into RasPad 3 case

Unread post by Duffygag »

Not bad at all!! I still have to finish my ipad screen build :)
Ashenshards
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Re: Embedding into RasPad 3 case

Unread post by Ashenshards »

Finally a use for the gyro ? I think the de 10 has some kind of built motion / movement detection doesn't it?

Thanks for sharing this project. I might have to consider making one of these.
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Re: Embedding into RasPad 3 case

Unread post by Rikko »

Pardon my ignorance, but what do you actually gain other than having a MiSTer in a box with a screen?
128Mb v2.5 @150MHz
USB Hub v2.1
IO Board v6.1
built, not bought
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Re: Embedding into RasPad 3 case

Unread post by ToothbrushThreepwood »

A portable, self-contained unit with audio, video, controller input and battery power, as I understand it.
My question is if the battery time with a DE-10 Nano is similar to the 5 hours they advertise with a Pi?
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Sorgelig
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Re: Embedding into RasPad 3 case

Unread post by Sorgelig »

Update:
got touchscreen working. It's forcibly disabled if secondary HDMI is not connected (RPi4 has two HDMI outputs). To workaround it I've soldered a jump wire to always enable 5V supply for touchscreen board. Purple wire is what i've soldered:
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MiSTer recognizes it but for correct use i think it will need special support in Main.
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Re: Embedding into RasPad 3 case

Unread post by belgarcat »

This is great! I'm really tempted to get one of these, and being able to play lightgun games with touchscreen would be really interesting!
Rikko wrote: Tue Jan 05, 2021 4:57 pm Pardon my ignorance, but what do you actually gain other than having a MiSTer in a box with a screen?
Portability
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Sorgelig
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Re: Embedding into RasPad 3 case

Unread post by Sorgelig »

another option to enable touchscreen is to solder 0402 resistor with 100k on outlined place:
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Re: Embedding into RasPad 3 case

Unread post by Sorgelig »

RasPad3 includes Type-C to Barrel cable supposedly to use generic Type-C charger instead of included bulky AC adapter. Unfortunately they missed the point. This cable requests only 12V from charger while fully charged battery gives 12.6V. So you won't be able to charge RasPad3 fully by this cable. I've no idea what they were thinking to design this cable..
To use generic Type-C PD charger you will need to use this connector with small PCB configured for 15V: https://www.amazon.com/gp/product/B08P4PQ6D4
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Re: Embedding into RasPad 3 case

Unread post by Sorgelig »

After experimenting with HDMI to get it on internal screen and external one, i found to conclusion that simple wires splitter to both HDMI connectors doesn't work. Secondary port acts as an antenna receiving the noise. It doesn't work if external monitor isn't connected. When external monitor is connected then both internal display and external are working.
So, there are only 2 options:
1) connect HDMI only to internal display and leave external HDMI unused.
2) use some miniature HDMI splitter inside the case.

And since i want to explore the edge cases, i've decided to try to integrate the splitter to see if it fits.
Here it is:
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It looks messy, but fits :) Now i can use external display.
Also i've added small USB hub to USB Blaster and USB console connections. Normal user won't need it.
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Basically everything of RasPad3 is supported now. Only minor thing is missing: 3 I/O buttons and 3 LEDs. They are not very important but i will think how to add them. Probably a small breakout board on the back near GPIO hole can be attached.
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Re: Embedding into RasPad 3 case

Unread post by belgarcat »

Wow, you actually supported the touchscreen in lightgun games, I can't wait to test it once I receive my raspad. Thank you!
I've also ordered the touchscreen for the ipad3/4 screen, I wonder if it will work. https://aliexpress.com/item/32979840359.html
Also, I like the HDMI splitter to allow a tvout connection. Does it work directly or do you have to press a button to switch between screens? Which model is it, can you post the link or the model name? Thanks!
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