Apple Lisa 3d Case Project

[wottle]

Made some more progress on the case. I think I'm going to try to make two case fronts, one for the iPad screen and one for the 11.6" screen. It should give flexibility.




I also posted about this on the main LisaFPGA thread, but I added the ability to control the output resolution at runtime by adding a special on screen menu accessible by long pressing the SEL button. it also gives the ability to adjust the picture location within the LCD, so hopefully it will help with getting it perfectly centered in the screen.



Still need to get the screen mounting figured out. The 11.6" screen may post some challenges due to size limits. But I think I can make it work hopefully by overlapping the LCD and the controller board by using longer standoffs for the controller so it can sit on a different plane than the LCD, easing getting things plugged in and avoiding interfering with each other.

For power, my goal is one USB-C input to power everything. I have found a nice nook for a USB-C trigger board that will serve as power for the thing. The 11.6 screen uses 5v to power it, as does the LisaFPGA, so I will have the trigger board get 5v, and then split that 5v to the screen and the computer. The iPad screen will require a buck converter because the iPad screen controller uses 12v, so I'll set the trigger board to 12v, run one line to the LCD, then another 12v line will go to a buck converter dropping that to 5v for the LisaFPGA (or Raspberry Pi). Hopefully this will allow everything to run off one USB-C power supply.

 

[wottle]

OK, I pretty much have the case design finished, with versions of the front piece for either an iPad 1024x768 LCD or the 11.6" widescreen 1080p LCD. And versions of the back case for either a LisaFPGA or a Raspberry Pi 4. I struggled a bit with my above mentioned LCD location adjustment functionality on the LisaFPGA, specifically getting it to save and persist the location between power cycles. But it is now working, and supports all three possible resolutions 1024x768@65Hz, 1080p30, and 1080p60.

I also had all my components set to install and power it all off of one USB-C input and ran into an issue. The USB-C male pigtail cables I was planning on using apparently are meant for pulling power from a USB-C device, not providing power to it. I should have realized this, since USB-C PD isn't a passive connection and simply providing 5v on the power line isn't all that's needed. I simply thought the 5V USB-C pigtails had the necessary resistors to negotiate that the cable would be supplying 5v. Apparently it is negotiating that it will pull 5v. And that causes my LCD controller board to do some weird things.

So, I'm looking into two options. One is to find the 5v line on the LCD and try to bypass the USB-C connection and supply the 5v line directly.
I'd prefer to avoid soldering if possible as it will make it easier for others to create their own if I can avoid it.

The other is to get a big USB-C male breakout board and add the resistor to make it act as a 5v supplier of power.

The third possibility is to have two USB-C ports on the back, one to power the LisaFPGA, and the other to power the LCD. The problem is I really don't have any room for a USB-C board in the port cutout area. the space is almost completely used up by the LisaFPGA board and ports, or the area with buttons. I could enlarge the back cutout, but it would mess up the symmetry with the feet. Not a big problem, but also not ideal.

Has anyone tried to power multiple USB-C devices with similar voltage like this on a project. Any good solutions? I suppose I could go with a 12v barrel jack and try to use a buck converter, but it really feels like maybe there's just a problem with powering both the LisaFPGA and the LCD off the same power supply...

Here's a video of it in action: