My first version of the cyberdeck will probably be a chunky mess of different parts and boards inside. But I’d like to start making my own boards eventually to make things cleaner and take up less space inside the deck. From the looks of it, this would also allow me to trade my time for the cost of premade boards. But that’s going to be the complicated part.
I’ve been searching for the past few days for a chip that can run lcd or oled displays and the supporting components for powering them. But unsurprisingly not much info is out there for easy finding. I have managed to find a few lcd driver/controller chips on digikey, and they are pretty cheep too! But they don’t support the resolutions I’m looking for.
Then I realized, “the Raspberry Pi 4 can support 4k!” It’s also open source so I can look at the components used. I’m not even a novice at reading datasheets, but it looks to me like the controller for lcd displays is actually managed in the SOC (System On a Chip) where the cpu lives. Of course power to drive the display would come from elsewhere on the board, but the controlling the pixels looks like it’s done on the SOC.
So I started looking for SOCs on Digikey that I could get for cheep (I’m probably going to kill one or two on the way getting the cyberdeck v2 done) and could manage a display at the resolution I want. Turns out that Texas Instruments makes an Arm Cortex-A9. I did actually start by searching for the chip that the Raspberry Pi 4 uses, BCM2711, but all I got back were results for the Raspberry Pi 4. Not helpful. So after going through all the different chips that TI offers, I settled on the AM4379. These chips aren’t as cheep as I was hoping, seeing as a good number of ARM chips of lower speed can cost less than $10. Still, I can set aside about the cost of a grubhub order and get one of these a pay check.
But since this is a ball grid surface mount component, I had to learn how that is attached. Of course the first place I looked was youtube. I found this video, this video, and this video to give me ideas of what I’d be in for. It doesn’t seem too hard, but only by doing it will I know for sure.
Okay, so now I have an idea of the chip and an idea of how to solder it, I need to learn how to design for it. I opened KiCad and started looking for the chip in the list of components. It was not there, so I figured it may be too new for the KiCad library. I looked up on digikey how to get their library and downloaded the git repo (git comes installed on Macs, and I think most versions of Linux. Installing it on Windows isn’t difficult either) and imported the component library and footprints into my project. When I searched for the chip it still wasn’t there. What the hell?
I started looking around the digikey page to see if there was some kind of individual download for the library for just this one component and I did find a page that allowed me to download the compent for my library but before registering and downloading that I had already begun looking into the differences between KiCad and Eagle, which is another pcb design software that I’ve seen mentioned a lot while doing my research. I’d avoided it because it’s not completely free. While this is only one source, it does mention that KiCad does not support designing for BGA (ball grid array) chips, but Eagle does. I’ll have to look around a bit more; I don’t like going off the word of one source. I’m also certain that there is a plugin somewhere that adds BGA design to KiCad. But it’s worth taking a look at Eagle because of it’s integrated support for BGA design and routing.
When I searched for “Eagle pcb design” and found the link for Autodesk, I found that you can only get Eagle bundled with another tool called Fusion360. I then went to look at the pricing because I hate time limited, feature limited, or ad serving “free” trials. When I saw the price I almost Noped the hell out right there. Autodesk software has always been expensive. That’s why anyone I knew that learned 3DStudio Max in the 90s did it on a cracked version. But Adobe software used to be crazy expensive too, and they’ve dropped the sub for every one of their products to about $50 now, making it more accessable. Not Autodesk. A monthly sub for just Fusion360 and Eagle is $60! And that’s their cheepest bundle. If you get any of the more professional bundles, you’re looking at $500+ a month!
Still, I looked around a little bit, and by going to the Fusion360 page and instead of clicking subscribe, I clicked on the plans & pricing link I found out that the free download was not a trial (like it says everwhere else). It’s a full product, though nerfed in some ways that may not affect me. No collab in the software (that’s fine, I’ll use git), only 2 pcb layers (this may become a problem in the future, something I’ll keep an eye out for), 2 schematics (I’m not sure what this will end up doing), and only 80cm2 pcb size. That last one could also be a problem. 80cm2 is 8.94cm a side. I went back to the chip data sheet and after scrolling though the pdf for 260 pages, I found that the chip is 17.1mm on each side, or 1.71 cm. That’s small enough to fit on the board but takes up almost 1/4 of my space for other components. I don’t want to breaking things up into different boards. That’s the whole reason for making my own board.
So, I’m going to have to learn Eagle well enough to design my board in the free version, and then subscribe for a month, long enough to do the actual design, I hope. SO, after my current electronics course, I guess I’ll be hunting for a good Eagle course on Udemy.
So, after writing this, I was doing some more searching (I can’t remember what for) but found the Qualcomm Snapdragon 888. Right now I can’t find a way to get ahold of one of these other than to tear apart a $1300 phone, but I’m looking forward to using one in a future iteration of the cyberdeck.
I also started looking into the Arm Cortex A78 and how to get a soc chip running on this core. No luck yet, but it’s only been a few hours.
Why hunt down these flagship (and expensive) chips? Because who doesn’t want the best? New generations of technology usually bring better performance, lower power usage, or both.