T430 Ultrabay Companion Core

23/05/25

A little backstory:

I recently purchased a ThinkPad T430 for 60 dollars ($35 in freedom coins). It's pretty nice, though it's missing a battery and an optical drive. I ordered a new battery, but who even uses the optical drive nowadays? So, left with this empty space on the side of my laptop, I of course started thinking about what I could put there. Initially, I considered building a WiFi adapter module with an external antenna. Sure, it would look sick, but realistically, I can just plug one in via USB. That brought me down to two main ideas:

• An SDR module (Software Defined Radio)
• A Raspberry Pi co-processor module

I ended up going with the latter, mainly because SDRs are expensive :(

Research

Here are my core design goals: - Thin enough to fit inside the ~12mm tall Serial Ultrabay Enhanced. - Powered by the 5V SATA power line - Ideally boots without human input

My first thought was the Raspberry Pi Zero 2 W. It's very small, should be powerful enough, and can be powered by the 5V I get from the SATA port. Though I think it may be too small. Although its height is perfect for my usage, I feel like I could use something more powerful that doesn’t leave a lot of wasted space. That leads me to my next idea: the Raspberry Pi 3 A+. I couldn’t find an exact measurement of its height anywhere, but it seems to be around 12 mm. That would barely fit, and since I want a case, I need to factor that in as well. I could definitely make it much thinner by trimming down the headers—and maybe even the ports. Another option I found is the Raspberry Pi Compute Module 3+ with a custom carrier board. Perfect in theory, right? A custom carrier board would mean total control over the size, shape, IO, etc. The problem is, I have zero prior experience with PCB design. Before deciding on which board to use, I sketched out a rough template of the size and shape of the case that will go in the Ultrabay, based on the standard Serial Ultrabay Enhanced optical drive.

It looks a little funny, because I drew it out based on reference images, without getting the measurements first (and I didn't have a ruler, so I used a Steam gift card), but this should be good for making a 3d model for it. I'll probably hollow it out and get my friend to 3d print it, so I can get a feel for it.

A few hours later and I have made the 3d model for the container. I hollowed it out to save filament, and so I can see how much it can store in person. The main hole goes 11 mm deep, so I hope that will be enough to fit everything I need. As of writing this, I have just sent the email to my friend, and will probably go to sleep now, as it is past midnight. Or I might watch a few videos on PCB design. Still need to learn that.

23/05/25

PCB design time

I know next to nothing about PCB design, but for the Co-processor, I think I'm going to use the Raspberry Pi Compute Module 3+, meaning I have to design a carrier board for it. If that ends up being too hard, I'll probably use the Raspberry Pi 3 A+, and if that somehow fails, I'll use the Raspberry Pi Zero 2 W.

After some research, here are the main things I'll need:

• Compute Module 3+ socket (SODIMM-200)
• Power Input (from SATA power)
• USB OTG interface (Gadget mode)
• EEPROM
• 28x132 OLED I²C Display
• GPIO Breakout

I think I am going to do some PCB design practice by making the Hackpad starter project, before coming back to this.