Report
Changing the WiFi on a Raspberry Pi without entirely rewriting the OS (using the imager) turns out to be a relatively straightforward task, assuming you have current access to the OS. Changing the WiFi on a Raspberry Pi without entirely rewriting the OS while you don’t, i.e., when you’re on the opposite side of the state to the network it’s set up for, is virtually impossible. It didn’t used to be, though- on previous versions of Raspberry Pi OS, pre-Bookworm, it was just a matter of creating a specific file in the boot directory of the SD card and putting the network information there in a specific format. And since so many people in the Rasppi community simply do not like to call out by name the version of the OS they’re working with, it took a frankly unreasonable amount of time to figure out that that method had been deprecated on the version I’m using, and that’s why it wasn’t working. (In fairness, I suppose, the new version of the OS is very new, only a few months at time of writing, so the vast majority of the discussion out there predates it. Unfortunately, the new version of the OS is very new, so the vast majority of the discussion out there predates it!)
CMU-DEVICE requires registry using the device’s hardware address, which is easily identifiable with arp -a on my laptop’s terminal given that it and the Rasppi are on the same network, I know the Rasppi’s IP address, that the two had been recently in contact. What I ended up doing was flashing my second SD card with the WiFi information for my cellphone’s hotspot, connecting both it and my laptop to that hotspot, using an IP scanner to identify the Rasppi’s IP address, pinging it, and then calling arp to get the MAC address. Success. My device is registered with the WiFi! Now how do I get to the WiFi? It’s no longer something stored on the hardware- I need to modify the SD card with all of my work on it from last week without destroying it.
There’s no good way, turns out. I ended up changing the login information of my phone’s hotspot to spoof my home network so the Rasppi would connect to it, then sshing in on that network to use rasppi-config to update the information. It felt very silly, but it worked, so sure! Alright! In retrospect, if I had started by spoofing the old network I could have skipped using the other SD card entirely, so if I have to change the information again going forward that’s the way I’ll do it.
My week has been… nothing short of insane, on account of one specific project I have in another class that ate me alive, so I haven’t gotten a chance to sit down in front of a monitor that takes HDMI or wire up the Rasppis to be able to talk to each other. I’ve done a good bit of research and am pretty sure I know how to make the I2C, HDMI, and AV out work, so RF project willing I’ll be sitting down early this upcoming week to get at least temporary wires running between the Rasppis. I’ll probably have to solder them in, since the boards don’t have pins, but I’m going to try to do the lightest-weight job I can since I’ll have to take it out and redo it eventually. I also realized that I need to get my hands on another USB Micro cable, since I only have the one but will have to test-power both of them at once pretty soon. Gonna ask around to see if anyone I know has one that I can borrow lying around this weekend, then just order one on Amazon early next week if not.
Progress Schedule
Unfortunately the radiofrequency project that came out of left field (I knew it was coming, didn’t expect it to be nearly so insanely difficult as it was) has put me on the back foot with regard to literally everything else. I might have to abbreviate some of the HDMI work I was planning on doing since we are approaching pretty quickly when the displays are going to be delivered. Gonna be playing catch-up this week.
Next Week’s Deliverables
I need to get the boards talking to each other, which may be early this week or may be late depending on whether or not I can get my hands on another USB micro cable quickly or not. Also want to get HDMI out working, since that was supposed to be this week and ended up falling to the wayside.