I’m building an audio device. It runs Linux for the control plane (it’s just a CM4 running Yocto, maybe I’ll leave SSH running on production units, maybe not, haven’t decided yet). No audio passes through the CM4, there’s a dedicated FPGA and MCU for that. It’s been a fun project, first time hardware for me, feel free to ask my anything!
Nice!
This particular box also has RS-232, ssh (with almost zero auth), and telnet as a control plane, by default. Any of that only gets used to tweak/report various things with a rather basic human-readiable protocol. (It has built-in functions to make it more secure; I just don't care on my home LAN, or on my pop-up LANs in the field. A sane person with a professional role would have it locked down and on its own VLAN/VPN, but for me and prototyping: Telnet is actually pretty good.)
I designed none of it. I just bought it, and make good use of it. New, it was a mid-4-digit box; used, they're not so bad. (And I use it every day and like it quite a lot, hence the reluctance to go harder on the potential root shell hack.)
My box, as it sits, just does general-purpose GUI-connected DSP stuff with near-realtime tweaking. I'm in the process of getting it to grok OSC, and thus Reaper or whatever, so it has a better control surface for live work.
It has a USB interface that my Linux box treats as a sound card, which works well. My main reason for wanting to get root is to examine (solve?) its ~5-minute boot times.
5 minutes in a live sound environment is the difference between having a large, active, and involved crowd, and having everyone get bored and find something else to do.
Anyway, the FPGAs here just exist to behave as DSPs and...well, digitally process [audio] signals. It works well; I really just wish it booted faster.
And that may be its downfall. :P
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But enough about that.
What's your device do? What are your plans and dreams with it? (Do I want one?)
I've built a very small amount of hardware. At least at the level of custom PCBs and some code, it's been richly rewarding even when I screw it up, and it makes me feel like I'm on top of the world when I get it right.
Can you tell me about your widget?
Re: yours, that is a _long_ boot time. Boot time on mine isn't great, but I think I'm just going to have to accept that as an artefact of U-Boot, Linux, and an Ethernet switch chip that takes some time to initialise.
Anyway, re: my widget: it's a personal monitor mixer [1], something one might use in the studio or live, not dissimilar to existing products in the market, except: it supports up to 64 channels of Dante or AVB natively, it has a super nice (HiDPI) UI, and absolutely everything is remote controllable using OCA (AES70) or OSC. I even have a MCP bridge so you can let Claude manage it ;) [2]
The hardware is a custom board that hosts a CM4 SOM (for the control plane and UI), a Brooklyn 3 SOM (Dante), and an XMOS which runs the mixer firmware and AVB stack. There are also some nice AKM DACs, and a Marvell Ethernet switch chip that connects the SOMs and XMOS to two external Ethernet ports.
The CM4 runs Yocto which manages the switch in DSA mode (i.e. hardware offloaded bridge), runs the gPTP and SRP stacks for AVB, the OCA daemon, and the UI (which is just a regular OCA client). SSH is presently enabled but there's not a lot to do once you're in there. Working on secure boot at the moment with U-Boot and dm-verity.
[1] https://forums.swift.org/t/an-embedded-audio-product-built-w... (note, older prototype)
[2] https://www.linkedin.com/posts/lukehowardmusic_heres-a-long-...