It’s great that you are open to folks contributing, however it’s not safe to assume that everyone who uses ASL is fluent in Linux & c development, and thus should go make their own features. Open source projects need community support, and taking this attitude towards feedback shuts that down. I’d happily take a crack at it, but the development documentation is very sparse, and seems to assume a very high degree of preexisting knowledge. I cannot even find the code that deals with PTT & COS looking through the repo, nor am I confident that I could successfully build this on the only linux machines I have - 2 Pis.
And yes, I realize that I could buy the chip, but it really isn’t as simple as “buy chip, make board” that requires an even deeper level of knowledge, such as how to design the surrounding circuitry, design a PCB, making a PCB, solder a surface mount package (which requires equipment your average ham doesn’t have) etc…
The link you posted to Amazon is out of stock, and if you keep watching that link, you might notice that the in stock date keeps changing. I did find one that is ostensibly in stock, and will try to get it, but I’m also a bit hamfisted, and have had bad luck soldering to this very same chip in the past (I’ve destroyed 2 of these adapters trying to solder on them in the past). Yes, even using a pre-made USB adapter assumes that someone has a high degree of soldering skill.
Meanwhile, I have been able to build 2 dedicated PC interfaces for my radios using simply the audio portions of USB audio adapters, transformer isolation for the audio, USB serial with opto isolation for PTT, cat control (I couldn’t get the opto circuits to work there), one where I had to build a circuit to invert the logic signals, and a hub to tie it all together with 2 of the ports removed and the adapters soldered directly to them to save space. So I’m not unskilled at building stuff for radios, soldering, rework, etc yet I still can’t manage to reliably pick up a single pin on a small package like that.
So my point is, there are much more user friendly solutions out there. There are even pre-made boards for the audio and PTT isolation (2 of these would give you isolation of audio, PTT and COS for 2 radios for a duplex node) that cost something like $8 apiece.
But moreover, I just think it’s a bad idea to put all of your eggs in one basket. Even if ASL decided to support USB serial and NOT GPIO, I would support that move. Yes I would have to buy another adapter for about $5, and even sacrifice another USB port, but at least it would make the modification easy, and would work on both PC and Pi, and give me the option of picking my chipset (CH340, FTDI, Silabs, etc) or not even caring what chip was on the board. This makes the hardware solution trivial - Buy any USB audio adapter, any USB serial adapter, connect 2 wires from each radio to the audio adapter, and 2 from each radio to the serial adapter (GND/DTR or RTS and GND/CTS).
73 af7ux