This one is a quick update, to let you know I am still alive and making progress!
Aside from the mechanical aspects, I have continued to make progress with the software, making things faster and testing more systems (with outside help). I encountered some issues on older systems that I eventually confirmed were due to voltage levels. An early choice I made was to use bus switches, as I wanted to maintain individual control of direction on pins to keep some options open for playing with a few things like ZoomVideo or other possible functions I was not aware of but may encounter. I now know ZV is outside the scope of what this card can do, so that requirement is no longer needed.
I noticed the issue on the HP 200LX. As I started to get the code faster and optimized, I started to see bit errors periodically. I eventually confirmed that the RP2350 driving the GPIO at 3.3V through the bus switch was not enough for some of these older systems, in particular those with unbuffered sockets.
So I have now made the move to the more standard approach of using LVC16T bus transceivers. As I had already purchased the full qty needed of the other part, I will need to think of a future project to use those if I am unable to return them.
I have completed a lot of exciting work with the firmware and drivers and will share some demonstrations in the coming days as I wait for the hopefully final hardware with the updated bus interface.
The bad news here is that this is for sure going to add several weeks. I am very happy with all other functions of the card, so once I receive the new test boards, likely next week, I am confident I can test very quickly to confirm the bus interface is acting as expected, and I will move on to production quickly.
I am also confirmed for VCF Midwest in Chicago (September 12-13), and unlike all previous years I should have a finished product this time! For taxes and other reasons I will not be selling them in person but I will certainly have some cool stuff on display.
Awesome work. Glad to see you’re still doing well and your work is still progressing along. I’m simply amazed that you’re able to pull this off. I was looking for a sound card for an old Zenith Z Note and stumbled across your project, since the Z Star lacks internal sound this is perfect for that and so much more. Looking forward to putting this to work.