Well, there are some complicated questions 
I suppose that the first thing I need to point out is that I’m working on this project in my spare time, as time permits, and I have 3 kids, the eldest of which will be 5 in a couple of weeks, so as you can imagine, there is very little sleep, and available time is quite unpredictable.
Which really means that I cannot make any kind of promises as far as time to completion goes.
I HOPE that I can get some kind of limited production for early testers by the end of the year or January.
The current hardware status is that I’ve just yesterday received another batch of unpopulated prototype boards, on which I believe that I’ve got everything actually working such that it won’t need any modifications for all board features to be functioning correctly. The previous batch was really good, except for a couple of very minor glitches.
Now everything working, of course, does not mean that I am completely satisfied with the board. I did cut a corner in this board that I have not entirely worked out yet. That corner I cut is that I used an aliexpress amfm radio module with an NXP TEF6686 tuner. While the module is “good and cheap”, there are a couple of serious drawbacks to it; its AM performance is barely above the level of “trash”, and there is an absolute lack of any kind of documentation available for programming the thing unless you feel like signing away your first born as collateral to their NDA.
So I’m implementing a 2-step way forward from that module;
- a “nearly” pin compatible custom module based on Si4743 (which has full public documentation), and
- integrating the Si4743 radio directly onto the mezzanine instead of appending it as a module.
When I say “nearly” pin compatible, I mean that the power supply is a bit different. The TEF6686 module requires a 5V supply and has an onboard 1117-3.3, but my mezzanine already has an L4931-3.3 onboard, with plenty of available capacity for the Si4743. So I’m powering it with 3.3v instead of 5, and delivering it through a pin which on the TEF module is NC, so despite the slight difference, it will ultimately be a drop-in replacement.
The second step is to eliminate the through-hole connector that is situated over the base board’s two USB ports, as well as reduce cost (not that this will make it cheap…). As I’m sure you are aware, there is not a ton of space above those USB ports, which means that the pins need to be clipped flush with the board before soldering in order to have enough clearance.
Now for the “current setup”… I’m sure you are referring to the sensors mezzanine + USB sound card + DMHD1000 configuration. I actually haven’t maintained that configuration into AOSP9, although some are reporting success with it still, after returning the audio HAL back to what it was when I was still working with that hardware. To be honest, I’d describe that design as a real pain in the ass, which is why I’ve moved onto the custom mezzanine – although I am still running that very setup in my car, and it does function extremely well. Before you ask if I have any real-world testing on the mezzaning, yes, I have that configuration installed in my wife’s car which she’s been using with very few complaints. Well 1 complaint, which directly tied to the TEF6686 radio.
As for the emulator, the value I’ve been able to get out of it is this; it gave me a real good picture of how they intend for it to look and operate. But when it comes down to it, I don’t think I had the AOSP-8 emulator running more than about 15 minutes, and the AOSP-9 for more than about 5 minutes. For me, it really all came down to taking in the visual intentions.
