Also, perhaps a 5" - 5.8" LCD mounted in the drivers sun visor. I am investigating this route to mount a screen for a navigation/dvd player right now. A couple have done it and I think it would be fairly easy to produce even preassmbled units. May even be possible without re-covering the visors....

-Jeff

Posting to register for my own thread ;) Forgot to do it originally...

Hmmm...I expected a bit more discussion and a lot more people being interested in helping. :(

OK, I finished a rough draft of the audio schematic. I'll post it as soon as I can find a decent scanner. I didn't do an exhaustive search, but I ended up working with the Cirrus CS4272. I believe Cirrus purchased Crystal Semiconductor a while back, and since CS's chips were always easy to interface to, this seemed like a good path to take. The specs are reasonable:

* Up to 24-bit data length
* -100 dB THD+N
* Volume control (1 dB steps)
* External oscillator use is optional
* Up to 192 kHz sampling rate for oversampling

I added in a few more details on the audio input/output side of things...connectors (RCA, mini-plugs) and such. Finished with the reset circuit (using a chip from Maxim), and threw down a rough draft of one of the power supplies (using a chip from Linear).

I plan to support (at least for the prototype) both 40- and 44-/50-pin IDE connectors. The 40-pin is for the standard desktop HD with a separate +5V/+12V power connector. The 44-/50-pin connector is for SFF (Small Form Factor) HDs, like those used in laptops, which runs power to the drive through the IDE cable. I want to separate the potentially large and noisy power needs of the HD from the rest of the board, so I may put in a separate power supply circuit specifically for that connector style.

The larger connector is more simplistic in terms of wire bundles to the drive, but it also means placing more power components on the main board. I haven't yet decided which is the lesser of two evils, but I suppose that's why it's called a prototype.

I made a command decision and decided against putting any sort of power amplifier on the main board. The goal will be a clean audio signal (preferably a differential signal to get a full 5V peak-to-peak swing) up to the edge of the board...anything beyond that is up to the user. This has the nice advantage that brain power can be focused on very clean pre-amp signals, and anything dirtying that signal with a bad amp will be the user's choice, not mine (I love it when people can't blame me ;) ).

I suppose the next item I attack will be the JTAG connector for the DSP and the IDE connectors themselves. I have assumed all along that I will place some sort of FPGA/PLD between the HD and the DSP to take care of the housekeeping tasks of reading/writing the HD, but for the prototype I will start with the housekeeping tasks remaining as software running on the DSP. I obviously won't get everything on the software side running at once, so once I feel comfortable most of the I/O functionality is there, THEN I'll move bits and pieces back out to the hardware side. I knew several board revisions was going to happen, so I might as well simplify my life at each step.

I need to start thinking about USB at some point. I figure if an 8051 at 25 MHz can handle a low-speed port, a 200 MHz DSP should be able to handle at least as much, if not full-speed (maybe high-speed?). It's a new area, so I'll have to take that one slow, but it's probably wise to install the minimal hardware on the board from the get go.

I also need to think about how I'm going to interface the real world (name your sensor) with the system as a whole. I may start out with something as simple as a handful of analog and digital I/O lines. I'm thinking something along the lines of 8 A/D input lines for those standard sensors we all want to look at...temp, pressure, etc. Say another 8 digital inputs (for simple switches) and 8 digital outputs (for controlling bottle openers, etc.). Maybe throw in a few PWM inputs for speed detection, etc.

Not much contribution from the community at large (which is QUITE surprising, if you ask me) , so I guess this is becoming more of a public journal of my design as opposed to a team effort. <shrug> So be it...the community will be forced to wait that much longer to see the fruits of my labor :)

Found it...Interesting project but to be honest I am with Lucid on this one. Just get a cheap laptop, use the external monitor output and a touch sensitive film to the com port and be done with it.

I can understand you may want more out of this, there is always an element of personal pride on anything you build yourself and that is great :).

To be honest I just finished my audio upgrade and am scratching my head as to why I even bothered doing it in this car. I hardly listen to the stereo and with my new exhaust, it makes listening to music even more of a challenge.

I appreciate being mentioned as a possible contributor to your project :), but with the little free time I have I would rather be enjoying the car than working on a project which I would get little out of (this does NOT mean that the project is not worthwhile).

Que sera... :)

I'm neck deep in the hardware design now, so unless someone offers me a job anytime soon, I'll continue working on it. There's SO much information that I need to bone up on...IDE, USB, LCD, and quite a few other acronyms. The majority of my time is spent sifting through the masses of spec sheets out there to determine which chip is best for the job (not to mention which ones are available). I eventually decide on chip 'A' knowing it might change to chip 'B' sometime in the future, which will also necessitate a circuit change. I can live with that, I suppose.

Damn, but that IDE spec is huge...188 pages :eek: I spent today doing some preliminary work on the interface, but I'll probably put off finishing it later. I think it's time to choose a Flash ROM and some SBSRAM so I can put together some sort of coherent interface between the major chips and the DSP itself.

If things continue the way they have (and the phone only rings for job interviews :D ), I hope to have a hand-drawn schematic of the entire system finished by the first week in May. I'll keep posting my progress, as usual, if for nothing else but to keep it near the top in the hopes someone decides to jump in and help.

Mac,

I'd love to help out... unfortunately, my electronics skills are quite amateurish. I've done the 'build a pc for the car' thing in the past and always anticipated doing it for the S, but just haven't had the time yet. One thing that's very helpful on a car-pc IMO is a network port (either ethernet or wireless). I know you're trying to stay away from an OS dependency, but a device that shows up as a windows share on a home network is way cool.

There's no need to use an OS on the board merely to have a network port. The same is true for USB. The only thing necessary is a stack, and that's OS-independant. I figure more people have a USB port than a network port nowadays (especially on the front of the computer, easily accessable), although that may change. If I can get the USB running at full-speed, that's 12 Mbit/s, better than the old 10-Mbit/s network cards. Enough to download your typical song in 2-3 seconds. I will certainly look into the requirements for running it at high-speed, but unless the DMA controller sprouts wings, I think it's going to have trouble keeping up with over 400 Mbits/s.

Mac -

admirable pursuit here... and while i do enjoy and am reasonably proficient in both audio and PC pursuits... you're operating way above my electronics skills... sorry i can't really help here...

i would like to point out however - that while USB is more commonly offered now, Ethernet also has a much larger functional and affordable cabling distance (i believe USB is limited to something on the order of 5m, and i seem to recall that Ethernet is 100m). so an Ethernet port would allow for a hard wire connection to a desktop PC vs having to use a laptop or something to upload music.
plus, for those who don't have Ethernet, USB style NIC's run in the $30-$50 range now...