Custom MP3/AAC/Ogg Vorbis player w/ color LCD design?
 

I've been beating the idea (and some basic plans) around my office for several years now, and I think it's time to get it out in the open.

For years there has been a movement towards open software based upon the GPL licensing scheme, and hardware designs aren't far behind. So, my proposal is simple. I wish to post up the design for a custom audio player (in particular, the hardware for one) in an attempt to get a dialogue going with the design community at large. As with open-source software, this will (hopefully) promote a better design by allowing people to add in new functionality and debug current functionality.

So that no one (including myself) has to go digging through old threads, I will reiterate my original plan. The board is to use a general purpose DSP (Digital Signal Processor) and NOT a chip specifically designed to decode any particular audio format (as is the case with the multitude of MP3 decoder chips). This has the benefit of not only being able to decode any current or future audio format (within the computational limits of the processor, of course) but also the added benefit of being expandable for other purposes (as I'll discuss later).

To be specific, I envision the board including the following components:
1) A Texas Instruments DSP, probably of the 'C6xxx family
2) A sizable hard drive, potentially expandable to four or more drives
3) A 7" color LCD, although size and color could be left as variables for the sake of expense
4) A USB port for downloading data, potentially Bluetooth or Ethernet
5) Flash memory to hold user settings as well as the program itself to allow reprogrammability
6) Standard SIMM/DIMM memory modules
7) An FPGA/PLD for easing the load on the processor, such as a DMA engine for hard drive connections (even though the TI chip has several DMA ports)
This list is by no means all-inclusive, and can/SHOULD be modified as we see fit.

So who wants to have another LCD screen in their car just for an audio player? Well, what if the screen/board also doubles as an OBD-II data logger, or even a logger for external sensors not controlled/seen by the stock ECU? Since the design is open to everyone, these sensors can be easily added on. With the availability of inexpensive GPS antennas and downconverters (not to mention differential GPS being well documented), how about a autocross track logger? The possibilities are endless! But I get ahead of myself...

So what am I looking for? I'm looking for the help and support of those fellow EEs and hobbyists out there who have half a clue about electronics. While a vote of confidence from anyone and everyone is nice, it will be infinitely more useful if those in the know are willing to step forward and help modify/debug the designs we come up with. You don't have to be a genius or an electronics whizkid, but if I can get a wide enough array of specializations I think we can pull it off more quickly (FPGA/VHDL programmers, high-speed/low-noise PCB designers, IDE hard drive/USB spec know-it-alls, etc.) People such as modifry, matrix, me, etc....

So, is this something you guys/gals are interested in, or am I forced to go this one alone? :)

MacGyver,

I am intrigued by your ideas. I'd be interested in lending a hand in this project. PM me so we can get in touch and see how to best push this idea forward.

A community of developers all contributing to the system would yield a powerful tool indeed....

-Jeff

Jeff,

Whenever possible, I would like to keep communications run through the board so that everyone can see what's happening (it avoids a lot of redundant emails). Should anyone wish to send info (datasheets, images, etc.) directly to me, you can use my standard address at MacGyverS2000@netscape.net . Other than that, I will try to keep images and such hosted here on s2ki.com.

I know there are at least a few others interested, so I'll post some stuff up. First off will be a schematic for the rough board. More than likely the alpha version will be hand drawn and scanned until I get a chance to enter it into Protel, but that will at least give everyone a chance to see what functonality exists, how to add more, and fix any buggies I introduce along the way.

Specifically, I will be looking for company name and part number suggestions. I work a lot with Digi-Key, but I would appreciate a few more large companies to help with on those hard-to-find part searches. Also, I will leave some of the part numbers open for now, such as the flash RAM, in the hopes that someone can make a suggestion based upon experience with a good brand or type.

My first request is...can someone find an inexpensive (<$50) BGA to through-hole socket manufacturer? I've found some test sockets, but they cost $800. The processor will be BGA and my soldering skills aren't THAT good, so for prototype purposes I will design the board as a through-hole design. The final product will be a surface-mount design where most everything could be soldered by hand if you have a steady hand (except the processor).

Let the games begin! :)

This may be jumping ahead, but so I can be thinking ahead, what did you have in mind as far as software for running this thing? Much of my background is in software development so I would probably be able to lend a hand later in the process than earlier. Some sort of thin install of an open source operating system? Linux perhaps? I've used extremely small footprint linux installs on firewalls and like appliances(the LEAF distro fits on a floppy so less than 1.4mb).

Would this work well as an embeded linux appliance do you think?

Ok now I'm getting excited about this idea :p Especially the prospect of cross car communication via bluetooth as well as possibilities in the areas of data loging, navigation, etc.....

Let me know what I can do to help, as I said the hardware may not be my forte but I'll do what I can.

-Jeff

why not just do the an interface device that connects the car's port, any sensor connections, and output - a/v. Plug it into a notebook computer and you'll have more flexiblity

Well I think the idea was to build a unit that could be seamlessly integrated into the car itself...... am I off base on that?

If you *were* to go with some sort of os embeded application, you'd have all the power that any laptop could give you and all of the expandability as well. Plus you'd have the benefits of having ready made USB/bluetooth/etc... already made and ready to go.

Just some thoughts.

Jeff: I would prefer to stay away from operating systems since the level of control is one more degree of separation from the hardware. I'm a firmware guy, so I spend most of my time writing and/or optimizing software for embedded systems...but I don't have infinite free time. Since the hardware is open source, if someone wanted to install an OS down the road, they're certainly free to do so. A possibility is using DSP/BIOS which is a license-free bare-bones OS written by TI specifically for use on their DSPs...the functionality is pretty impressive and the lost clock cycles/memory would be significantly smaller than a generic OS since it was designed and optimized for these particular chips from the ground up.

Oooh, never thought about cross-car communications. Shit, Jeff...you opened up a whole can of worms with that one. We could potentially have a radio system built into the board if we use Bluetooth. If multiple cars in a group had this setup, they could talk back and forth without Motorola WalkAbouts and such (if they were within a reasonable distance of each other, say a couple of car lengths or in adjacent lanes). We'll have to explore that one some more when the time comes.

At the moment I have a working MP3 software setup accurate to 24 bits, so I'm going to put a 24-bit codec on the board (no one bitch about not being able to hear the difference...the bits are available, so I'm using them, and that's that ;) ). Technically I can't sell the setup as an MP3 player without paying an unGodly license fee, so that software will have to be distributed as an 'upgrade', so to speak, and not as part of the board package itself. Truthfully, I'm not even supposed to provide the software, free of charge or paid, without licensing the technology, but since it's an open design who says I'm the one who has to provide a particular set of decoder software?

I started working on the audio section a bit, still running through the spec sheets to find a 24-bit codec that I like. Since the inclusion of jacks is all that's necessary, I will include both outputs AND inputs on the board. Now with your suggestion of car-to-car communications, it gives me a stronger reason to include the inputs. At the moment I'm including both RCA and mini-plug style, but that may chop down to just RCA for output and mini-plug for input in the final design.

There is also an opportunity to put an FM synthesizer chip on board, which means this has the potential to completely replace someone's stereo all together. I will most likely leave that to the next major revision of the board since we'll probably have our hands full cleaning up noise issues the first time around.

But I want everyone to be thinking not just in terms of an audio platform, but also a datalogging and control platform. The firmware and circuitry to datalog (engine temp, boost pressure, etc.) and control some basic items (like blow-off valves, lights/neon, etc.) is quite simplistic in nature. A reasonable question to ask the FI guys would be "Would you purchase a compact, yet expandable platform that allows realtime datalogging and control of your FI system, as well as play your favorite songs, if you could buy it for the same price as those 5 huge guages you just installed in your A-pillar and on your dash?" I would certainly be interested in hearing the answer to that question.





Lucid: For one, it requires a notebook computer...these are not only expensive, but bulky and unwieldy. Without major modification, you are stuck with the screen provided, as well. I'm looking to design something that will have the footprint of a 1 DIN head unit, but preferably smaller. By designing it this way, I can separate the control unit (buttons), the display unit (LCD), the processing unit (board itself), and the storage (hard drive, CD). It also means I have complete control over what is going on instead of an operating system (with the obvious downside of more difficult programming).

I suppose my overriding reason for doing this is because I enjoy the challenge of design and implementation. People may look at me funny, but I really have a lot of fun doing this type of work, even so much as to neglect warm-weather driving time in the S to play with an oscilloscope ;) On those days I save the drives for when my debugging sessions aren't going too well and I need a break :D




Keep the thoughts coming, guys. I'm all for hearing the pros and cons of what we're doing, especially the cons since they tell us if we're heading in the right direction.

Oh yeah...Jeff, since you are interested in helping on the software front, see what you can dig up on software (both embedded and desktop-based) for both Bluetooth and USB. I have never written applications using either of those, so i will be coming at it fresh and ignorant. We will obviously need some sort of desktop application/GUI for viewing datalog sessions (for times when the LCD just isn't big enough or you want to relax in the AC), downloading songs to the HD, etc.

Grrr, this is frustrating...I want to start working on it all as the ideas are just popping through my head, but this is why I've asked for help...too many ideas and not enough time/manpower.

well for the fun of the project and "climbing the mounting cause its there" Go for it!

Im not even thinking a NEW notebook even an old refurb closeout 1-2 years old can still power through you're looking to do. yeah bulky in SOME respects if you keep it in one piece and out in the open without hiding it in the trunk like an amp.

I dunno how youre getting an LCD in a 1 din size footprint unless you're going with those tiny ones.

Heh, no, I never would. I was designing this to be separate pieces from the get go. The control board (and HD, if the user chooses to keep them together) should easily fit into a 1 DIN unit. If I add in the FM receiver, there becomes fewer and fewer reasons to keep a standard stereo in the car, so this can take its space. The only reason I can think of off the top of my head (other than someone claiming a higher-quality output from an aftermarket head) would be XM/Sirius...no reason why we couldn't eventually add in the hardware/firmware for one of those.

The issues then become "How big of an LCD should I get?" and "Where do I place the LCD?". Mounting it in the dash is an option, as well as having it on a stand or an arm that sticks out...the available options will depend on what size, I suppose. As an option, I am also considering a new flexible LCD. It's actually an organic LED display, such as the one found at http://www.universaldisplay.com/ . they have a cool mpeg of it displaying moving images while being bent back and forth. The neat thing is it's very thin and can be stuck to the CURVED dash with something as simple as double-sided tape (although a clean install would be better). It's the ultimate in portability!

You never know what you're going to come across while surfing the net :)