Hi,
I'm need of some clarification before I can decide for a hardware platform for
my project. The TS-7xxx SBCs look very interesting but I'm unsure whether it's
the right choice. I'll with no doubt also be needing some help implementing
some of this =)
First let me describe my project and the scope I have in mind:
* It's basically a mp3 player for my car, but on a Linux platform which enables
me to do so much more. I'll use xmms which can easily be interfaced with from
my separate application which handles all I/O with the real world.
* I'm going to make an "old-fashioned" interface with push buttons and a few
dials. The platform will require DIO for the push buttons, and DACs for the
dials (old dial resistance for volume control). I've done a little testing
with a Phidget DIO/ADC board which works quite well, but if it not too
difficult, it would be preferably (cheaper) to use the SBC's own pins for this.
* I'll be needing a little display (e.g. 2x20) to show what song is playing
etc. I have model from Phidget in mind which should be relatively easy to work
with, nice API, possible to make custom fonts etc.
* I'll also need WLAN (for maintenance and mp3 sync), possibly GPS (for route
logging, maybe speed measurement, distance travelled), and maybe even GPRS/GMS
(for surveillance notifications over SMS). I imagine all these should be
connected via USB. That way I can easily do all development on a standard PC,
and move device and software to the SBC.
* I'd like the platform to able to run on the car's battery for a long time
(weeks) without draining it. I could be running in a low power state, but
still be able to run jobs that don't require much CPU. I'd also like the
platform to be able to wake up upon car ignition.
* I need enough RAM and enough flash ;) and 32MB/32MB seems more than enough.
(My apps will be written in C btw.; I don't think I'll be needing Java). MP3
files will be stored on external HDD though USB.
* Finally the SBC should have stereo audio out, and preferably also input for
voice memo recording and possibly for use with cabin ambience noise
compensation of the volume. The sound should be of an acceptable quality.
Now, I've been looking at some of the TS boards, but it's difficult to decide,
so I have a few question. It's mainly about whether the particular option is
important to me or not.
* Let me start by saying that I've looked out these two:
- TS-7400, mainly because of its ultra-fast bootup, 4 ADCs, and audio.
- TS-7260, mainly because of its low-power specs (car battery, remember).
But this only has 2 ADC =(
- TS-7200, mainly because of an option of 8 ADC.
* "Ultra-fast Linux Bootup". This sounds like a nice feature. But since I'd
really like for the device to be powered on always, and thereby really rarely
do a cold boot, I don't think I'll be needing it. Also, I'm unsure what this
bootup really includes. If it only counts for a specialized kernel, and not a
custom kernel with my own drivers and a minimum of real-world apps, then I
don't think it's of any interest.
* Audio. The TS-7400 has on-board audio. Does this include output as well as
input? And is it just a matter of soldering two mini jacks sockets on to the
proper pins, or do I need more hardware to make it work? And isn't a USB audio
stick just as good? And can anyone recommend any that play (and record) well
and most importantly: Are supported on ARM9 and? I've been looking at this:
http://www.terratec.net/en/products/Aureon_Dual_USB_9842.html
* More audio: My car is an old Mercedes-Benz 300GD. I could imagine it makes
some electrostatic noise. Will such a board be able to work under these
circumstances? Will I be able to get any decent audio out or will it drown in
noise?
* GPRS/GSM. I see TS sell this as an add-on. I'm not sure how important that
is, but it will definitely be new to me to develop for this. Therefore a USB
device would be preferable so I can develop and test on my PC without pulling
the SBC out of my car. Anyone who can recommend such a device? I've found
this, but it would be shaky =) http://www.dealextreme.com/details.dx/sku.12057
Also, how difficult is it to actually attach a "raw" GPRS/GSM modem? Is it
just a matter of using attaching a few pins from the computer's serial port to
something like this:
http://www.multitech.com/en_US/PRODUCTS/Categories/Embedded_Device_Networking/embedded_cellular_modems/
?
* Is it insane to let my car's battery power such an SBC 24/7? How long will
it run? I know I can insert some protection that guards my battery from being
drained, which under every circumstance will be a good idea.
That's all I can think of right now. Any other considerations I forgot to
make? I've never made something like this before, so I'm on quite new grounds.
I'm a electrical engineer but have mostly written software. I've worked with
embedded ARM9 and Linux, but not from scratch like this.
Allot of talk, I know! Any help is much appreciated =)
(Oh, and yes, I know I can buy a stock car mp3 player much cheaper and with a
whole less sweat, but that's not what I want. Also, I've been looking at the
Hawkboard and BeagleBoard which have on-board audio, but I don't think they are
as low-powered as these board, and I like the DIO/ADC of the TS boards.)
--
Stephan
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