On Fri, Feb 08, 2002 at 01:40:43PM -0000, Michael Rigby-Jones wrote:
> > -----Original Message-----
> > From: Bob Blick [SMTP:bblick@SONIC.NET]
> > Sent: Friday, February 08, 2002 3:16 AM
> > To:   PICLIST@MITVMA.MIT.EDU
> > Subject:      Re: [EE]: Car MP3 player. (oh no, again!!!)
> >
> > DOS? Yuck! Don't you have a hard drive size limit and 8.3 names? I
> > have full code(PC side and PIC side) if you want to use Linux and a
> > serial port.
> >
> Nice thing about DOS is that you can happily power up and down with vritualy
> no chance of causing any HD corruption.  Linux is a bit of a fscking
> nuisance in that respect :o)  Dos will also boot in a couple of seconds
> which is handy if you just want to turn on and get some music out of the
> thing.

This looks like a good opportunity to talk about my Linux based setup.

I use several tools to handle the power up/power down issue. First all the
HD partitions are mounted read only. All of the variable partitions (/tmp
and /var) are located on a ramdisk. So it can be powered down with
extreme prejudice and laugh at you.

My plan is to use a IDE Zip drive for transport. They're a steal at $29
a pop and can autoeject the disk without pushing out a tray. 100MB
will usually get you two CD's worth of music which is about the frequency
I transfer anyway.

I found the most annoying thing about booting in a car is the battery drop
during starting. So I have a micro UPS consisting of a 12V gel cell that
carries the system for the few seconds that the car is starting.

The last interesting item which I haven't implemented yet is LinuxBIOS.
Essentially you flash a modified Linux kernel onto the motherboard which
boots directly without all the pesky POST/memory sequences that standard
BIOSes have. Boots to a running state in less than 10 seconds and can be
powered down with impunity. Check it out at http://www.linuxbios.org.

By far the toughest part for everyone (except for Bob, Roman, and Russell ;-)
is the power supply. I've learned a bunch about both switching and linear
supplies in the last year. I'm in the final stages of my switching 5V
(based on Russell's design) LDO linear 12V (based on Roman's suggestions)
for powering the beast. I'm ripping a stack of CD's for it even as we
speak.

Edson, I haven't yet found a cost effective SBC for this project. My
small box is a Baby-AT Socket 7 MB with onboard sound, video, and
ethernet, using a 450 Mhz AMD K6. It's mounted in a 11x16x2 inch
organizing case with the removable buckets. This houses the MB,
13GB HD, and the zip. The power supply will be external to the case.

Of course it'll have a PIC based, serial interfaced, control panel.
Eventually it'll interface to a yet to be written program that will
interface with a set of scripts that I've written to control the play
mix on my home PC MP3 player. Commands such as skip, repeat, and find
are already in the arsenal. Normal mode is to play a continuous random
playlist.

The thought of having over 200 CDs worth of music at my fingertips in
the car is quite pleasing.

Good Luck on your project.

BAJ

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