Thor data logging

[Ludis Langens]

Thor Johnson <thormj at ibm.net> wrote:
> How much data is necessary?  If I log every point at every rev, I get ~5K/sec,
> (@13K RPM) which after 20 minutes is about 5M.  I know I won't be running full
> RPM throughout the course (which will make timestamping this difficult), but
> keeping that qty of data in the ECM seems a little much....but I don't know what
> I could throw out.

If you want to capture data with each revolution, don't store the RPM,
just timestamp each entry.  Later, you can compute the RPM from the
difference between two timestamps.

Five megabytes is a lot, but not much of that data is changing quickly. 
You could compress the data to much less than 5M, or store more than 20
minutes.

In the world of laptops, 5M is not a lot of memory anymore.  You should
be able to cheaply pick up a several megabyte low power laptop memory
module.  If you don't want to bother designing an interface to this
memory, then draft an old obsolete laptop for data logging.  Stuff it to
the gills with RAM, strap it to the dash, and interface it to your ECM.

I have an old Mac laptop with 8M of RAM.  About 7.5M of that could be
used for data logging.  In sleep mode, it can retain all this data for
days without being plugged in.  I also have a solar panel for this
system.  This panel puts out enough to run the laptop and at the same
time charge it's battery.  The panel can be taped to the inside of the
windshield or sunroof.

               unsigned long BinToBCD(unsigned long i) {unsigned long t;
Ludis Langens     return i ? (t = BinToBCD(i >> 1), (t << 1) + (i & 1) + 
ludis at cruzers.com            (t + 858993459 >> 2 & 572662306) * 3) : 0;}