Why make it so hard?

Just connect all signals together to one input of a fast comparator by
equal resistor (a DIP resistor net come in handy) and the other input from
the wiper of a pot connected to Vdd and Vss.  Not only can it be much
faster, the program takes no time to compile ;) , and you can set the trig
level in real time with just a knob.

BTW, IMHO I think you better have the sampling running continuosly, writing
circularly in memory, and then stop, say, 80% of a "circle" after crack is
detected.  You will then also have 20% of the sampled data *before* crack
detect, so you can see how it started.

If you use a PIC it can control the memory adressing and circular counting.
 If you don«t need very fast trig detect, then use a many-pin PIC hadle
both menory and check the trig.

/Morgan
(analogoholic)

/  Morgan Olsson, MORGANS REGLERTEKNIK, SE-277 35 KIVIK, Sweden \
\  mrt@iname.com, ph: +46 (0)414 70741; fax +46 (0)414 70331    /