engine RPM via a hall sensor

Archiver

Hello,

For a school-project i'm building a test-system for a diesel engine
and i have to display the RPM via a LCD-display. I already bought 2
hall-sensors and a basic stamp 2SX. Can anyone tell me how to connect
and programm the stamp. As this is my first experience with a stamp,
i don't know where to start.

Gijs

Archiver

I have been using a BS2 and a hall effect sensor to collect RPM data
and have it displayed on a PocketPC. This is a great approach for
data acquisition as it allows the PPC to collect the RPM data over
time for a dynamometer program I'm writing.

If your hall effect sensor gives a 5v digital output you can couple
it directly to a input pin on the BS2 and use the BS2's count
function to count the pulses on the pin. You may need a pull down
resister to keep it from floating when the engine isn't running. If
your sensor has a analog output you will need to either read the
voltage and scale it to match the RPM or use a A/D converter w/serial
out. National Semiconductor has a chip they make just for collecting
Rpm's, LM2907. The LM2907 series of tachometer circuits is designed
for minimum external part count applications and maximum versatility.