hall sensor?not what is it

[xxalexx at ix.netcom.com]

> From:          "Duane Reed" <duanered at pacbell.net>
> To:            <diy_efi at efi332.eng.ohio-state.edu>, <diy_efi at coulomb.eng.ohio-state.edu>
> Subject:       hall sensor?not what is it
> Date:          Mon, 23 Feb 1998 17:24:54 -0800
> Reply-to:      diy_efi at efi332.eng.ohio-state.edu

> in my quest to retro fit a GM ecu (1227148) on a Toyota I pose a question may be one of the group members could answer
> 1    the hall effect sensor on the crank  for the GM calls for the sensor to be mounted at the falling edge at 70 deg btcd OK now the question how do I determine or check this falling edge for placem> 2     the cam sensor I do not have the cam sprocket
 from the doner car and Toyota made no provision cam sensor magnet now the question  A. will an epoxied magnet work and B. can some one suggest a si> thanks 
> Duane
> 
> 
The falling edge is after the rising edge, all pulses have a finite 
width (except in quantum mechanics where you can use a Dirac 
aproximation) thus they rise stay high for a while then crash.
microcontrollers have a external  interrupt that can set on the 
rising or falling edge.  determine direction of rotation and make 
settings at the end of physical length of  trigger mechanism.
alex