Haltech E6K - Manual (Page 132)

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APPENDIX E TRIGGER INTERFACE
Interfacing the E6K with your particular trigger system may be fairly straightforward or it
may be complicated. The variety of trigger designs available is the primary source of
complication. This appendix contains a lot of useful information about the different
approaches to trigger design and is essential information to anyone installing an E6K.
E.1 The Input Trigger
The E6K ECU has been designed to trigger from either a square wave signal that varies from
a ‘low’ of zero volts (ground) to a voltage between 5 and 15 volts or from a magnetic
inductive (reluctor) signal in conjunction with the internal reluctor adaptor or an optional
external reluctor adaptor. A reluctor adaptor converts the sine-like wave signal from the
reluctor sensor to a square wave signal. The actual value of this ‘high’ voltage is not
important because it is the transition from ‘low’ to ‘high’, or ‘high’ to ‘low’, that is used to
trigger the E6K ECU. This transition is referred to as the Trigger Edge and will be shown in
the following illustrations as an upward or downward facing arrow. An upward facing arrow
would indicate that the trigger edge is the transition from low to high and this is called a
Rising Edge
trigger. If the trigger edge occurs on the transition from high to low, it will be
shown as a downward facing arrow, and would be called a falling edge trigger. See Figure
E.1.
Figure E.1
In order for the E6K to operate correctly a trigger edge must be generated for each spark. This
edge must occur a fixed number of degrees before top dead centre (BTDC) and must not
change. The position of the trigger is given in crankshaft degrees and is called Trigger Angle.
In addition there should not be any variation in the trigger angle between cylinders. The E6K
can be set by the user to have its trigger edge occur between 60° and 100° BTDC.
In the example shown in figure E.2a the trigger occurs on a rising edge at 70° BTDC. The
second transition, from high to low, could occur any time after the rising edge. In some
installations the second transition will coincide with 10° BTDC or TDC itself, or it could
happen as close as a few degrees after the trigger edge. This second edge will have no effect
on the correct operation of the E6K ECU. It is only the position of the triggering edge that is
of importance.