Yamaha FZR400 1988-1989 Service Manual page 307

IGNITION SYSTEM (ELECII
DIGITAL IGNITION CONTROL SYSTEM
DESCRIPTION
The electronic ignition that sparks the engine is
computer controlled and operated by the digital
microprocessor. It has a pre-programed ignition
advance curve.
This programed advance curve closely matches
the spark timing to the engine's ignition require-
ments. Only one pickup coil is needed to meet
the requirements of the digital ignitor unit.
T h e d i g i t a l i g n i t o r a l s o i n c l u d e s t h e c o n t r o l
unit for the electric fuel pump.
Pickup coil
Wave-shape shaping circuit
Edge detection circuit
Latch circuit
Microprocessor
Free-running counter
Comparison circuit
Flip-flop circuit
Driving circuit
Ignition coil
Digital ignitor unit
OPERATION
The following operations are digitally-performed
by signal from the pickup coil signal:
1. Determing proper ignition timing.
2. Sensing the engine revolution speed.
3. Determing timing for switching on ignition
coil (duty control).
4. Increasing ignition coil primary current for
starting the engine.
5. Sensing engine stall.
6. Preventing over-revolution of the engine.
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