Microchip Technology Inc

Capacitive Discharge Ignition

The two-wheelers industry, comprised of scooters, motorcycles and mopeds, commonly use an engine ignition system based on capacitive discharge method. The Capacitive Discharge Ignition (CDI) system, when released as a high-voltage pulse via a step-up transformer to a spark plug, utilizes the energy transferred from magneto to a storage capacitor which ignites the fuel mixture inside the cylinder. The digital CDI allows the user to monitor the speed of the engine and to calculate the accurate timing for the spark which increase engine efficiency, saves energy and reduces emissions.

Design Considerations
  • Robust, general purpose microcontroller family with a small footprint
  • PIC16 and PIC18 microcontrollers enable a broad array of on-chip peripherals which provide the system designer with flexible options for consideration in addressing the requirements of a variable timing CDI system. In such a system, the speed of the engine is monitored electronically with a PIC® microcontroller which also provides accurate timing for the spark. With a PIC microcontroller, the ignition spark can be made to occur anytime for a particular engine speed allowing ignition angle customization for different engine designs, which supports the requirements of improved fuel efficiency and reduced emissions.
  • PIC microcontrollers utilize small footprints coupled with robust design innovations making it possible for the PIC microcontroller-based digital CDI systems be delivered at reduced system costs, without sacrificing performance.
Development Tools