An LSI Implementation of a Low Cost Ignition Controller 820251
THIS PAPER WILL DISCUSS the function and implementation of a low cost ignition controller. Rombic (ROM Based Ignition Controller) is a low cost alternative to today's larger electronic systems, Rombic, while designed specifically to address a market for inexpensive four cylinder engine controls, is also capable of controlling larger 6 and 8 cylinder engines. We will be investigating both the implementation of a spark advance system using the Rombic controller and actual LSI implementation of that controller.
The ROM Based Ignition Controller is a digital system which operates in the time domain to generate a desired spark advance, according to the length of a measured reference interval (inverse of rpm). The system utilizes lists of the time value in ROM or PROM. Each list corresponds to the advance vs rpm relationship for a specific vacuum level. This permits a true two dimensional mapping of spark advance as a function of rpm and vacuum.
Rombic is presently implemented in a 2 chip format; a CMOS Control Chip with on board A/D conversion for vacuum, and a standard CMOS ROM. The control chip has been developed using the RCA Automatic Placement and Routing Computer Aided Design System. The capability of computer placement and routing for digital logic circuits allows for quick turnaround of LSI integrated circuits. In addition, recent improvements to the AFAR design system have further streamlined the design cycle for any LSI integrated circuit.