Realtime Clock Module Programmable for Different System Clock Inputs
Original Publication Date: 1983-Aug-01
Included in the Prior Art Database: 2005-Feb-07
This article describes a realtime clock module which is universal in the sense that different system clock input frequencies can be used to drive the clock module. Compare operations are performed on outputs from system clock-driven counters and processor-loaded registers. Conventional realtime clock modules require a system clock input having a specific frequency. The clock module shown in the drawing can be driven using any known system clock input frequency within hardware limitations, to be described. Referring to the drawing, a system clock signal is applied to an N-bit counter 10. The system clock frequency is shown as X hertz, but would probably be in the kilohertz to low megahertz range. The counter output is applied in parallel to a compare circuit 12.