Programmable Timer With Global Reset
Original Publication Date: 1985-Oct-01
Included in the Prior Art Database: 2005-Feb-19
A programmable timer provides carefully timed interrupts to a microprocessor system over a wide time range. If an interrupt is not serviced within a specific time interval, the system is assumed to be hung up and a global reset pulse is generated. A programmable timer indicated generally at 4 (Fig. 1) provides a wide range of interrupt intervals. A microprocessor (not shown) is allowed to select from several input clock frequencies provided on lines 6 and 8 and modified by a frequency reduce counter 10. Two clock frequencies are used, requiring a one-bit latch, here called a"slow/ fast select" latch, indicated at 12. Using a greater number of input clocks would require a correspondingly greater number of clock select bits.