资 源 简 介
The FM32xx is a family of integrated devices thatincludes the most commonly needed funcTIons forprocessor-based systems. Major features includenonvolaTIle memory available in various sizes, low-VDD reset, watchdog TImer, nonvolaTIle event counter,lockable 64-bit serial number area, and generalpurpose comparator that can be used for an earlypower-fail (NMI) interrupt or other purpose. Thefamily operates from 2.7 to 5.5V.The FM32xx family is software and pinoutcompatible with the FM31xx family which alsoincludes a real-time clock. The common featuresallow a system design that easily can be assembledwith or without timekeeping by simply selecting theFM31xx or FM32xx, respectively.Each FM32xx provides nonvolatile RAM available insizes including 4Kb, 16Kb, 64Kb, and 256Kbversions. Fast write speed and unlimited enduranceallow the memory to serve as extra RAM orconventional nonvolatile storage. This memory istruly nonvolatile rather than battery backed.The processor companion includes commonly neededCPU support functions. Supervisory functionsinclude a reset output signal controlled by either alow VDD condition or a watchdog timeout. /RST goesactive when VDD drops below a programmablethreshold and remains active for 100 ms after VDDrises above the trip point. A programmable watchdogtimer runs from 100 ms to 3 seconds. The watchdogtimer is optional, but if enabled it will assert the resetsignal for 100 ms if not restarted by the host beforethe timeout. A flag-bit indicates the source of thereset.A general-purpose comparator compares an externalinput pin to the onboard 1.2V reference. This isuseful for generating an early warning power-failinterrupt (NMI) but can be used for any purpose. Thefamily also includes a programmable 64-bit serialnumber that can be locked making it unalterable.Additionally the FM32xx offers a dual event counterthat tracks the number of rising or falling edgesdetected on dedicated input pins. The counter canoptionally be battery backed and even batteryoperated by attaching a backup power source to theVBAK pin. If VBAK is connected to a battery orcapacitor, then events will be counted even in theabsence of VDD.
