DS80C320-MCG Datasheet, PDF (5/175 Pages) Dallas Semiconductor – High-Speed Microcontroller User Guide

High-Speed Microcontroller User’s Guide
POWER MONITOR
Some members of the High-Speed Microcontroller family incorporate a band-gap reference and analog
circuitry to monitor the power supply conditions. V_CC begins to drop out of tolerance, the Power Monitor
will issue an optional early warning Power-fail interrupt. If power continues to fall, the Power Monitor
will invoke a reset condition. This will remain until power returns to normal operating voltage. The
Power Monitor also functions on power-up, holding the microcontroller in a reset state until power is
stable.
INTERRUPTS
The High-Speed Microcontroller is capable of evaluating a number of interrupt sources simultaneously.
Each version of the High-Speed Microcontroller provides a different number of interrupt sources. Each
interrupt has an associated interrupt vector, flag, priority, and enable. These interrupts can be globally
enabled or disabled.
TIMING CONTROL
The High-Speed Microcontroller provides an on-chip oscillator for use with an external crystal. This can
be bypassed by injecting a clock source into the XTAL 1 pin. The clock source is used to create machine
cycle timing (four clocks), ALE, PSEN , Watchdog, Timer, and serial baud rate timing. In addition, some
devices incorporate an on-chip ring oscillator which can be used to provide an approximately 2-4 MHz
clock source.
REAL-TIME CLOCK
The DS87C530 incorporates a real-time clock (RTC), which is accessed via SFR locations. The RTC is
divided into hour, minute, second, and subsecond registers, and also incorporates a 65536 day calendar.
Alarm registers allow the RTC to issue interrupts at a specific time once a day, or as a recurring alarm
every hour, minute or second. An external watch crystal and lithium power source allow the processor to
maintain timekeeping in the absence of V_CC.
FEATURE SUMMARY
The High-Speed Microcontroller family offers a combination of features and peripherals as shown in
Table 3-1. This User’s Guide is designed as a comprehensive guide covering all features available in the
High-Speed Microcontroller family. The designer should investigate the specific data sheet to determine
which features are available on a particular device. Detailed information about newer members of the
product family may be provided in separate documents until they can be assimlilated into the High-Speed
Microcontroller User’s Guide.
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