The MC68185FNR2 is a Real-Time Clock (RTC) and calendar peripheral manufactured by Freescale Semiconductor (now NXP). It is designed to provide accurate timekeeping, date information, and alarm functionality to embedded systems. The device integrates a crystal oscillator, counters, and control logic to maintain time even when the main system power is off, assuming a backup power source is available.

Applications

• Embedded systems requiring real-time clock functionality.
• Data logging applications where accurate timestamps are critical.
• Industrial control systems.
• Consumer electronics (e.g., set-top boxes, smart appliances).
• Networking equipment.

Features

• Real-time clock/calendar with hundredths of a second resolution.
• Automatic leap year correction.
• Alarm function with programmable interrupt.
• Backup power switch-over for continuous timekeeping.
• Serial interface for communication with a host processor.
• Low power consumption for extended battery life.
• Programmable interrupt output.

Benefits

• Accurate timekeeping ensures reliable data logging and event scheduling.
• Automatic leap year correction simplifies software development.
• Alarm function enables time-based event triggering.
• Backup power capability prevents data loss during power outages.
• Simple serial interface reduces development time and cost.
• Low power consumption extends battery life in portable applications.

Additional Details

The MC68185FNR2 typically operates from a 32.768 kHz crystal. It communicates with a host processor via a serial interface, often SPI or I2C. The device includes registers for storing time, date, alarm settings, and control parameters. The backup power switch-over circuit automatically switches to a backup battery when the main power supply fails, ensuring continuous timekeeping operation. Its primary use is in systems that must maintain an accurate time regardless of the device's primary power state.