Real Time Alarm Clock(RTC) PCF8523

File:TArduinoRTCPFC8523.png

Summary

Provides real-time clock functionality with alarms, timers, and power management using the PCF8523 RTC chip over I²C.

Description

The Real Time Alarm Clock (RTC) PCF8523 component interfaces with the NXP PCF8523 real-time clock via the I²C bus. It supports accurate timekeeping, programmable alarms, timers, power management, and watchdog functionality.

This component is useful for:

Projects requiring time-based events (alarms, scheduled actions)

Low-power applications using battery backup and power switching

Systems that need periodic interrupts or watchdog timers

Embedded systems requiring robust calendar timekeeping with correction offsets

Diagram:

Categories

• Category Generators/Date/Time – Hardware and IC-based time generators.
• Category Date/Time – Timekeeping and scheduling components.
• Category Data Sources/Date/Time – I²C RTC data sources.

Properties

• Address – I²C address of the PCF8523 device.
• Alarm – Alarm configuration:
  • Day – Integer day value.
  • Hour – Integer hour value.
  • Minute – Integer minute value.
  • Week Day – Integer weekday value.
  • Interrupt Enabled – Boolean; enables or disables alarm interrupt.
• Capacitor12_6 – Boolean; enables internal 12.6 pF oscillator load capacitor.
• Clock Out – Clock output configuration:
  • Enabled – Boolean; enable/disable clock output.
  • Frequency – Enum (pcf23co32768Hz, pcf23co16384Hz, pcf23co8192Hz, pcf23co4096Hz, pcf23co1024Hz, pcf23co32Hz).
• Elements – Date/Time initialization values: Set Second, Minute, Hour, Day, Week Day, Month, Year.
• Offset – Calibration correction:
  • Correction Interrupt Enabled – Boolean.
  • Per Minute – Boolean; applies offset once per minute.
  • Value – Integer correction value.
• Power Management – Battery and power switching behavior:
  • Battery Low Interrupt Enabled – Boolean.
  • Power Switch Interrupt Enabled – Boolean.
  • Switch Mode – Enum (rtc23psmStandard, rtc23psmDirect, rtc23psmSinglePower).
• Second And Timer A – Timer/clock configuration:
  • Clock Frequency – Enum (pcf23tAuto, pcf23t4096Hz, pcf23t64Hz, pcf23t1Hz, pcf23t1_60th_Hz, pcf23t1_3600th_Hz).
  • Enabled – Boolean.
  • Interrupt Enabled – Boolean.
  • Is Watchdog – Boolean; enables watchdog functionality.
  • Period – Timer period in seconds.
  • Pulse Interrupt Enabled – Boolean.
  • Second Interrupt Enabled – Boolean.
• Timer B – Secondary timer configuration:
  • Clock Frequency – Enum (pcf23tAuto, pcf23t4096Hz, pcf23t64Hz, pcf23t1Hz, pcf23t1_60th_Hz, pcf23t1_3600th_Hz).
  • Enabled – Boolean.
  • Interrupt Enabled – Boolean.
  • Low Pulse Width – Timer B pulse width in milliseconds (default 46.875 ms).
  • Period – Timer period in seconds.
  • Pulse Interrupt Enabled – Boolean.

Pins

• Clock – External clock input.
• Set – Date/Time input used to set the RTC.

Outputs:

• Second and Timer A –
  • Second Clock (Clock) – Provides a 1-second tick.
  • Timer (Clock) – Output from Timer A.
• Timer B (Clock) – Output from Timer B.
• Power Management –
  • Battery Low (Boolean) – Indicates low battery condition.
  • Power Switched (Clock) – Indicates power switching events.
• Out – Date/Time output from the RTC.
• Control (I²C) – Communication interface with the PCF8523.
• Integrity Compromised (Boolean) – Signals that clock integrity may be lost (e.g., power loss).
• Alarm (Clock) – Alarm interrupt output.