Design with Adafruit PCF8523 RTC in Cirkit DesignerThe Adafruit PCF8523 RTC is a Real Time Clock (RTC) module that offers precise timekeeping capabilities. It is designed to maintain accurate time with the help of a built-in crystal oscillator and can continue to keep time with a backup battery even when the main power supply is disconnected. This component is ideal for a variety of applications, including data loggers, alarm systems, and other time-sensitive projects.
Common applications and use cases:
This circuit is an Arduino-based real-time clock and display system. It uses an Arduino UNO to interface with a DS1307 RTC module for timekeeping and a 20x4 I2C LCD to display the current time and date. Additionally, a PCF8574 IO Expansion Board is used to extend the I2C bus for additional I/O operations.
Open Project in Cirkit Designer
This circuit integrates two RTC DS3231 real-time clock modules with a Glyph C3 microcontroller. The RTC modules are connected to the microcontroller via I2C communication protocol, using the SCL and SDA lines for clock and data respectively. Both RTC modules and the microcontroller share a common power supply (3V3) and ground (GND), indicating that they operate at the same voltage level.
Open Project in Cirkit Designer
This circuit features an Arduino UNO connected to a DS1307 Real Time Clock (RTC) module for timekeeping and a red LED with a series resistor for indication purposes. The Arduino communicates with the RTC via I2C (using A4 and A5 pins for SDA and SCL, respectively), and controls the LED connected to digital pin D8 through a 330-ohm resistor. The embedded code sets the RTC time, checks the current time, and turns the LED on or off based on the specified time condition (between 11:00 AM and 11:43 AM).
Open Project in Cirkit Designer
This circuit connects an Arduino UNO microcontroller with a DS3231 Real Time Clock (RTC) module. The Arduino provides 5V power and ground to the RTC and communicates with it via the I2C protocol using the A4 (SDA) and A5 (SCL) pins. The embedded code on the Arduino is used to initialize the RTC, check for power loss, set the current time if needed, and periodically read and print the current time to the serial monitor.
Open Project in Cirkit Designer| Pin Number | Name | Description |
|---|---|---|
| 1 | VCC | Power supply (1.8V to 5.5V) |
| 2 | GND | Ground connection |
| 3 | SDA | I2C Data Line |
| 4 | SCL | I2C Clock Line |
| 5 | INT | Interrupt output (active low) |
| 6 | CLKOUT | Clock output for peripheral devices |
#include <Wire.h>
#include "RTClib.h"
RTC_PCF8523 rtc;
void setup() {
Wire.begin();
Serial.begin(9600);
// Check if the RTC is connected correctly
if (!rtc.begin()) {
Serial.println("Couldn't find RTC");
while (1);
}
// Check if the RTC has lost power and if so, set the time
if (!rtc.initialized() || rtc.lostPower()) {
Serial.println("RTC is NOT initialized, let's set the time!");
// This line sets the RTC to the date & time this sketch was compiled
rtc.adjust(DateTime(F(__DATE__), F(__TIME__)));
}
}
void loop() {
DateTime now = rtc.now();
// Print the current date and time
Serial.print(now.year(), DEC);
Serial.print('/');
Serial.print(now.month(), DEC);
Serial.print('/');
Serial.print(now.day(), DEC);
Serial.print(" ");
Serial.print(now.hour(), DEC);
Serial.print(':');
Serial.print(now.minute(), DEC);
Serial.print(':');
Serial.print(now.second(), DEC);
Serial.println();
// Wait for a second
delay(1000);
}
Q: Can the PCF8523 RTC module be used with a 3.3V system? A: Yes, the module can operate from 1.8V to 5.5V, making it suitable for both 3.3V and 5V systems.
Q: How long will the backup battery last? A: The battery life depends on the quality of the battery and the environmental conditions but typically lasts for a few years.
Q: Is it necessary to use an external crystal with the PCF8523 RTC? A: No, the PCF8523 has an integrated crystal oscillator that provides accurate timekeeping.