Adafruit PCF8523 Real Time Clock Assembled Breakout Board

PCF8523 RTC breakout with battery backup for timekeeping when main power is removed. Communicates over I2C; operates at 3.3V or 5V supply and logic. Suitable for datalogging, alarms, and clock applications.

VCC
Power pin for the PCF8523 breakout. Adafruit Learn says to power it at the microcontroller logic level.
Type · powerVoltage · 3-5VDC input, same as logic level
GND
Common ground for power and logic.
Type · groundVoltage · 0V
SCL
I2C clock line.
Type · signalVoltage · logic level follows VCC
SDA
I2C data line.
Type · signalVoltage · logic level follows VCC
STEMMA QT
STEMMA QT connector on the STEMMA QT version for I2C/power chaining.
Type · connectorVoltage · carries VCC, GND, SCL, and SDA
SQW
Square-wave output pin when enabled.
Type · signal

Pin	Type	Function	Voltage
VCC	power	Power pin for the PCF8523 breakout. Adafruit Learn says to power it at the microcontroller logic level.	3-5VDC input, same as logic level
GND	ground	Common ground for power and logic.	0V
SCL	signal	I2C clock line.	logic level follows VCC
SDA	signal	I2C data line.	logic level follows VCC
STEMMA QT	connector	STEMMA QT connector on the STEMMA QT version for I2C/power chaining.	carries VCC, GND, SCL, and SDA
SQW	signal	Square-wave output pin when enabled.

RTC & timing

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