boards/shields/adafruit_pcf8523/doc/index.rst
.. _adafruit_pcf8523:
Adafruit PCF8523 Shield #######################
Overview
The Adafruit PCF8523 Real Time Clock Shield_ features
an NXP PCF8523 Real-Time clock_ and two Qwiic connectors.
It has a CR1220 3 Volt back-up coin-cell battery.
.. figure:: adafruit_pcf8523.webp :align: center :alt: Adafruit PCF8523 Shield
Adafruit PCF8523 Shield (Credit: Adafruit)
Requirements
This shield can be used with boards which provide an I2C connector, for
example STEMMA QT or Qwiic connectors.
The target board must define a zephyr_i2c node label.
See :ref:shields for more details.
+--------------+----------------------------------------------------------+ | Shield Pin | Function | +==============+==========================================================+ | SDA | PCF8523 I2C SDA. Also connected to the Qwiic connector. | +--------------+----------------------------------------------------------+ | SCL | PCF8523 I2C SCL. Also connected to the Qwiic connector. | +--------------+----------------------------------------------------------+ | SQW | PCF8523 INT/CLK interrupt output or square wave output | +--------------+----------------------------------------------------------+
To use the interrupt output from the PCF8523, you need to connect a wire from
the shield SQW output to a suitable GPIO on your microcontroller board, and to
modify the devicetree settings. See :dtcompatible:nxp,pcf8523 for options.
Programming
Set --shield adafruit_pcf8523 when you invoke west build. For example
when running the :zephyr:code-sample:rtc sample:
.. zephyr-app-commands:: :zephyr-app: samples/drivers/rtc :board: adafruit_qt_py_rp2040 :shield: adafruit_pcf8523 :goals: build
.. _Adafruit PCF8523 Real Time Clock Shield: https://learn.adafruit.com/adafruit-pcf8523-real-time-clock
.. _NXP PCF8523 Real-Time clock: https://www.nxp.com/products/analog-and-mixed-signal/real-time-clocks/100-na-real-time-clock-calendar-with-battery-backup:PCF8523