init

.github/ISSUE_TEMPLATE.md

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+Thank you for opening an issue on an Adafruit Arduino library repository.  To
+improve the speed of resolution please review the following guidelines and
+common troubleshooting steps below before creating the issue:
+
+- **Do not use GitHub issues for troubleshooting projects and issues.**  Instead use
+  the forums at http://forums.adafruit.com to ask questions and troubleshoot why
+  something isn't working as expected.  In many cases the problem is a common issue
+  that you will more quickly receive help from the forum community.  GitHub issues
+  are meant for known defects in the code.  If you don't know if there is a defect
+  in the code then start with troubleshooting on the forum first.
+
+- **If following a tutorial or guide be sure you didn't miss a step.** Carefully
+  check all of the steps and commands to run have been followed.  Consult the
+  forum if you're unsure or have questions about steps in a guide/tutorial.
+
+- **For Arduino projects check these very common issues to ensure they don't apply**:
+
+  - For uploading sketches or communicating with the board make sure you're using
+    a **USB data cable** and **not** a **USB charge-only cable**.  It is sometimes
+    very hard to tell the difference between a data and charge cable!  Try using the
+    cable with other devices or swapping to another cable to confirm it is not
+    the problem.
+
+  - **Be sure you are supplying adequate power to the board.**  Check the specs of
+    your board and plug in an external power supply.  In many cases just
+    plugging a board into your computer is not enough to power it and other
+    peripherals.
+
+  - **Double check all soldering joints and connections.**  Flakey connections
+    cause many mysterious problems.  See the [guide to excellent soldering](https://learn.adafruit.com/adafruit-guide-excellent-soldering/tools) for examples of good solder joints.
+
+  - **Ensure you are using an official Arduino or Adafruit board.** We can't
+    guarantee a clone board will have the same functionality and work as expected
+    with this code and don't support them.
+
+If you're sure this issue is a defect in the code and checked the steps above
+please fill in the following fields to provide enough troubleshooting information.
+You may delete the guideline and text above to just leave the following details:
+
+- Arduino board:  **INSERT ARDUINO BOARD NAME/TYPE HERE**
+
+- Arduino IDE version (found in Arduino -> About Arduino menu):  **INSERT ARDUINO
+  VERSION HERE**
+
+- List the steps to reproduce the problem below (if possible attach a sketch or
+  copy the sketch code in too): **LIST REPRO STEPS BELOW**

.github/PULL_REQUEST_TEMPLATE.md

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+Thank you for creating a pull request to contribute to Adafruit's GitHub code!
+Before you open the request please review the following guidelines and tips to
+help it be more easily integrated:
+
+- **Describe the scope of your change--i.e. what the change does and what parts
+  of the code were modified.**  This will help us understand any risks of integrating
+  the code.
+
+- **Describe any known limitations with your change.**  For example if the change
+  doesn't apply to a supported platform of the library please mention it.
+
+- **Please run any tests or examples that can exercise your modified code.**  We
+  strive to not break users of the code and running tests/examples helps with this
+  process.
+
+Thank you again for contributing!  We will try to test and integrate the change
+as soon as we can, but be aware we have many GitHub repositories to manage and
+can't immediately respond to every request.  There is no need to bump or check in
+on a pull request (it will clutter the discussion of the request).
+
+Also don't be worried if the request is closed or not integrated--sometimes the
+priorities of Adafruit's GitHub code (education, ease of use) might not match the
+priorities of the pull request.  Don't fret, the open source community thrives on
+forks and GitHub makes it easy to keep your changes in a forked repo.
+
+After reviewing the guidelines above you can delete this text from the pull request.

.github/workflows/githubci.yml

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+name: Arduino Library CI
+
+on: [pull_request, push, repository_dispatch]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    
+    steps:
+    - uses: actions/setup-python@v1
+      with:
+        python-version: '3.x'
+    - uses: actions/checkout@v2
+    - uses: actions/checkout@v2
+      with:
+         repository: adafruit/ci-arduino
+         path: ci
+
+    - name: pre-install
+      run: bash ci/actions_install.sh
+
+    - name: test platforms
+      run: python3 ci/build_platform.py main_platforms
+
+    - name: clang
+      run: python3 ci/run-clang-format.py -e "ci/*" -e "bin/*" -r . 
+
+    - name: doxygen
+      env:
+        GH_REPO_TOKEN: ${{ secrets.GH_REPO_TOKEN }}
+        PRETTYNAME : "Adafruit PCF8574 Arduino Library"
+      run: bash ci/doxy_gen_and_deploy.sh

.gitignore

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+Doxyfile
+.vscode/
+html/
+.DS_Store

Adafruit_PCF8574.cpp

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+/*!
+ *  @file Adafruit_PCF8574.cpp
+ *
+ *  @mainpage Adafruit PCF8574 I2C Potentiometer
+ *
+ *  @section intro_sec Introduction
+ *
+ * 	I2C Driver for the NXP PCF8574 I2C GPIO expander
+ *
+ * 	This is a library for the Adafruit PCF8574 breakout:
+ * 	http://www.adafruit.com/products
+ *
+ * 	Adafruit invests time and resources providing this open source code,
+ *  please support Adafruit and open-source hardware by purchasing products from
+ * 	Adafruit!
+ *
+ *  @section dependencies Dependencies
+ *
+ *  This library depends on the Adafruit BusIO library
+ *
+ *  @section author Author
+ *
+ *  ladyada for Adafruit Industries
+ *
+ * 	@section license License
+ *
+ * 	BSD (see license.txt)
+ *
+ * 	@section  HISTORY
+ *
+ *     v1.0 - First release
+ */
+
+#include "Adafruit_PCF8574.h"
+
+/*!
+ *    @brief  Instantiates a new PCF8574 class
+ */
+Adafruit_PCF8574::Adafruit_PCF8574(void) {}
+
+/*!
+ *    @brief  Sets up the hardware and initializes I2C
+ *    @param  i2c_address
+ *            The I2C address to be used.
+ *    @param  wire
+ *            The Wire object to be used for I2C connections.
+ *    @return True if initialization was successful, otherwise false.
+ */
+bool Adafruit_PCF8574::begin(uint8_t i2c_address, TwoWire *wire) {
+  delete(i2c_dev);
+
+  i2c_dev = new Adafruit_I2CDevice(i2c_address, wire);
+
+  if (!i2c_dev->begin()) {
+    return false;
+  }
+
+  return true;
+}
+
+
+bool Adafruit_PCF8574::digitalWriteByte(uint8_t d) {
+  _writebuf = d;
+  return i2c_dev->write(&_writebuf, 1);
+}
+
+uint8_t Adafruit_PCF8574::digitalReadByte(void) {
+  i2c_dev->read(&_readbuf, 1);
+  return _readbuf;
+}
+
+bool Adafruit_PCF8574::digitalWrite(uint8_t pinnum, bool val) {
+  if (val) {
+    _writebuf |= 1 << pinnum;
+  } else {
+    _writebuf &= ~(1 << pinnum);
+  }
+  return i2c_dev->write(&_writebuf, 1);
+}
+
+
+bool Adafruit_PCF8574::pinMode(uint8_t pinnum, uint8_t val) {
+  if ((val == INPUT) || (val == INPUT_PULLUP)) {
+    _writebuf |= 1 << pinnum;
+  } else {
+    _writebuf &= ~(1 << pinnum);
+  }
+  return i2c_dev->write(&_writebuf, 1);
+}
+
+
+bool Adafruit_PCF8574::digitalRead(uint8_t pinnum) {
+  i2c_dev->read(&_readbuf, 1);
+  return (_readbuf >> pinnum) & 0x1;
+}

Adafruit_PCF8574.h

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+/*!
+ *  @file Adafruit_PCF8574.h
+ *
+ * 	I2C Driver for PCF8574 I2C GPIO expander
+ *
+ * 	This is a library for the Adafruit PCF8574 breakout:
+ * 	http://www.adafruit.com/products
+ *
+ * 	Adafruit invests time and resources providing this open source code,
+ *  please support Adafruit and open-source hardware by purchasing products from
+ * 	Adafruit!
+ *
+ *
+ *	BSD license (see license.txt)
+ */
+
+#ifndef _ADAFRUIT_PCF8574_H
+#define _ADAFRUIT_PCF8574_H
+
+#include "Arduino.h"
+#include <Wire.h>
+
+#include <Adafruit_BusIO_Register.h>
+#include <Adafruit_I2CDevice.h>
+
+#define PCF8574_I2CADDR_DEFAULT 0x20 ///< DS3502 default I2C address
+
+
+/*!
+ *    @brief  Class that stores state and functions for interacting with
+ *            the PCF8574 I2C Expander
+ */
+class Adafruit_PCF8574 {
+public:
+  Adafruit_PCF8574();
+  bool begin(uint8_t i2c_addr = PCF8574_I2CADDR_DEFAULT, TwoWire *wire = &Wire);
+
+  bool digitalWriteByte(uint8_t d);
+  bool digitalWrite(uint8_t pinnum, bool val);
+  uint8_t digitalReadByte(void);
+  bool digitalRead(uint8_t pinnum);
+  bool pinMode(uint8_t pinnum, uint8_t val);
+
+private:
+  uint8_t _readbuf = 0, _writebuf = 0;
+
+  Adafruit_I2CDevice *i2c_dev;
+};
+
+#endif

README.md

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+# Adafruit PCF8574 [![Build Status](https://github.com/adafruit/Adafruit_PCF8574/workflows/Arduino%20Library%20CI/badge.svg)](https://github.com/adafruit/Adafruit_PCF8574/actions)
+
+<a href="https://www.adafruit.com/products/"><img src="assets/board.jpg?raw=true" width="500px"></a>
+
+This is the Adafruit PCF8574 I2C GPIO Exapnder library
+
+Tested and works great with the Adafruit PCF8574 Breakout Board 
+* http://www.adafruit.com/products/
+
+This chip uses I2C to communicate, 2 pins are required to interface
+
+Adafruit invests time and resources providing this open source code, please support Adafruit and open-source hardware by purchasing products from Adafruit!
+
+# Dependencies
+ * [Adafruit BusIO](https://github.com/adafruit/Adafruit_BusIO)
+
+r Contributing
+
+Contributions are welcome! Please read our [Code of Conduct](https://github.com/adafruit/Adafruit_DS3502/blob/master/CODE_OF_CONDUCT.md>)
+before contributing to help this project stay welcoming.
+
+## Documentation and doxygen
+Documentation is produced by doxygen. Contributions should include documentation for any new code added.
+
+Some examples of how to use doxygen can be found in these guide pages:
+
+https://learn.adafruit.com/the-well-automated-arduino-library/doxygen
+
+https://learn.adafruit.com/the-well-automated-arduino-library/doxygen-tips
+
+Written by ladyada for Adafruit Industries.
+BSD license, check license.txt for more information
+All text above must be included in any redistribution
+
+To install, use the Arduino Library Manager and search for "Adafruit PCF8574" and install the library.

code-of-conduct.md

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+# Adafruit Community Code of Conduct
+
+## Our Pledge
+
+In the interest of fostering an open and welcoming environment, we as
+contributors and leaders pledge to making participation in our project and
+our community a harassment-free experience for everyone, regardless of age, body
+size, disability, ethnicity, gender identity and expression, level or type of
+experience, education, socio-economic status, nationality, personal appearance,
+race, religion, or sexual identity and orientation.
+
+## Our Standards
+
+We are committed to providing a friendly, safe and welcoming environment for
+all.
+
+Examples of behavior that contributes to creating a positive environment
+include:
+
+* Be kind and courteous to others
+* Using welcoming and inclusive language
+* Being respectful of differing viewpoints and experiences
+* Collaborating with other community members
+* Gracefully accepting constructive criticism
+* Focusing on what is best for the community
+* Showing empathy towards other community members
+
+Examples of unacceptable behavior by participants include:
+
+* The use of sexualized language or imagery and sexual attention or advances
+* The use of inappropriate images, including in a community member's avatar
+* The use of inappropriate language, including in a community member's nickname
+* Any spamming, flaming, baiting or other attention-stealing behavior
+* Excessive or unwelcome helping; answering outside the scope of the question
+  asked
+* Trolling, insulting/derogatory comments, and personal or political attacks
+* Public or private harassment
+* Publishing others' private information, such as a physical or electronic
+  address, without explicit permission
+* Other conduct which could reasonably be considered inappropriate
+
+The goal of the standards and moderation guidelines outlined here is to build
+and maintain a respectful community. We ask that you don’t just aim to be
+"technically unimpeachable", but rather try to be your best self. 
+
+We value many things beyond technical expertise, including collaboration and
+supporting others within our community. Providing a positive experience for
+other community members can have a much more significant impact than simply
+providing the correct answer.
+
+## Our Responsibilities
+
+Project leaders are responsible for clarifying the standards of acceptable
+behavior and are expected to take appropriate and fair corrective action in
+response to any instances of unacceptable behavior.
+
+Project leaders have the right and responsibility to remove, edit, or
+reject messages, comments, commits, code, issues, and other contributions
+that are not aligned to this Code of Conduct, or to ban temporarily or
+permanently any community member for other behaviors that they deem
+inappropriate, threatening, offensive, or harmful.
+
+## Moderation
+
+Instances of behaviors that violate the Adafruit Community Code of Conduct
+may be reported by any member of the community. Community members are
+encouraged to report these situations, including situations they witness
+involving other community members.
+
+You may report in the following ways:
+
+In any situation, you may send an email to <support@adafruit.com>.
+
+On the Adafruit Discord, you may send an open message from any channel
+to all Community Helpers by tagging @community helpers. You may also send an
+open message from any channel, or a direct message to @kattni#1507,
+@tannewt#4653, @Dan Halbert#1614, @cater#2442, @sommersoft#0222, or
+@Andon#8175.
+
+Email and direct message reports will be kept confidential.
+
+In situations on Discord where the issue is particularly egregious, possibly
+illegal, requires immediate action, or violates the Discord terms of service,
+you should also report the message directly to Discord.
+
+These are the steps for upholding our community’s standards of conduct.
+
+1. Any member of the community may report any situation that violates the
+Adafruit Community Code of Conduct. All reports will be reviewed and
+investigated.
+2. If the behavior is an egregious violation, the community member who
+committed the violation may be banned immediately, without warning.
+3. Otherwise, moderators will first respond to such behavior with a warning.
+4. Moderators follow a soft "three strikes" policy - the community member may
+be given another chance, if they are receptive to the warning and change their
+behavior.
+5. If the community member is unreceptive or unreasonable when warned by a
+moderator, or the warning goes unheeded, they may be banned for a first or
+second offense. Repeated offenses will result in the community member being
+banned.
+
+## Scope
+
+This Code of Conduct and the enforcement policies listed above apply to all
+Adafruit Community venues. This includes but is not limited to any community
+spaces (both public and private), the entire Adafruit Discord server, and
+Adafruit GitHub repositories. Examples of Adafruit Community spaces include
+but are not limited to meet-ups, audio chats on the Adafruit Discord, or
+interaction at a conference.
+
+This Code of Conduct applies both within project spaces and in public spaces
+when an individual is representing the project or its community. As a community
+member, you are representing our community, and are expected to behave
+accordingly.
+
+## Attribution
+
+This Code of Conduct is adapted from the [Contributor Covenant][homepage],
+version 1.4, available at
+<https://www.contributor-covenant.org/version/1/4/code-of-conduct.html>,
+and the [Rust Code of Conduct](https://www.rust-lang.org/en-US/conduct.html).
+
+For other projects adopting the Adafruit Community Code of
+Conduct, please contact the maintainers of those projects for enforcement.
+If you wish to use this code of conduct for your own project, consider
+explicitly mentioning your moderation policy or making a copy with your
+own moderation policy so as to avoid confusion.

library.properties

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+name=Adafruit PCF8574
+version=1.0.0
+author=Adafruit
+maintainer=Adafruit <info@adafruit.com>
+sentence=Arduino library for the PCF8574 I2C GPIO expander Adafruit shop
+paragraph=Arduino library for the PCF8574 I2C GPIO expander Adafruit shop
+category=Device Control
+url=https://github.com/adafruit/Adafruit_PCF8574
+architectures=*
+depends=Adafruit BusIO

license.txt

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+Software License Agreement (BSD License)
+
+Copyright (c) 2020 Bryan Siepert for Adafruit Industries
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+1. Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+2. Redistributions in binary form must reproduce the above copyright
+notice, this list of conditions and the following disclaimer in the
+documentation and/or other materials provided with the distribution.
+3. Neither the name of the copyright holders nor the
+names of its contributors may be used to endorse or promote products
+derived from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ''AS IS'' AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.