Add esp32-ds18b20-example source

.gitignore

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+.clangd/
+build/
+sdkconfig
+sdkconfig.old
+compile_commands.json
+

CMakeLists.txt

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+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(airmon LANGUAGES C)
+
+set(PROJECT_ELF ${project_elf})
+
+# Ignore false clang warnings about `struct foo = { 0 }`
+target_compile_options(${PROJECT_ELF} PRIVATE -Wno-missing-braces -Wmissing-field-initializers)
+

components/esp32-ds18b20/.travis.yml

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+# Build and deploy doxygen documention to GitHub Pages
+sudo: false
+dist: trusty
+
+# Blacklist
+branches:
+  only:
+    - master
+
+# Environment variables
+env:
+  global:
+    - GH_REPO_REF: github.com/DavidAntliff/esp32-ds18b20.git
+
+# Install dependencies
+addons:
+  apt:
+    packages:
+      - doxygen
+      - doxygen-doc
+      - doxygen-latex
+      - doxygen-gui
+      - graphviz
+
+# Build the docs
+script:
+  - cd doc
+  - doxygen
+
+# Deploy using Travis-CI/GitHub Pages integration support
+deploy:
+  provider: pages
+  skip-cleanup: true
+  local-dir: doc/html
+  github-token: $GITHUB_TOKEN
+  on:
+    branch: master
+  target-branch: gh-pages
+

components/esp32-ds18b20/CMakeLists.txt

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+set(COMPONENT_ADD_INCLUDEDIRS include)
+set(COMPONENT_SRCS "ds18b20.c")
+set(COMPONENT_PRIV_REQUIRES "esp32-owb")
+register_component()
+
+

components/esp32-ds18b20/LICENSE

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+MIT License
+
+Copyright (c) 2017 David Antliff
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

components/esp32-ds18b20/README.md

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+# esp32-ds18b20
+
+## Introduction
+
+This is a ESP32-compatible C component for the Maxim Integrated DS18B20 Programmable Resolution 1-Wire Digital
+Thermometer device.
+
+It supports multiple devices on the same 1-Wire bus.
+
+It is written and tested for v2.1, v3.0-3.3 and v4.1-beta1 of the [ESP-IDF](https://github.com/espressif/esp-idf) 
+environment, using the xtensa-esp32-elf toolchain (gcc version 5.2.0).
+
+## Dependencies
+
+Requires [esp32-owb](https://github.com/DavidAntliff/esp32-owb).
+
+## Example
+
+See [esp32-ds18b20-example](https://github.com/DavidAntliff/esp32-ds18b20-example) for an example that supports single
+and multiple devices on a single bus.
+
+## Features
+
+In cooperation with the underlying esp32-owb component, this component includes:
+
+ * External power supply mode.
+ * Parasitic power mode (VDD and GND connected) - see notes below.
+ * Static (stack-based) or dynamic (malloc-based) memory model.
+ * No globals - support any number of DS18B20 devices on any number of 1-Wire buses simultaneously.
+ * 1-Wire device detection and validation, including search for multiple devices on a single bus.
+ * Addressing optimisation for a single (solo) device on a bus.
+ * CRC checks on temperature data.
+ * Programmable temperature measurement resolution (9, 10, 11 or 12-bit resolution).
+ * Temperature conversion and retrieval.
+ * Separation of conversion and temperature retrieval to allow for simultaneous conversion across multiple devices.
+
+## Parasitic Power Mode
+
+Consult the [datasheet](http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf) for more detailed information about
+Parasitic Power mode.
+
+Parasitic power operation can be detected by `ds18b20_check_for_parasite_power()` followed by a call to
+`owb_use_parasitic_power()`, or simply set explicitly by a call to the latter.
+
+This library has been tested on the ESP32 with two parasitic-power configurations, with two DS18B20 devices at 3.3V:
+
+1. Disconnect power to each device's VDD pin, and connect that pin to GND for each device. Power is supplied to
+   each device through the OWB data line.
+2. Connect the OWB data line to VCC via a P-channel MOSFET (e.g. BS250) and current-limiting resistor (e.g. 270 Ohm).
+   Ensure your code calls `owb_use_strong_pullup_gpio()` with the GPIO connected to the MOSFET Gate. The GPIO will go
+   high during temperature conversion, turning on the MOSFET and providing power from VCC to each device through the OWB
+   data line.
+
+If you set up configuration 1 and do not see CRC errors, but you get incorrect temperature readings around 80 - 85 
+degrees C, then it is likely that your DS18B20 devices are running out of power during the temperature conversion. In 
+this case, consider reducing the value of the pull-up resistor. For example, I have had success obtaining correct
+conversions from two parasitic DS18B20 devices by replacing the 4k7 Ohm pull-up resistor with a 1 kOhm resistor.
+
+Alternatively, consider using configuration 2.
+
+Note that use of parasitic power mode disables the ability for devices on the bus to signal that an operation has 
+completed. This means that DS18B20 devices in parasitic power mode are not able to communicate when they have completed
+a temperature conversion. In this mode, a delay for a pre-calculated duration occurs, and then the conversion result is
+read from the device(s). *If your ESP32 is not running on the correct clock rate, this duration may be too short!*  
+
+## Documentation
+
+Automatically generated API documentation (doxygen) is available [here](https://davidantliff.github.io/esp32-ds18b20/index.html).
+
+## Source Code
+
+The source is available from [GitHub](https://www.github.com/DavidAntliff/esp32-ds18b20).
+
+## License
+
+The code in this project is licensed under the MIT license - see LICENSE for details.
+
+## Links
+
+ * [DS18B20 Datasheet](http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf)
+ * [1-Wire Communication Through Software](https://www.maximintegrated.com/en/app-notes/index.mvp/id/126)
+ * [1-Wire Search Algorithm](https://www.maximintegrated.com/en/app-notes/index.mvp/id/187)
+ * [Espressif IoT Development Framework for ESP32](https://github.com/espressif/esp-idf)
+
+## Acknowledgements
+
+Parts of this code are based on references provided to the public domain by Maxim Integrated.
+
+"1-Wire" is a registered trademark of Maxim Integrated.
+
+## Roadmap
+
+The following features are anticipated but not yet implemented:
+
+ * Concurrency support (multiple tasks accessing devices on the same bus).
+ * Alarm support.
+ * EEPROM support.
+ * Parasitic power support.

components/esp32-ds18b20/component.mk

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+# Use defaults

components/esp32-ds18b20/doc/.gitignore

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+html/
+latex/
+