// RadioHead.h
// Author: Mike McCauley (mikem@airspayce.com) DO NOT CONTACT THE AUTHOR DIRECTLY
// Copyright (C) 2014 Mike McCauley
// $Id: RadioHead.h,v 1.68 2017/11/06 00:04:08 mikem Exp mikem $

/// \mainpage RadioHead Packet Radio library for embedded microprocessors
///
/// This is the RadioHead Packet Radio library for embedded microprocessors.
/// It provides a complete object-oriented library for sending and receiving packetized messages
/// via a variety of common data radios and other transports on a range of embedded microprocessors.
///
/// The version of the package that this documentation refers to can be downloaded 
/// from http://www.airspayce.com/mikem/arduino/RadioHead/RadioHead-1.81.zip
/// You can find the latest version of the documentation at http://www.airspayce.com/mikem/arduino/RadioHead
///
/// You can also find online help and discussion at 
/// http://groups.google.com/group/radiohead-arduino
/// Please use that group for all questions and discussions on this topic. 
/// Do not contact the author directly, unless it is to discuss commercial licensing.
/// Before asking a question or reporting a bug, please read 
/// - http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/How_to_ask_a_software_question
/// - http://www.catb.org/esr/faqs/smart-questions.html
/// - http://www.chiark.greenend.org.uk/~shgtatham/bugs.html
///
/// \par Overview
///
/// RadioHead consists of 2 main sets of classes: Drivers and Managers.
///
/// - Drivers provide low level access to a range of different packet radios and other packetized message transports.
/// - Managers provide high level message sending and receiving facilities for a range of different requirements.
///
/// Every RadioHead program will have an instance of a Driver to provide access to the data radio or transport, 
/// and a Manager that uses that driver to send and receive messages for the application. The programmer is required
/// to instantiate a Driver and a Manager, and to initialise the Manager. Thereafter the facilities of the Manager
/// can be used to send and receive messages.
///
/// It is also possible to use a Driver on its own, without a Manager, although this only allows unaddressed, 
/// unreliable transport via the Driver's facilities.
///
/// In some specialised use cases, it is possible to instantiate more than one Driver and more than one Manager.
///
/// A range of different common embedded microprocessor platforms are supported, allowing your project to run
/// on your choice of processor.
///
/// Example programs are included to show the main modes of use.
///
/// \par Drivers
///
/// The following Drivers are provided:
///
/// - RH_RF22
/// Works with Hope-RF
/// RF22B and RF23B based transceivers, and compatible chips and modules, 
/// including the RFM22B transceiver module such as 
/// this bare module: http://www.sparkfun.com/products/10153
/// and this shield: http://www.sparkfun.com/products/11018 
/// and this board: http://www.anarduino.com/miniwireless
/// and RF23BP modules such as: http://www.anarduino.com/details.jsp?pid=130
/// Supports GFSK, FSK and OOK. Access to other chip 
/// features such as on-chip temperature measurement, analog-digital 
/// converter, transmitter power control etc is also provided.
///
/// - RH_RF24
/// Works with Silicon Labs Si4460/4461/4463/4464 family of transceivers chip, and the equivalent
/// HopeRF RF24/26/27 family of chips and the HopeRF RFM24W/26W/27W modules.
/// Supports GFSK, FSK and OOK. Access to other chip 
/// features such as on-chip temperature measurement, analog-digital 
/// converter, transmitter power control etc is also provided.
///
/// - RH_RF69 
/// Works with Hope-RF
/// RF69B based radio modules, such as the RFM69 module, (as used on the excellent Moteino and Moteino-USB 
/// boards from LowPowerLab http://lowpowerlab.com/moteino/ )
/// and compatible chips and modules such as RFM69W, RFM69HW, RFM69CW, RFM69HCW (Semtech SX1231, SX1231H).
/// Also works with Anarduino MiniWireless -CW and -HW boards http://www.anarduino.com/miniwireless/ including
/// the marvellous high powered MinWireless-HW (with 20dBm output for excellent range).
/// Supports GFSK, FSK.
///
/// - RH_NRF24
/// Works with Nordic nRF24 based 2.4GHz radio modules, such as nRF24L01 and others.
/// Also works with Hope-RF RFM73 
/// and compatible devices (such as BK2423). nRF24L01 and RFM73 can interoperate
/// with each other.
///
/// - RH_NRF905
/// Works with Nordic nRF905 based 433/868/915 MHz radio modules.
///
/// - RH_NRF51
/// Works with Nordic nRF51 compatible 2.4 GHz SoC/devices such as the nRF51822.
/// Also works with Sparkfun nRF52832 breakout board, with Arduino 1.6.13 and
/// Sparkfun nRF52 boards manager 0.2.3
///
/// - RH_RF95
/// Works with Semtech SX1276/77/78/79, Modtronix inAir4 and inAir9,
/// and HopeRF RFM95/96/97/98 and other similar LoRa capable radios.
/// Supports Long Range (LoRa) with spread spectrum frequency hopping, large payloads etc.
/// FSK/GFSK/OOK modes are not (yet) supported.
///
/// - RH_MRF89
/// Works with Microchip MRF89XA and compatible transceivers.
/// and modules such as MRF89XAM9A.
///
/// - RH_CC110
/// Works with Texas Instruments CC110L transceivers and compatible modules such as Anaren AIR BoosterPack 430BOOST-CC110L
///
/// - RH_E32
/// Works with EBYTE E32-TTL-1W serial radio transceivers (and possibly other transceivers in the same family)
///
/// - RH_ASK
/// Works with a range of inexpensive ASK (amplitude shift keying) RF transceivers such as RX-B1 
/// (also known as ST-RX04-ASK) receiver; TX-C1 transmitter and DR3100 transceiver; FS1000A/XY-MK-5V transceiver;
/// HopeRF RFM83C / RFM85. Supports ASK (OOK).
///
/// - RH_Serial
/// Works with RS232, RS422, RS485, RS488 and other point-to-point and multidropped serial connections, 
/// or with TTL serial UARTs such as those on Arduino and many other processors,
/// or with data radios with a 
/// serial port interface. RH_Serial provides packetization and error detection over any hardware or 
/// virtual serial connection. Also builds and runs on Linux and OSX.
///
/// - RH_TCP
/// For use with simulated sketches compiled and running on Linux.
/// Works with tools/etherSimulator.pl to pass messages between simulated sketches, allowing
/// testing of Manager classes on Linux and without need for real radios or other transport hardware.
///
/// - RHEncryptedDriver
/// Adds encryption and decryption to any RadioHead transport driver, using any encrpytion cipher
/// supported by ArduinoLibs Cryptogrphic Library http://rweather.github.io/arduinolibs/crypto.html
///
/// Drivers can be used on their own to provide unaddressed, unreliable datagrams. 
/// All drivers have the same identical API.
/// Or you can use any Driver with any of the Managers described below.
///
/// We welcome contributions of well tested and well documented code to support other transports.
///
/// \par Managers
///
/// The following Mangers are provided:
///
/// - RHDatagram
/// Addressed, unreliable variable length messages, with optional broadcast facilities.
///
/// - RHReliableDatagram
/// Addressed, reliable, retransmitted, acknowledged variable length messages.
///
/// - RHRouter
/// Multi-hop delivery from source node to destination node via 0 or more intermediate nodes, with manual routing.
///
/// - RHMesh
/// Multi-hop delivery with automatic route discovery and rediscovery.
///
/// Any Manager may be used with any Driver.
///
/// \par Platforms
/// 
/// A range of platforms is supported:
///
/// - Arduino and the Arduino IDE (version 1.0 to 1.8.1 and later)
/// Including Diecimila, Uno, Mega, Leonardo, Yun, Due, Zero etc. http://arduino.cc/, Also similar boards such as 
///  - Moteino http://lowpowerlab.com/moteino/ 
///  - Anarduino Mini http://www.anarduino.com/mini/ 
///  - RedBearLab Blend V1.0 http://redbearlab.com/blend/ (with Arduino 1.0.5 and RedBearLab Blend Add-On version 20140701) 
///  -  MoteinoMEGA https://lowpowerlab.com/shop/moteinomega 
///     (with Arduino 1.0.5 and the MoteinoMEGA Arduino Core 
///     https://github.com/LowPowerLab/Moteino/tree/master/MEGA/Core)
///  - ESP8266 on Arduino IDE and Boards Manager per https://github.com/esp8266/Arduino 
///    Tested using Arduino 1.6.8 with esp8266 by ESP8266 Community version 2.1.0
///    Examples serial_reliable_datagram_* and ask_* are shown to work. 
///    CAUTION: The GHz radio included in the ESP8266 is
///    not yet supported.
///  - Various Talk2 Whisper boards eg https://wisen.com.au/store/products/whisper-node-lora.
///    Use Arduino Board Manager to install the Talk2 code support. 
///  - etc.
///
/// - ChipKIT Core with Arduino IDE on any ChipKIT Core supported Digilent processor (tested on Uno32)
/// http://chipkit.net/wiki/index.php?title=ChipKIT_core
///
/// - Maple and Flymaple boards with libmaple and the Maple-IDE development environment
/// http://leaflabs.com/devices/maple/ and http://www.open-drone.org/flymaple
///
/// - Teensy including Teensy 3.1 and earlier built using Arduino IDE 1.0.5 to 1.6.4 and later with 
///   teensyduino addon 1.18 to 1.23 and later.
///   http://www.pjrc.com/teensy
///
/// - Particle Photon https://store.particle.io/collections/photon and ARM3 based CPU with built-in 
///   Wi-Fi transceiver and extensive IoT software suport. RadioHead does not support the built-in transceiver
///   but can be used to control other SPI based radios, Serial ports etc.
///   See below for details on how to build RadioHead for Photon
///
/// - ATtiny built using Arduino IDE 1.0.5 with the arduino-tiny support from https://code.google.com/p/arduino-tiny/
///   and Digispark built with Arduino 1.6.5.
///   (Caution: these are very small processors and not all RadioHead features may be available, depending on memory requirements)
///
/// - nRF51 compatible Arm chips such as nRF51822 with Arduino 1.6.4 and later using the procedures
///   in http://redbearlab.com/getting-started-nrf51822/
///
/// - nRF52 compatible Arm chips such as as Adafruit BLE Feather board
/// https://www.adafruit.com/product/3406
///
/// - Adafruit Feather. These are excellent boards that are available with a variety of radios. We tested with the 
///   Feather 32u4 with RFM69HCW radio, with Arduino IDE 1.6.8 and the Adafruit AVR Boards board manager version 1.6.10. 
///   https://www.adafruit.com/products/3076
///
/// - ESP32 built using Arduino IDE 1.8.1 or later using the ESP32 toolchain installed per
///   https://diyprojects.io/programming-esp32-board-arduino-ide-macos-windows-linux-arm-raspberrypi-orangepi/
///   The internal 2.4GHz radio is not yet supported. Tested with RFM22 using SPI interfcace
///
/// - Raspberry Pi
///   Uses BCM2835 library for GPIO http://www.airspayce.com/mikem/bcm2835/
///   Currently works only with RH_NRF24 driver or other drivers that do not require interrupt support.
///   Contributed by Mike Poublon.
///
/// - Linux and OSX
///   Using the RHutil/HardwareSerial class, the RH_Serial driver and any manager will
///   build and run on Linux and OSX. These can be used to build programs that talk securely and reliably to
///   Arduino and other processors or to other Linux or OSX hosts on a reliable, error detected datagram
///   protocol over a serial line.
///
/// Other platforms are partially supported, such as Generic AVR 8 bit processors, MSP430. 
/// We welcome contributions that will expand the range of supported platforms. 
///
/// RadioHead is available (through the efforts of others) 
/// for PlatformIO. PlatformIO is a cross-platform code builder and the missing library manager.
/// http://platformio.org/#!/lib/show/124/RadioHead
///
/// \par History
///
/// RadioHead was created in April 2014, substantially based on code from some of our other earlier Radio libraries:
///
/// - RHMesh, RHRouter, RHReliableDatagram and RHDatagram are derived from the RF22 library version 1.39.
/// - RH_RF22 is derived from the RF22 library version 1.39.
/// - RH_RF69 is derived from the RF69 library version 1.2.
/// - RH_ASK is based on the VirtualWire library version 1.26, after significant conversion to C++.
/// - RH_Serial was new.
/// - RH_NRF24 is based on the NRF24 library version 1.12, with some significant changes.
///
/// During this combination and redevelopment, we have tried to retain all the processor dependencies and support from
/// the libraries that were contributed by other people. However not all platforms can be tested by us, so if you
/// find that support from some platform has not been successfully migrated, please feel free to fix it and send us a 
/// patch.
///
/// Users of RHMesh, RHRouter, RHReliableDatagram and RHDatagram in the previous RF22 library will find that their
/// existing code will run mostly without modification. See the RH_RF22 documentation for more details.
///
/// \par Installation
///
/// Install in the usual way: unzip the distribution zip file to the libraries
/// sub-folder of your sketchbook. 
/// The example sketches will be visible in in your Arduino, mpide, maple-ide or whatever.
/// http://arduino.cc/en/Guide/Libraries
///
/// \par Building for Particle Photon
///
/// The Photon is not supported by the Arduino IDE, so it takes a little effort to set up a build environment.
/// Heres what we did to enable building of RadioHead example sketches on Linux, 
/// but there are other ways to skin this cat.
/// Basic reference for getting stated is: http://particle-firmware.readthedocs.org/en/develop/build/
/// - Download the ARM gcc cross compiler binaries and unpack it in a suitable place:
/// \code
/// cd /tmp
/// wget https://launchpad.net/gcc-arm-embedded/5.0/5-2015-q4-major/+download/gcc-arm-none-eabi-5_2-2015q4-20151219-linux.tar.bz2
/// tar xvf gcc-arm-none-eabi-5_2-2015q4-20151219-linux.tar.bz2
/// \endcode
/// - If dfu-util and friends not installed on your platform, download dfu-util and friends to somewhere in your path
/// \code
/// cd ~/bin
/// wget http://dfu-util.sourceforge.net/releases/dfu-util-0.8-binaries/linux-i386/dfu-util
/// wget http://dfu-util.sourceforge.net/releases/dfu-util-0.8-binaries/linux-i386/dfu-suffix
/// wget http://dfu-util.sourceforge.net/releases/dfu-util-0.8-binaries/linux-i386/dfu-prefix
/// \endcode
/// - Download the Particle firmware (contains headers and libraries require to compile Photon sketches) 
///   to a suitable place:
/// \code
/// cd /tmp
/// wget https://github.com/spark/firmware/archive/develop.zip
/// unzip develop.zip
/// \endcode
/// - Make a working area containing the RadioHead library source code and your RadioHead sketch. You must
///   rename the sketch from .pde or .ino to application.cpp
/// \code
/// cd /tmp
/// mkdir RadioHead
/// cd RadioHead
/// cp /usr/local/projects/arduino/libraries/RadioHead/*.h .
/// cp /usr/local/projects/arduino/libraries/RadioHead/*.cpp .
/// cp /usr/local/projects/arduino/libraries/RadioHead/examples/cc110/cc110_client/cc110_client.pde application.cpp
/// \endcode
/// - Edit application.cpp and comment out any \#include <SPI.h> so it looks like:
/// \code
///   // #include <SPI.h>
/// \endcode
/// - Connect your Photon by USB. Put it in DFU mode as descibed in Photon documentation. Light should be flashing yellow
/// - Compile the RadioHead sketch and install it as the user program (this does not update the rest of the
///   Photon firmware, just the user part:
/// \code
/// cd /tmp/firmware-develop/main
/// PATH=$PATH:/tmp/gcc-arm-none-eabi-5_2-2015q4/bin make APPDIR=/tmp/RadioHead all PLATFORM=photon program-dfu
/// \endcode
/// - You should see RadioHead compile without errors and download the finished sketch into the Photon.
///
/// \par Compatible Hardware Suppliers
///
/// We have had good experiences with the following suppliers of RadioHead compatible hardware:
///
/// - LittleBird http://littlebirdelectronics.com.au in Australia for all manner of Arduinos and radios.
/// - LowPowerLab http://lowpowerlab.com/moteino in USA for the excellent Moteino and Moteino-USB 
///   boards which include Hope-RF RF69B radios on-board.
/// - Anarduino and HopeRF USA (http://www.hoperfusa.com and http://www.anarduino.com) who have a wide range
///   of HopeRF radios and Arduino integrated modules.
/// - SparkFun https://www.sparkfun.com/ in USA who design and sell a wide range of Arduinos and radio modules.
/// - Wisen http://wisen.com.au who design and sell a wide range of integrated radio/processor modules including the
///   excellent Talk2 range.
///
/// \par Coding Style
///
/// RadioHead is designed so it can run on small processors with very
/// limited resources and strict timing contraints.  As a result, we
/// tend only to use the simplest and least demanding (in terms of memory and CPU) C++
/// facilities. In particular we avoid as much as possible dynamic
/// memory allocation, and the use of complex objects like C++
/// strings, IO and buffers. We are happy with this, but we are aware
/// that some people may think we are leaving useful tools on the
/// table. You should not use this code as an example of how to do
/// generalised C++ programming on well resourced processors.
///
/// \par Donations
///
/// This library is offered under a free GPL license for those who want to use it that way. 
/// We try hard to keep it up to date, fix bugs
/// and to provide free support. If this library has helped you save time or money, please consider donating at
/// http://www.airspayce.com or here:
///
/// \htmlonly <form action="https://www.paypal.com/cgi-bin/webscr" method="post"><input type="hidden" name="cmd" value="_donations" /> <input type="hidden" name="business" value="mikem@airspayce.com" /> <input type="hidden" name="lc" value="AU" /> <input type="hidden" name="item_name" value="Airspayce" /> <input type="hidden" name="item_number" value="RadioHead" /> <input type="hidden" name="currency_code" value="USD" /> <input type="hidden" name="bn" value="PP-DonationsBF:btn_donateCC_LG.gif:NonHosted" /> <input type="image" alt="PayPal — The safer, easier way to pay online." name="submit" src="https://www.paypalobjects.com/en_AU/i/btn/btn_donateCC_LG.gif" /> <img alt="" src="https://www.paypalobjects.com/en_AU/i/scr/pixel.gif" width="1" height="1" border="0" /></form> \endhtmlonly
///
/// \subpage packingdata "Passing Sensor Data Between RadioHead nodes"
///
/// \par Trademarks
///
/// RadioHead is a trademark of AirSpayce Pty Ltd. The RadioHead mark was first used on April 12 2014 for
/// international trade, and is used only in relation to data communications hardware and software and related services.
/// It is not to be confused with any other similar marks covering other goods and services.
///
/// \par Copyright
///
/// This software is Copyright (C) 2011-2016 Mike McCauley. Use is subject to license
/// conditions. The main licensing options available are GPL V2 or Commercial:
/// 
/// \par Open Source Licensing GPL V2
///
/// This is the appropriate option if you want to share the source code of your
/// application with everyone you distribute it to, and you also want to give them
/// the right to share who uses it. If you wish to use this software under Open
/// Source Licensing, you must contribute all your source code to the open source
/// community in accordance with the GPL Version 2 when your application is
/// distributed. See https://www.gnu.org/licenses/gpl-2.0.html
/// 
/// \par Commercial Licensing
///
/// This is the appropriate option if you are creating proprietary applications
/// and you are not prepared to distribute and share the source code of your
/// application. Purchase commercial licenses at http://airspayce.binpress.com
///
/// \par Revision History
/// \version 1.1 2014-04-14<br>
///              Initial public release
/// \version 1.2 2014-04-23<br>
///              Fixed various typos. <br>
///              Added links to compatible Anarduino products.<br>
///              Added RHNRFSPIDriver, RH_NRF24 classes to support Nordic NRF24 based radios.
/// \version 1.3 2014-04-28<br>
///              Various documentation fixups.<br>
///              RHDatagram::setThisAddress() did not set the local copy of thisAddress. Reported by Steve Childress.<br>
///              Fixed a problem on Teensy with RF22 and RF69, where the interrupt pin needs to be set for input, <br>
///              else pin interrupt doesn't work properly. Reported by Steve Childress and patched by 
///              Adrien van den Bossche. Thanks.<br>
///              Fixed a problem that prevented RF22 honouring setPromiscuous(true). Reported by Steve Childress.<br>
///              Updated documentation to clarify some issues to do with maximum message lengths 
///              reported by Steve Childress.<br>
///              Added support for yield() on systems that support it (currently Arduino 1.5.5 and later)
///              so that spin-loops can suport multitasking. Suggested by Steve Childress.<br>
///              Added RH_RF22::setGpioReversed() so the reversal it can be configured at run-time after
///              radio initialisation. It must now be called _after_ init(). Suggested by Steve Childress.<br>
/// \version 1.4 2014-04-29<br>
///              Fixed further problems with Teensy compatibility for RH_RF22. Tested on Teensy 3.1.
///              The example/rf22_* examples now run out of the box with the wiring connections as documented for Teensy
///              in RH_RF22.<br>
///              Added YIELDs to spin-loops in RHRouter, RHMesh and RHReliableDatagram, RH_NRF24.<br>
///              Tested RH_Serial examples with Teensy 3.1: they now run out of the box.<br>
///              Tested RH_ASK examples with Teensy 3.1: they now run out of the box.<br>
///              Reduced default SPI speed for NRF24 from 8MHz to 1MHz on Teensy, to improve reliability when
///              poor wiring is in use.<br>
///              on some devices such as Teensy.<br>
///              Tested RH_NRF24 examples with Teensy 3.1: they now run out of the box.<br>
/// \version 1.5 2014-04-29<br>
///              Added support for Nordic Semiconductor nRF905 transceiver with RH_NRF905 driver. Also
///              added examples for nRF905 and tested on Teensy 3.1
/// \version 1.6 2014-04-30<br>
///              NRF905 examples were missing
/// \version 1.7 2014-05-03<br>
///              Added support for Arduino Due. Tested with RH_NRF905, RH_Serial, RH_ASK.
///              IMPORTANT CHANGE to interrupt pins on Arduino with RH_RF22 and RH_RF69 constructors:
///              previously, you had to specify the interrupt _number_ not the interrupt _pin_. Arduinos and Uno32
///              are now consistent with all other platforms: you must specify the interrupt pin number. Default
///              changed to pin 2 (a common choice with RF22 shields).
///              Removed examples/maple/maple_rf22_reliable_datagram_client and 
///              examples/maple/maple_rf22_reliable_datagram_client since the rf22 examples now work out
///              of the box with Flymaple.
///              Removed examples/uno32/uno32_rf22_reliable_datagram_client and 
///              examples/uno32/uno32_rf22_reliable_datagram_client since the rf22 examples now work out
///              of the box with ChipKit Uno32.
/// \version 1.8 2014-05-08 <br>
///              Added support for YIELD in Teensy 2 and 3, suggested by Steve Childress.<br>
///              Documentation updates. Clarify use of headers and Flags<br>
///              Fixed misalignment in RH_RF69 between ModemConfigChoice definitions and the implemented choices
///              which meant you didnt get the choice you thought and GFSK_Rb55555Fd50 hung the transmitter.<br>
///              Preliminary work on Linux simulator.
/// \version 1.9 2014-05-14 <br>
///              Added support for using Timer 2 instead of Timer 1 on Arduino in RH_ASK when
///              RH_ASK_ARDUINO_USE_TIMER2 is defined. With the kind assistance of
///              Luc Small. Thanks!<br>
///              Updated comments in RHReliableDatagram concerning servers, retries, timeouts and delays.
///              Fixed an error in RHReliableDatagram where recvfrom return value was not checked.
///              Reported by Steve Childress.<br>
///              Added Linux simulator support so simple RadioHead sketches can be compiled and run on Linux.<br>
///              Added RH_TCP driver to permit message passing between simulated sketches on Linux.<br>
///              Added example simulator sketches.<br>
///              Added tools/etherSimulator.pl, a simulator of the 'Luminiferous Ether' that passes
///              messages between simulated sketches and can simulate random message loss etc.<br>
///              Fixed a number of typos and improved some documentation.<br>
/// \version 1.10 2014-05-15 <br>
///              Added support for RFM73 modules to RH_NRF24. These 2 radios are very similar, and can interoperate
///              with each other. Added new RH_NRF24::TransmitPower enums for the RFM73, which has a different 
///              range of available powers<br>
///              reduced the default SPI bus speed for RH_NRF24 to 1MHz, since so many modules and CPU have problems
///              with 8MHz.<br>
/// \version 1.11 2014-05-18<br>
///              Testing RH_RF22 with RFM23BP and 3.3V Teensy 3.1 and 5V Arduinos. 
///              Updated documentation with respect to GPIO and antenna
///              control pins for RFM23. Updated documentation with respect to transmitter power control for RFM23<br>
///              Fixed a problem with RH_RF22 driver, where GPIO TX and RX pins were not configured during
///              initialisation, causing poor transmit power and sensitivity on those RF22/RF23 devices where GPIO controls
///              the antenna selection pins.
/// \version 1.12 2014-05-20<br>
///              Testing with RF69HW and the RH_RF69 driver. Works well with the Anarduino MiniWireless -CW and -HW 
///              boards http://www.anarduino.com/miniwireless/ including
///              the marvellous high powered MinWireless-HW (with 20dBm output for excellent range).<br>
///              Clarified documentation of RH_RF69::setTxPower values for different models of RF69.<br>
///              Added RHReliableDatagram::resetRetransmissions().<br>
///              Retransmission count precision increased to uin32_t.<br>
///              Added data about actual power measurements from RFM22 module.<br>
/// \version 1.13 2014-05-23<br>
///              setHeaderFlags(flags) changed to setHeaderFlags(set, clear), enabling any flags to be
///              individually set and cleared by either RadioHead or application code. Requested by Steve Childress.<br>
///              Fixed power output setting for boost power on RF69HW for 18, 19 and 20dBm.<br>
///              Added data about actual power measurements from RFM69W and RFM69HW modules.<br>
/// \version 1.14 2014-05-26<br>
///              RH_RF69::init() now always sets the PA boost back to the default settings, else can get invalid
///              PA power modes after uploading new sketches without a power cycle. Reported by Bryan.<br>
///              Added new macros RH_VERSION_MAJOR RH_VERSION_MINOR, with automatic maintenance in Makefile.<br>
///              Improvements to RH_TCP: constructor now honours the server argument in the form "servername:port".<br>
///              Added YIELD to RHReliableDatagram::recvfromAckTimeout. Requested by Steve Childress.<br>
///              Fixed a problem with RH_RF22 reliable datagram acknowledgements that was introduced in version 1.13.
///              Reported by Steve Childress.<br>
/// \version 1.15 2014-05-27<br>
///              Fixed a problem with the RadioHead .zip link.
/// \version 1.16 2014-05-30 <br>
///              Fixed RH_RF22 so that lastRssi() returns the signal strength in dBm. Suggested by Steve Childress.<br>
///              Added support for getLastPreambleTime() to RH_RF69. Requested by Steve Childress.<br>
///              RH_NRF24::init() now checks if there is a device connected and responding, else init() will fail.
///              Suggested by Steve Brown.<br>
///              RHSoftwareSPI now initialises default values for SPI pins MOSI = 12, MISO = 11 and SCK = 13.<br>
///              Fixed some problems that prevented RH_NRF24 working with mixed software and hardware SPI 
///              on different devices: a race condition
///              due to slow SPI transfers and fast acknowledgement.<br>
/// \version 1.17 2014-06-02 <br>
///              Fixed a debug typo in RHReliableDatagram that was introduced in 1.16.<br>
///              RH_NRF24 now sets default power, data rate and channel in init(), in case another
///              app has previously set different values without powerdown.<br>
///              Caution: there are still problems with RH_NRF24 and Software SPI. Do not use.<br>
/// \version 1.18 2014-06-02<br>
///              Improvements to performance of RH_NRF24 statusRead, allowing RH_NRF24 and Software SPI
///              to operate on slow devices like Arduino Uno.<br>
/// \version 1.19 2014-06-19<br>
///              Added examples ask_transmitter.pde and ask_receiver.pde.<br>
///              Fixed an error in the RH_RF22 doc for connection of Teensy to RF22.<br>
///              Improved documentation of start symbol bit patterns in RH_ASK.cpp
/// \version 1.20 2014-06-24<br>
///              Fixed a problem with compiling on platforms such as ATTiny where SS is not defined.<br>
///              Added YIELD to RHMesh::recvfromAckTimeout().<br>
/// \version 1.21 2014-06-24<br>
///              Fixed an issue in RH_Serial where characters might be lost with back-to-back frames.
///              Suggested by Steve Childress.<br>
///              Brought previous RHutil/crc16.h code into mainline RHCRC.cpp to prevent name collisions
///              with other similarly named code in other libraries. Suggested by Steve Childress.<br>
///              Fix SPI bus speed errors on 8MHz Arduinos.
/// \version 1.22 2014-07-01<br>
///              Update RH_ASK documentation for common wiring connections.<br>
///              Testing RH_ASK with HopeRF RFM83C/RFM85 courtesy Anarduino http://www.anarduino.com/<br>
///              Testing RH_NRF24 with Itead Studio IBoard Pro http://imall.iteadstudio.com/iboard-pro.html
///              using both hardware SPI on the ITDB02 Parallel LCD Module Interface pins and software SPI
///              on the nRF24L01+ Module Interface pins. Documented wiring required.<br>
///              Added support for AVR 1284 and 1284p, contributed by Peter Scargill.
///              Added support for Semtech SX1276/77/78 and HopeRF RFM95/96/97/98 and other similar LoRa capable radios
///              in LoRa mode only. Tested with the excellent MiniWirelessLoRa from 
///              Anarduino http://www.anarduino.com/miniwireless<br>
/// \version 1.23 2014-07-03<br>
///              Changed the default modulation for RH_RF69 to GFSK_Rb250Fd250, since the previous default
///              was not very reliable.<br>
///              Documented RH_RF95 range tests.<br>
///              Improvements to RH_RF22 RSSI readings so that lastRssi correctly returns the last message in dBm.<br>
/// \version 1.24 2014-07-18
///              Added support for building RadioHead for STM32F4 Discovery boards, using the native STM Firmware libraries,
///              in order to support Codec2WalkieTalkie (http://www.airspayce.com/mikem/Codec2WalkieTalkie)
///              and other projects. See STM32ArduinoCompat.<br>
///              Default modulation for RH_RF95 was incorrectly set to a very slow Bw125Cr48Sf4096
/// \version 1.25 2014-07-25
///              The available() function will longer terminate any current transmission, and force receive mode. 
///              Now, if there is no unprocessed incoming message and an outgoing message is currently being transmitted, 
///              available() will return false.<br>
///              RHRouter::sendtoWait(uint8_t*, uint8_t, uint8_t, uint8_t) renamed to sendtoFromSourceWait due to conflicts
///              with new sendtoWait() with optional flags.<br>
///              RHMEsh and RHRouter already supported end-to-end application layer flags, but RHMesh::sendtoWait() 
///              and RHRouter::sendToWait have now been extended to expose a way to send optional application layer flags.
/// \version 1.26 2014-08-12
///              Fixed a Teensy 2.0 compile problem due yield() not available on Teensy < 3.0. <br>
///              Adjusted the algorithm of RH_RF69::temperatureRead() to more closely reflect reality.<br>
///              Added functions to RHGenericDriver to get driver packet statistics: rxBad(), rxGood(), txGood().<br>
///              Added RH_RF69::printRegisters().<br>
///              RH_RF95::printRegisters() was incorrectly printing the register index instead of the address.
///              Reported by Phang Moh Lim.<br>
///              RH_RF95, added definitions for some more registers that are usable in LoRa mode.<br>
///              RH_RF95::setTxPower now uses RH_RF95_PA_DAC_ENABLE to achieve 21, 22 and 23dBm.<br>
///              RH_RF95, updated power output measurements.<br>
///              Testing RH_RF69 on Teensy 3.1 with RF69 on PJRC breakout board. OK.<br>
///              Improvements so RadioHead will build under Arduino where SPI is not supported, such as 
///              ATTiny.<br>
///              Improvements so RadioHead will build for ATTiny using Arduino IDE and tinycore arduino-tiny-0100-0018.zip.<br>
///              Testing RH_ASK on ATTiny85. Reduced RAM footprint. 
///              Added helpful documentation. Caution: RAM memory is *very* tight on this platform.<br>
///              RH_RF22 and RH_RF69, added setIdleMode() function to allow the idle mode radio operating state
///              to be controlled for lower idle power consumption at the expense of slower transitions to TX and RX.<br>
/// \version 1.27 2014-08-13
///              All RH_RF69 modulation schemes now have data whitening enabled by default.<br>
///              Tested and added a number of OOK modulation schemes to RH_RF69 Modem config table.<br>
///              Minor improvements to a number of the faster RH_RF69 modulation schemes, but some slower ones
///              are still not working correctly.<br>
/// \version 1.28 2014-08-20
///              Added new RH_RF24 driver to support Si446x, RF24/26/26, RFM24/26/27 family of transceivers.
///              Tested with the excellent
///              Anarduino Mini and RFM24W and RFM26W with the generous assistance of the good people at 
///              Anarduino http://www.anarduino.com.
/// \version 1.29 2014-08-21
///              Fixed a compile error in RH_RF24 introduced at the last minute in hte previous release.<br>
///              Improvements to RH_RF69 modulation schemes: now include the AFCBW in teh ModemConfig.<br>
///              ModemConfig RH_RF69::FSK_Rb2Fd5 and RH_RF69::GFSK_Rb2Fd5 are now working.<br> 
/// \version 1.30 2014-08-25
///              Fixed some compile problems with ATtiny84 on Arduino 1.5.5 reported by Glen Cook.<br>
/// \version 1.31 2014-08-27
///              Changed RH_RF69 FSK and GFSK modulations from Rb2_4Fd2_4 to Rb2_4Fd4_8 and FSK_Rb4_8Fd4_8 to FSK_Rb4_8Fd9_6
///              since the previous ones were unreliable (they had modulation indexes of 1).<br>
/// \version 1.32 2014-08-28
///              Testing with RedBearLab Blend board http://redbearlab.com/blend/. OK.<br>
///              Changed more RH_RF69 FSK and GFSK slowish modulations to have modulation index of 2 instead of 1. 
///              This required chnaging the symbolic names.<br>
/// \version 1.33 2014-09-01
///              Added support for sleep mode in RHGeneric driver, with new mode 
///              RHModeSleep and new virtual function sleep().<br>
///              Added support for sleep to RH_RF69, RH_RF22, RH_NRF24, RH_RF24, RH_RF95 drivers.<br>
/// \version 1.34 2014-09-19
///              Fixed compile errors in example rf22_router_test.<br>
///              Fixed a problem with RH_NRF24::setNetworkAddress, also improvements to RH_NRF24 register printing.
///              Patched by Yveaux.<br>
///              Improvements to RH_NRF24 initialisation for version 2.0 silicon.<br>
///              Fixed problem with ambigiguous print call in RH_RFM69 when compiling for Codec2.<br>
///              Fixed a problem with RH_NRF24 on RFM73 where the LNA gain was not set properly, reducing the sensitivity
///              of the receiver.
/// \version 1.35 2014-09-19
///              Fixed a problem with interrupt setup on RH_RF95 with Teensy3.1. Reported by AD.<br>
/// \version 1.36 2014-09-22
///              Improvements to interrupt pin assignments for __AVR_ATmega1284__ and__AVR_ATmega1284P__, provided by
///              Peter Scargill.<br>
///              Work around a bug in Arduino 1.0.6 where digitalPinToInterrupt is defined but NOT_AN_INTERRUPT is not.<br>
///  \version 1.37 2014-10-19
///              Updated doc for connecting RH_NRF24 to Arduino Mega.<br>
///              Changes to RHGenericDriver::setHeaderFlags(), so that the default for the clear argument
///              is now RH_FLAGS_APPLICATION_SPECIFIC, which is less surprising to users.
///              Testing with the excellent MoteinoMEGA from LowPowerLab 
///              https://lowpowerlab.com/shop/moteinomega with on-board RFM69W.
///  \version 1.38 2014-12-29
///              Fixed compile warning on some platforms where RH_RF24::send and RH_RF24::writeTxFifo 
///              did not return a value.<br>
///              Fixed some more compiler warnings in RH_RF24 on some platforms.<br>
///              Refactored printRegisters for some radios. Printing to Serial
///              is now controlled by the definition of RH_HAVE_SERIAL.<br>
///              Added partial support for ARM M4 w/CMSIS with STM's Hardware Abstraction lib for 
///              Steve Childress.<br>
///  \version 1.39 2014-12-30
///              Fix some compiler warnings under IAR.<br>
///              RH_HAVE_SERIAL and Serial.print calls removed for ATTiny platforms.<br>
///  \version 1.40 2015-03-09
///              Added notice about availability on PlatformIO, thanks to Ivan Kravets.<br>
///              Fixed a problem with RH_NRF24 where short packet lengths would occasionally not be trasmitted
///              due to a race condition with RH_NRF24_TX_DS. Reported by Mark Fox.<br>
///  \version 1.41 2015-03-29
///              RH_RF22, RH_RF24, RH_RF69 and RH_RF95 improved to allow driver.init() to be called multiple
///              times without reallocating a new interrupt, allowing the driver to be reinitialised
///              after sleeping or powering down.
///  \version 1.42 2015-05-17
///              Added support for RH_NRF24 driver on Raspberry Pi, using BCM2835
///              library for GPIO pin IO. Contributed by Mike Poublon.<br>
///              Tested RH_NRF24 module with NRF24L01+PA+LNA SMA Antenna Wireless Transceiver modules
///              similar to: http://www.elecfreaks.com/wiki/index.php?title=2.4G_Wireless_nRF24L01p_with_PA_and_LNA
///              works with no software changes. Measured max power output 18dBm.<br>
///  \version 1.43 2015-08-02
///              Added RH_NRF51 driver to support Nordic nRF51 family processor with 2.4GHz radio such 
///              as nRF51822, to be built on Arduino 1.6.4 and later. Tested with RedBearLabs nRF51822 board
///              and BLE Nano kit<br>
///  \version 1.44 2015-08-08
///              Fixed errors with compiling on some platforms without serial, such as ATTiny. 
///              Reported by Friedrich Müller.<br>
///  \version 1.45 2015-08-13
///              Added support for using RH_Serial on Linux and OSX (new class RHutil/HardwareSerial
///              encapsulates serial ports on those platforms). Example examples/serial upgraded
///              to build and run on Linux and OSX using the tools/simBuild builder.
///              RHMesh, RHRouter and RHReliableDatagram updated so they can use RH_Serial without
///              polling loops on Linux and OSX for CPU efficiency.<br>
///  \version 1.46 2015-08-14
///              Amplified some doc concerning Linux and OSX RH_Serial. Added support for 230400
///              baud rate in HardwareSerial.<br>
///              Added sample sketches nrf51_audio_tx and nrf51_audio_rx which show how to
///              build an audio TX/RX pair with RedBear nRF51822 boards and a SparkFun MCP4725 DAC board.
///              Uses the built-in ADC of the nRF51822 to sample audio at 5kHz and transmit packets
///              to the receiver which plays them via the DAC.<br>
/// \version 1.47 2015-09-18
///              Removed top level Makefile from distribution: its only used by the developer and 
///              its presence confuses some people.<br>
///              Fixed a problem with RHReliableDatagram with some versions of Raspberry Pi random() that causes 
///              problems: random(min, max) sometimes exceeds its max limit.
/// \version 1.48 2015-09-30
///              Added support for Arduino Zero. Tested on Arduino Zero Pro.
/// \version 1.49 2015-10-01
///              Fixed problems that prevented interrupts working correctly on Arduino Zero and Due.
///              Builds and runs with 1.6.5 (with 'Arduino SAMD Boards' for Zero version 1.6.1) from arduino.cc.
///              Arduino version 1.7.7 from arduino.org is not currently supported.
/// \version 1.50 2015-10-25
///              Verified correct building and operation with Arduino 1.7.7 from arduino.org.
///              Caution: You must burn the bootloader from 1.7.7 to the Arduino Zero before it will 
///              work with Arduino 1.7.7 from arduino.org. Conversely, you must burn the bootloader from 1.6.5 
///              to the Arduino Zero before it will 
///              work with Arduino 1.6.5 from arduino.cc. Sigh.
///              Fixed a problem with RH_NRF905 that prevented the power and frequency ranges being set
///              properly. Reported by Alan Webber.
/// \version 1.51 2015-12-11
///              Changes to RH_RF6::setTxPower() to be compatible with SX1276/77/78/79 modules that
///              use RFO transmitter pins instead of PA_BOOST, such as the excellent
///              Modtronix inAir4 http://modtronix.com/inair4.html 
///              and inAir9 modules http://modtronix.com/inair9.html. With the kind assistance of 
///              David from Modtronix.
/// \version 1.52 2015-12-17
///              Added RH_MRF89 module to suport Microchip MRF89XA and compatible transceivers.
///              and modules.<br>
/// \version 1.53 2016-01-02
///              Added RH_CC110 module to support Texas Instruments CC110L and compatible transceivers and modules.<br>
/// \version 1.54 2016-01-29
///              Added support for ESP8266 processor on Arduino IDE. Examples serial_reliable_datagram_* are shown to work. 
///              CAUTION: SPI not supported yet. Timers used by RH_ASK are not tested. 
///              The GHz radio included in the ESP8266 is not yet supported. 
/// \version 1.55 2016-02-12
///              Added macros for htons() and friends to RadioHead.h.
///              Added example sketch serial_gateway.pde. Acts as a transparent gateway between RH_RF22 and RH_Serial, 
///              and with minor mods acts as a universal gateway between any 2 RadioHead driver networks.
///              Initial work on supporting STM32 F2 on Particle Photon: new platform type defined.
///              Fixed many warnings exposed by test building for Photon.
///              Particle Photon tested support for RH_Serial, RH_ASK, SPI, RH_CC110 etc.
///              Added notes on how to build RadioHead sketches for Photon.
/// \version 1.56 2016-02-18 
///              Implemented timers for RH_ASK on ESP8266, added some doc on IO pin selection.
/// \version 1.57 2016-02-23
///              Fixed an issue reported by S3B, where RH_RF22 would sometimes not clear the rxbufvalid flag.
/// \version 1.58 2-16-04-04
///              Tested RH_RF69 with Arduino Due. OK. Updated doc.<br>
///              Added support for all ChipKIT Core supported boards 
///              http://chipkit.net/wiki/index.php?title=ChipKIT_core
///              Tested on ChipKIT Uno32.<br>
///              Digilent Uno32 under the old MPIDE is no longer formally 
///              supported but may continue to work for some time.<br>
/// \version 1.59 2016-04-12
///              Testing with the excellent Rocket Scream Mini Ultra Pro with the RFM95W and RFM69HCW modules from
///              http://www.rocketscream.com/blog/product/mini-ultra-pro-with-radio/  (915MHz versions). Updated
///              documentation with hints to suit. Caution: requires Arduino 1.6.8 and Arduino SAMD Boards 1.6.5.
///              See also http://www.rocketscream.com/blog/2016/03/10/radio-range-test-with-rfm69hcw/
///              for the vendors tests and range with the RFM69HCW version. They also have an RF95 version equipped with
///              TCXO temperature controllled oscillator for extra frequency stability and support of very slow and
///              long range protocols.
///              These boards are highly recommended. They also include battery charging support.
/// \version 1.60 2016-06-25
///              Tested with the excellent talk2 Whisper Node boards 
///             (https://talk2.wisen.com.au/ and https://bitbucket.org/talk2/), 
///              an Arduino Nano compatible board, which include an on-board RF69 radio, external antenna, 
///              run on 2xAA batteries and support low power operations. RF69 examples work without modification.
///              Added support for ESP8266 SPI, provided by David Skinner.
/// \version 1.61 2016-07-07
///              Patch to RH_ASK.cpp for ESP8266, to prevent crashes in interrupt handlers. Patch from Alexander Mamchits.
/// \version 1.62 2016-08-17
///              Fixed a problem in RH_ASK where _rxInverted was not properly initialised. Reported by "gno.sun.sop".
///              Added support for  waitCAD() and isChannelActive() and setCADTimeout() to RHGeneric.
///              Implementation of RH_RF95::isChannelActive() allows the RF95 module to support
///              Channel Activity Detection (CAD). Based on code contributed by Bent Guldbjerg Christensen.
///              Implmentations of isChannelActive() plus documentation for other radio modules wil be welcomed.
/// \version 1.63 2016-10-20
///              Testing with Adafruit Feather 32u4 with RFM69HCW. Updated documentation to reflect.<br>
/// \version 1.64 2016-12-10
///              RHReliableDatagram now initialises _seenids. Fix from Ben Lim.<br>
///              In RH_NRF51, added get_temperature().<br>
///              In RH_NRF51, added support for AES packet encryption, which required a slight change 
///              to the on-air message format.<br>
/// \version 1.65 2017-01-11
///              Fixed a race condition with RH_NRF51 that prevented ACKs being reliably received.<br>
///              Removed code in RH_NRF51 that enabled the DC-DC converter. This seems not to be a necessary condition
///              for the radio to work and is now left to the application if that is required.<br>
///              Proven interoperation between nRF51822 and nRF52832.<br>
///              Modification and testing of RH_NRF51 so it works with nRF52 family processors,
///              such Sparkfun nRF52832 breakout board, with Arduino 1.6.13 and
///              Sparkfun nRF52 boards manager 0.2.3 using the procedures outlined in
///              https://learn.sparkfun.com/tutorials/nrf52832-breakout-board-hookup-guide<br>
///              Caution, the Sparkfun development system for Arduino is still immature. We had to 
///              rebuild the nrfutil program since the supplied one was not suitable for 
///              the Linux host we were developing on. See https://forum.sparkfun.com/viewtopic.php?f=32&t=45071
///              Also, after downloading a sketch in the nRF52832, the program does not start executing cleanly: 
///              you have to reset the processor again by pressing the reset button. 
///              This appears to be a problem with nrfutil, rather than a bug in RadioHead.
/// \version 1.66 2017-01-15
///              Fixed some errors in (unused) register definitions in RH_RF95.h.<br>
///              Fixed a problem that caused compilation errors in RH_NRF51 if the appropriate board 
///              support was not installed.
/// \version 1.67 2017-01-24
///              Added RH_RF95::frequencyError() to return the estimated centre frequency offset in Hz 
///              of the last received message
/// \version 1.68 2017-01-25
///              Fixed arithmetic error in RH_RF95::frequencyError() for some platforms.
/// \version 1.69 2017-02-02
///              Added RH_RF95::lastSNR() and improved lastRssi() calculations per the manual.
/// \version 1.70 2017-02-03
///              Added link to Binpress commercial license purchasing.
/// \version 1.71 2017-02-07
///              Improved support for STM32. Patch from Bent Guldbjerg Christensen.
/// \version 1.72 2017-03-02
///              In RH_RF24, fixed a problem where some important properties were not set by the ModemConfig.
///              Added properties 2007, 2008, 2009. Also properties 200a was not being set in the chip.
///              Reported by Shannon Bailey and Alan Adamson.
///              Fixed corresponding convert.pl and added it to the distribution.
/// \version 1.73 2017-03-04
///              Significant changes to RH_RF24 and its API. It is no longer possible to change the modulation scheme
///              programatically: it proved impossible to cater for all the possible crystal frequencies,
///              base frequency and modulation schemes. Instead you can use one of a small set of supplied radio
///              configuration header files, or generate your own with Silicon Labs WDS application. Changing
///              modulation scheme required editing RH_RF24.cpp to specify the appropriate header and recompiling.
///              convert.pl is now redundant and removed from the distribution.
/// \version 1.74 2017-03-08
///              Changed RHReliableDatagram so it would not ACK messages heard addressed to other nodes
///              in promiscuous mode.<br>
///              Added RH_RF24::deviceType() to return the integer value of the connected device.<br>
///              Added documentation about how to connect RFM69 to an ESP8266. Tested OK.<br>
///              RH_RF24 was not correctly changing state in sleep() and setModeIdle().<br>
///              Added example rf24_lowpower_client.pde showing how to put an arduino and radio into a low power
///              mode between transmissions to save battery power.<br>
///              Improvements to RH_RF69::setTxPower so it now takes an optional ishighpowermodule
///              flag to indicate if the connected module is a high power RFM69HW, and so set the power level
///              correctly. Based on code contributed by bob.
/// \version 1.75 2017-06-22
///              Fixed broken compiler issues with RH_RF95::frequencyError() reported by Steve Rogerson.<br>
///              Testing with the very excellent Rocket Scream boards equipped with RF95 TCXO modules. The
///              temperature controlled oscillator stabilises the chip enough to be able to use even the slowest
///              protocol Bw125Cr48Sf4096. Caution, the TCXO model radios are not low power when in sleep (consuming
///              about ~600 uA, reported by Phang Moh Lim).<br>
///              Added support for EBYTE E32-TTL-1W and family serial radio transceivers. These RF95 LoRa based radios
///              can deliver reliable messages at up to 7km measured.
/// \version 1.76 2017-06-23
///              Fixed a problem with RH_RF95 hanging on transmit under some mysterious circumstances.
///              Reported by several people at  https://forum.pjrc.com/threads/41878-Probable-race-condition-in-Radiohead-library?p=146601#post146601 <br>
///              Increased the size of rssi variables to 16 bits to permit RSSI less than -128 as reported by RF95.
/// \version 1.77 2017-06-25
///              Fixed a compilation error with lastRssi().<br>
/// \version 1.78 2017-07-19
///              Fixed a number of unused variable warnings from g++.<br>
///              Added new module RHEncryptedDriver and examples, contributed by Philippe Rochat, which
///              adds encryption and decryption to any RadioHead transport driver, using any encryption cipher
///              supported by ArduinoLibs Cryptographic Library http://rweather.github.io/arduinolibs/crypto.html
///              Includes several examples.<br>
/// \version 1.79 2017-07-25
///              Added documentation about 'Passing Sensor Data Between RadioHead nodes'.<br>
///              Changes to RH_CC110 driver to calculate RSSI in dBm, based on a patch from Jurie Pieterse.<br>
///              Added missing passthroughmethoids to RHEncryptedDriver, allowing it to be used with RHDatagram,
///              RHReliableDatagram etc. Tested with RH_Serial. Added examples
/// \version 1.80 2017-10-04
///              Testing with the very fine Talk2 Whisper Node LoRa boards https://wisen.com.au/store/products/whisper-node-lora
///              an Arduino compatible board, which include an on-board RFM95/96 LoRa Radio (Semtech SX1276), external antenna, 
///              run on 2xAAA batteries and support low power operations. RF95 examples work without modification.
///              Use Arduino Board Manager to install the Talk2 code support. Upload the code with an FTDI adapter set to 5V.<br>
///              Added support for SPI transactions in development environments that support it with SPI_HAS_TRANSACTION.
///              Tested on ESP32 with RFM-22 and Teensy 3.1 with RF69
///              Added support for ESP32, tested with RFM-22 connected by SPI.<br>
/// 
///\version 1.81 2017-11-15
///              RH_CC110, moved setPaTable() from protected to public.<br>
///              RH_RF95 modem config Bw125Cr48Sf4096 altered to enable slow daat rate in register 26
///              as suggested by Dieter Kneffel.
///              Added support for nRF52 compatible Arm chips such as as Adafruit BLE Feather board
///              https://www.adafruit.com/product/3406, with a patch from Mike Bell.<br>
///              Fixed a problem where rev 1.80 broke Adafruit M0 LoRa support by declaring 
///              bitOrder variable always as a unsigned char. Reported by Guilherme Jardim.<br>
///              In RH_RF95, all modes now have AGC enabled, as suggested by Dieter Kneffel.<br>
///
/// \author  Mike McCauley. DO NOT CONTACT THE AUTHOR DIRECTLY. USE THE GOOGLE LIST GIVEN ABOVE

/*! \page packingdata 
\par Passing Sensor Data Between RadioHead nodes

People often ask about how to send data (such as numbers, sensor
readings etc) from one RadioHead node to another. Although this issue
is not specific to RadioHead, and more properly lies in the area of
programming for networks, we will try to give some guidance here.

One reason for the uncertainty and confusion in this area, especially
amongst beginners, is that there is no *best* way to do it. The best
solution for your project may depend on the range of processors and
data that you have to deal with. Also, it gets more difficult if you
need to send several numbers in one packet, and/or deal with floating
point numbers.

The principal cause of difficulty is that different microprocessors of
the kind that run RadioHead may have different ways of representing
binary data such as integers. Some processors are little-endian and
some are big-endian in the way they represent multi-byte integers
(https://en.wikipedia.org/wiki/Endianness). And different processors
and maths libraries may represent floating point numbers in radically
different ways:
(https://en.wikipedia.org/wiki/Floating-point_arithmetic)

All the RadioHead examples show how to send and receive simple ASCII
strings, and if thats all you want, refer to the examples folder in
your RadioHead distribution.  But your needs may be more complicated
than that.

The essence of all engineering is compromise so it will be up to you to
decide whats best for your paricular needs. The main choices are:
- Raw Binary
- Network Order Binary
- ASCII

\par Raw Binary

With this technique you just pack the raw binary numbers into the packet:

\code
// Sending a single integer
// in the transmitter:
...
uint16_t data = getsomevalue();
if (!driver.send((uint8_t*)&data, sizeof(data)))
{
    ...
\endcode

\code
// and in the receiver:
...
uint16_t data;
uint8_t datalen = sizeof(data);
if (   driver.recv((uint8_t*)&data, &datalen)
    && datalen == sizeof(data))
{
    // Have the data, so do something with it
    uint16_t xyz = data;
    ...
\endcode

If you need to send more than one number at a time, its best to pack
them into a structure

\code
// Sending several integers in a structure
// in a common header for your project:
typedef struct
{
    uint16_t   dataitem1;
    uint16_t   dataitem2;
} MyDataStruct;
...
\endcode

\code
// In the transmitter
...
MyDataStruct data;
data.dataitem1 = getsomevalue();
data.dataitem2 = getsomeothervalue();
if (!driver.send((uint8_t*)&data, sizeof(data)))
{
    ...
\endcode

\code
// in the receiver
MyDataStruct data;
uint8_t datalen = sizeof(data);
if (   driver.recv((uint8_t*)&data, &datalen)
    && datalen == sizeof(data))
{
    // Have the data, so do something with it
    uint16_t pqr = data.dataitem1;
    uint16_t xyz = data.dataitem2;
    ....
\endcode


The disadvantage with this simple technique becomes apparent if your
transmitter and receiver have different endianness: the integers you
receive will not be the same as the ones you sent (actually they are,
but with the internal bytes swapped around, so they probably wont make
sense to you). Endianness is not a problem if *every* data item you
send is a just single byte (uint8_t or int8_t or char).

So you should only adopt this technique if:
- You only send data items of a single byte each, or
- You are absolutely sure (now and forever into the future) that you
will only ever use the same processor in the transmitter and receiver.

\par Network Order Binary

One solution to the issue of endianness in your processors to to
always convert your data from the processor's native byte order to
'network byte order' before transmission and then convert it back to
the receiver's native byte order. You do this with the htons (host to
network short) macro and friends. These functions may be a no-op on
big-endian processors.

With this technique you convert every multi-byte number to and from
network byte order (note that in most Arduino processors an integer is
in fact a short, and is the same as int16_t. We prefer to use types
that explicitly specify their size so we can be sure of applying the
right conversions):

\code
// Sending a single integer
// in the transmitter:
...
uint16_t data = htons(getsomevalue());
if (!driver.send((uint8_t*)&data, sizeof(data)))
{
    ...
\endcode
\code
// and in the receiver:
...
uint16_t data;
uint8_t datalen = sizeof(data);
if (   driver.recv((uint8_t*)&data, &datalen)
    && datalen == sizeof(data))
{
    // Have the data, so do something with it
    uint16_t xyz = ntohs(data);
    ...
\endcode

If you need to send more than one number at a time, its best to pack
them into a structure

\code
// Sending several integers in a structure
// in a common header for your project:
typedef struct
{
    uint16_t   dataitem1;
    uint16_t   dataitem2;
} MyDataStruct;
...
\endcode
\code
// In the transmitter
...
MyDataStruct data;
data.dataitem1 = htons(getsomevalue());
data.dataitem2 = htons(getsomeothervalue());
if (!driver.send((uint8_t*)&data, sizeof(data)))
{
    ...
\endcode
\code
// in the receiver
MyDataStruct data;
uint8_t datalen = sizeof(data);
if (   driver.recv((uint8_t*)&data, &datalen)
    && datalen == sizeof(data))
{
    // Have the data, so do something with it
    uint16_t pqr = ntohs(data.dataitem1);
    uint16_t xyz = ntohs(data.dataitem2);
    ....
\endcode

This technique is quite general for integers but may not work if you
want to send floating point number between transmitters and receivers
that have different floating point number representations.


\par ASCII

In this technique, you transmit the printable ASCII equivalent of
each floating point and then convert it back to a float in the receiver:

\code
// In the transmitter
...
float data = getsomevalue();
uint8_t buf[15]; // Bigger than the biggest possible ASCII
snprintf(buf, sizeof(buf), "%f", data);
if (!driver.send(buf, strlen(buf) + 1)) // Include the trailing NUL
{
    ...
\endcode
\code

// In the receiver
...
float data;
uint8_t buf[15]; // Bigger than the biggest possible ASCII
uint8_t buflen = sizeof(buf);
if (driver.recv(buf, &buflen))
{
    // Have the data, so do something with it
    float data = atof(buf); // String to float
    ...
\endcode

\par Conclusion:

- This is just a basic introduction to the issues. You may need to
extend your study into related C/C++ programming techniques.

- You can extend these ideas to signed 16 bit (int16_t) and 32 bit
(uint32_t, int32_t) numbers.

- Things can be simple or complicated depending on the needs of your
project.

- We are not going to write your code for you: its up to you to take
these examples and explanations and extend them to suit your needs.

*/



#ifndef RadioHead_h
#define RadioHead_h

// Official version numbers are maintained automatically by Makefile:
#define RH_VERSION_MAJOR 1
#define RH_VERSION_MINOR 81

// Symbolic names for currently supported platform types
#define RH_PLATFORM_ARDUINO          1
#define RH_PLATFORM_MSP430           2
#define RH_PLATFORM_STM32            3
#define RH_PLATFORM_GENERIC_AVR8     4
#define RH_PLATFORM_UNO32            5
#define RH_PLATFORM_UNIX             6
#define RH_PLATFORM_STM32STD         7
#define RH_PLATFORM_STM32F4_HAL      8 
#define RH_PLATFORM_RASPI            9
#define RH_PLATFORM_NRF51            10
#define RH_PLATFORM_ESP8266          11
#define RH_PLATFORM_STM32F2          12
#define RH_PLATFORM_CHIPKIT_CORE     13
#define RH_PLATFORM_ESP32            14						   
#define RH_PLATFORM_NRF52            15

////////////////////////////////////////////////////
// Select platform automatically, if possible
#ifndef RH_PLATFORM
 #if (MPIDE>=150 && defined(ARDUINO))
  // Using ChipKIT Core on Arduino IDE
  #define RH_PLATFORM RH_PLATFORM_CHIPKIT_CORE
 #elif defined(MPIDE)
  // Uno32 under old MPIDE, which has been discontinued:
  #define RH_PLATFORM RH_PLATFORM_UNO32
#elif defined(NRF51)
  #define RH_PLATFORM RH_PLATFORM_NRF51
#elif defined(NRF52)
  #define RH_PLATFORM RH_PLATFORM_NRF52
 #elif defined(ESP8266)
  #define RH_PLATFORM RH_PLATFORM_ESP8266
 #elif defined(ESP32)
  #define RH_PLATFORM RH_PLATFORM_ESP32
 #elif defined(ARDUINO)
  #define RH_PLATFORM RH_PLATFORM_ARDUINO
 #elif defined(__MSP430G2452__) || defined(__MSP430G2553__)
  #define RH_PLATFORM RH_PLATFORM_MSP430
 #elif defined(MCU_STM32F103RE)
  #define RH_PLATFORM RH_PLATFORM_STM32
 #elif defined(STM32F2XX)
  #define RH_PLATFORM RH_PLATFORM_STM32F2
 #elif defined(USE_STDPERIPH_DRIVER)
  #define RH_PLATFORM RH_PLATFORM_STM32STD
 #elif defined(RASPBERRY_PI)
  #define RH_PLATFORM RH_PLATFORM_RASPI
#elif defined(__unix__) // Linux
  #define RH_PLATFORM RH_PLATFORM_UNIX
#elif defined(__APPLE__) // OSX
  #define RH_PLATFORM RH_PLATFORM_UNIX
 #else
  #error Platform not defined! 	
 #endif
#endif

#if defined(__AVR_ATtiny84__) || defined(__AVR_ATtiny85__) || defined(__AVR_ATtiny24__) || defined(__AVR_ATtiny44__) || defined(__AVR_ATtiny45__) || defined(__AVR_ATtinyX4__) || defined(__AVR_ATtinyX5__) || defined(__AVR_ATtiny2313__) || defined(__AVR_ATtiny4313__) || defined(__AVR_ATtinyX313__)
 #define RH_PLATFORM_ATTINY
#endif

////////////////////////////////////////////////////
// Platform specific headers:
#if (RH_PLATFORM == RH_PLATFORM_ARDUINO)
 #if (ARDUINO >= 100)
  #include <Arduino.h>
 #else
  #include <wiring.h>
 #endif
 #ifdef RH_PLATFORM_ATTINY
  #warning Arduino TinyCore does not support hardware SPI. Use software SPI instead.
 #else
  #include <SPI.h>
  #define RH_HAVE_HARDWARE_SPI
  #define RH_HAVE_SERIAL
 #endif

#elif (RH_PLATFORM == RH_PLATFORM_ESP8266) // ESP8266 processor on Arduino IDE
 #include <Arduino.h>
 #include <SPI.h>
 #define RH_HAVE_HARDWARE_SPI
 #define RH_HAVE_SERIAL

#elif (RH_PLATFORM == RH_PLATFORM_ESP32)   // ESP32 processor on Arduino IDE
 #include <Arduino.h>
 #include <SPI.h>
 #define RH_HAVE_HARDWARE_SPI
 #define RH_HAVE_SERIAL

#elif (RH_PLATFORM == RH_PLATFORM_MSP430) // LaunchPad specific
 #include "legacymsp430.h"
 #include "Energia.h"
 #include <SPI.h>
 #define RH_HAVE_HARDWARE_SPI
 #define RH_HAVE_SERIAL

#elif (RH_PLATFORM == RH_PLATFORM_UNO32 || RH_PLATFORM == RH_PLATFORM_CHIPKIT_CORE)
 #include <WProgram.h>
 #include <string.h>
 #include <SPI.h>
 #define RH_HAVE_HARDWARE_SPI
 #define memcpy_P memcpy
 #define RH_HAVE_SERIAL

#elif (RH_PLATFORM == RH_PLATFORM_STM32) // Maple, Flymaple etc
 #include <STM32ArduinoCompat/wirish.h>	
 #include <stdint.h>
 #include <string.h>
 #include <STM32ArduinoCompat/HardwareSPI.h>
 #define RH_HAVE_HARDWARE_SPI
 // Defines which timer to use on Maple
 #define MAPLE_TIMER 1
 #define PROGMEM
 #define memcpy_P memcpy
 #define Serial SerialUSB
 #define RH_HAVE_SERIAL

#elif (RH_PLATFORM == RH_PLATFORM_STM32F2) // Particle Photon with firmware-develop
 #include <stm32f2xx.h>
 #include <application.h>
 #include <math.h> // floor
 #define RH_HAVE_SERIAL
 #define RH_HAVE_HARDWARE_SPI

#elif (RH_PLATFORM == RH_PLATFORM_STM32STD) // STM32 with STM32F4xx_StdPeriph_Driver 
 #include <stm32f4xx.h>
 #include <wirish.h>	
 #include <stdint.h>
 #include <string.h>
 #include <math.h>
 #include <HardwareSPI.h>
 #define RH_HAVE_HARDWARE_SPI
 #define Serial SerialUSB
 #define RH_HAVE_SERIAL

#elif (RH_PLATFORM == RH_PLATFORM_GENERIC_AVR8) 
 #include <avr/io.h>
 #include <avr/interrupt.h>
 #include <util/delay.h>
 #include <string.h>
 #include <stdbool.h>
 #define RH_HAVE_HARDWARE_SPI
 #include <SPI.h>

// For Steve Childress port to ARM M4 w/CMSIS with STM's Hardware Abstraction lib. 
// See ArduinoWorkarounds.h (not supplied)
#elif (RH_PLATFORM == RH_PLATFORM_STM32F4_HAL) 
 #include <ArduinoWorkarounds.h>
 #include <stm32f4xx.h> // Also using ST's CubeMX to generate I/O and CPU setup source code for IAR/EWARM, not GCC ARM.
 #include <stdint.h>
 #include <string.h>
 #include <math.h>
 #define RH_HAVE_HARDWARE_SPI // using HAL (Hardware Abstraction Libraries from ST along with CMSIS, not arduino libs or pins concept.

#elif (RH_PLATFORM == RH_PLATFORM_RASPI)
 #define RH_HAVE_HARDWARE_SPI
 #define RH_HAVE_SERIAL
 #define PROGMEM
 #include <RHutil/RasPi.h>
 #include <string.h>
 //Define SS for CS0 or pin 24
 #define SS 8

#elif (RH_PLATFORM == RH_PLATFORM_NRF51)
 #define RH_HAVE_SERIAL
 #define PROGMEM
  #include <Arduino.h>

#elif (RH_PLATFORM == RH_PLATFORM_NRF52)
 #include <SPI.h>
 #define RH_HAVE_HARDWARE_SPI
 #define RH_HAVE_SERIAL
 #define PROGMEM
  #include <Arduino.h>

#elif (RH_PLATFORM == RH_PLATFORM_UNIX) 
 // Simulate the sketch on Linux and OSX
 #include <RHutil/simulator.h>
 #define RH_HAVE_SERIAL
#include <netinet/in.h> // For htons and friends

#else
 #error Platform unknown!
#endif

////////////////////////////////////////////////////
// This is an attempt to make a portable atomic block
#if (RH_PLATFORM == RH_PLATFORM_ARDUINO)
#if defined(__arm__)
  #include <RHutil/atomic.h>
 #else
  #include <util/atomic.h>
 #endif
 #define ATOMIC_BLOCK_START     ATOMIC_BLOCK(ATOMIC_RESTORESTATE) {
 #define ATOMIC_BLOCK_END }
#elif (RH_PLATFORM == RH_PLATFORM_CHIPKIT_CORE)
 // UsingChipKIT Core on Arduino IDE
 #define ATOMIC_BLOCK_START unsigned int __status = disableInterrupts(); {
 #define ATOMIC_BLOCK_END } restoreInterrupts(__status);
#elif (RH_PLATFORM == RH_PLATFORM_UNO32)
 // Under old MPIDE, which has been discontinued:
 #include <peripheral/int.h>
 #define ATOMIC_BLOCK_START unsigned int __status = INTDisableInterrupts(); {
 #define ATOMIC_BLOCK_END } INTRestoreInterrupts(__status);
#elif (RH_PLATFORM == RH_PLATFORM_STM32F2) // Particle Photon with firmware-develop
 #define ATOMIC_BLOCK_START { int __prev = HAL_disable_irq();
 #define ATOMIC_BLOCK_END  HAL_enable_irq(__prev); }
#elif (RH_PLATFORM == RH_PLATFORM_ESP8266)
// See hardware/esp8266/2.0.0/cores/esp8266/Arduino.h
 #define ATOMIC_BLOCK_START { uint32_t __savedPS = xt_rsil(15);
 #define ATOMIC_BLOCK_END xt_wsr_ps(__savedPS);}
#else 
 // TO BE DONE:
 #define ATOMIC_BLOCK_START
 #define ATOMIC_BLOCK_END
#endif

////////////////////////////////////////////////////
// Try to be compatible with systems that support yield() and multitasking
// instead of spin-loops
// Recent Arduino IDE or Teensy 3 has yield()
#if (RH_PLATFORM == RH_PLATFORM_ARDUINO && ARDUINO >= 155 && !defined(RH_PLATFORM_ATTINY)) || (TEENSYDUINO && defined(__MK20DX128__))
 #define YIELD yield();
#elif (RH_PLATFORM == RH_PLATFORM_ESP8266)
// ESP8266 also hash it
 #define YIELD yield();
#else
 #define YIELD
#endif

////////////////////////////////////////////////////
// digitalPinToInterrupt is not available prior to Arduino 1.5.6 and 1.0.6
// See http://arduino.cc/en/Reference/attachInterrupt
#ifndef NOT_AN_INTERRUPT
 #define NOT_AN_INTERRUPT -1
#endif
#ifndef digitalPinToInterrupt
 #if (RH_PLATFORM == RH_PLATFORM_ARDUINO) && !defined(__arm__)

  #if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__)
   // Arduino Mega, Mega ADK, Mega Pro
   // 2->0, 3->1, 21->2, 20->3, 19->4, 18->5
   #define digitalPinToInterrupt(p) ((p) == 2 ? 0 : ((p) == 3 ? 1 : ((p) >= 18 && (p) <= 21 ? 23 - (p) : NOT_AN_INTERRUPT)))

  #elif defined(__AVR_ATmega1284__) || defined(__AVR_ATmega1284P__) 
   // Arduino 1284 and 1284P - See Manicbug and Optiboot
   // 10->0, 11->1, 2->2
   #define digitalPinToInterrupt(p) ((p) == 10 ? 0 : ((p) == 11 ? 1 : ((p) == 2 ? 2 : NOT_AN_INTERRUPT)))

  #elif defined(__AVR_ATmega32U4__)
   // Leonardo, Yun, Micro, Pro Micro, Flora, Esplora
   // 3->0, 2->1, 0->2, 1->3, 7->4
   #define digitalPinToInterrupt(p) ((p) == 0 ? 2 : ((p) == 1 ? 3 : ((p) == 2 ? 1 : ((p) == 3 ? 0 : ((p) == 7 ? 4 : NOT_AN_INTERRUPT)))))

  #else
   // All other arduino except Due:
   // Serial Arduino, Extreme, NG, BT, Uno, Diecimila, Duemilanove, Nano, Menta, Pro, Mini 04, Fio, LilyPad, Ethernet etc
   // 2->0, 3->1
   #define digitalPinToInterrupt(p)  ((p) == 2 ? 0 : ((p) == 3 ? 1 : NOT_AN_INTERRUPT))

  #endif
  
 #elif (RH_PLATFORM == RH_PLATFORM_UNO32) || (RH_PLATFORM == RH_PLATFORM_CHIPKIT_CORE)
  // Hmmm, this is correct for Uno32, but what about other boards on ChipKIT Core?
  #define digitalPinToInterrupt(p) ((p) == 38 ? 0 : ((p) == 2 ? 1 : ((p) == 7 ? 2 : ((p) == 8 ? 3 : ((p) == 735 ? 4 : NOT_AN_INTERRUPT)))))

 #else
  // Everything else (including Due and Teensy) interrupt number the same as the interrupt pin number
  #define digitalPinToInterrupt(p) (p)
 #endif
#endif

// On some platforms, attachInterrupt() takes a pin number, not an interrupt number
#if (RH_PLATFORM == RH_PLATFORM_ARDUINO) && defined (__arm__) && (defined(ARDUINO_ARCH_SAMD) || defined(ARDUINO_SAM_DUE))
 #define RH_ATTACHINTERRUPT_TAKES_PIN_NUMBER
#endif

// Slave select pin, some platforms such as ATTiny do not define it.
#ifndef SS
 #define SS 10
#endif

// These defs cause trouble on some versions of Arduino
#undef abs
#undef round
#undef double

// Sigh: there is no widespread adoption of htons and friends in the base code, only in some WiFi headers etc
// that have a lot of excess baggage
#if RH_PLATFORM != RH_PLATFORM_UNIX && !defined(htons)
// #ifndef htons
// These predefined macros available on modern GCC compilers
 #if   __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
  // Atmel processors
  #define htons(x) ( ((x)<<8) | (((x)>>8)&0xFF) )
  #define ntohs(x) htons(x)
  #define htonl(x) ( ((x)<<24 & 0xFF000000UL) | \
                   ((x)<< 8 & 0x00FF0000UL) | \
                   ((x)>> 8 & 0x0000FF00UL) | \
                   ((x)>>24 & 0x000000FFUL) )
  #define ntohl(x) htonl(x)

 #elif __BYTE_ORDER__ == __ORDER_BIG_ENDIAN__
  // Others
  #define htons(x) (x)
  #define ntohs(x) (x)
  #define htonl(x) (x)
  #define ntohl(x) (x)

 #else
  #error "Dont know how to define htons and friends for this processor" 
 #endif
#endif

// This is the address that indicates a broadcast
#define RH_BROADCAST_ADDRESS 0xff

// Uncomment this is to enable Encryption (see RHEncryptedDriver):
// But ensure you have installed the Crypto directory from arduinolibs first:
// http://rweather.github.io/arduinolibs/index.html
//#define RH_ENABLE_ENCRYPTION_MODULE

#endif
