Support for Adafruit Pixie (#749)

* Support for Adafruit Pixie

* Updated based on PR review to align with library style and added Pixie constructor to NeoPixelBugLg

src/internal/NeoMethods.h

@@ -37,6 +37,10 @@ License along with NeoPixel.  If not, see
 #include "methods/Sm16716GenericMethod.h"
 #include "methods/Mbi6033GenericMethod.h"
 
+//Adafruit Pixie via UART, not platform specific
+//
+#include "methods/PixieStreamMethod.h"
+
 // Platform specific and One Wire (data) methods
 //
 #if defined(ARDUINO_ARCH_ESP8266)

src/internal/methods/PixieStreamMethod.h

@@ -0,0 +1,105 @@
+/*-------------------------------------------------------------------------
+NeoPixel library helper functions for DotStars using general Pins (APA102).
+
+Written by Michael C. Miller.
+
+I invest time and resources providing this open source code,
+please support me by dontating (see https://github.com/Makuna/NeoPixelBus)
+
+-------------------------------------------------------------------------
+This file is part of the Makuna/NeoPixelBus library.
+
+NeoPixelBus is free software: you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as
+published by the Free Software Foundation, either version 3 of
+the License, or (at your option) any later version.
+
+NeoPixelBus is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public
+License along with NeoPixel.  If not, see
+<http://www.gnu.org/licenses/>.
+-------------------------------------------------------------------------*/
+
+/*
+  Pixie reads data in at 115.2k serial, 8N1.
+  Byte order is R1, G1, B1, R2, G2, B2, ... where the first triplet is the
+  color of the LED that's closest to the controller. 1ms of silence triggers
+  latch. 2 seconds silence (or overheating) triggers LED off (for safety).
+*/
+
+
+#pragma once
+
+
+class PixieStreamMethod
+{
+public:
+    typedef NeoNoSettings SettingsObject;
+
+    PixieStreamMethod(uint16_t pixelCount, size_t elementSize, size_t settingsSize, Stream* pixieStream) :
+        _sizeData(pixelCount * elementSize + settingsSize),
+        _usEndTime(0),
+        _stream(pixieStream)
+    {
+        _data = static_cast<uint8_t*>(malloc(_sizeData));
+        // data cleared later in Begin()
+    }
+
+    ~PixieStreamMethod()
+    {
+        free(_data);
+    }
+
+    bool IsReadyToUpdate() const
+    {
+        return (micros() - _usEndTime) > 1000L; // ensure 1ms delay between calls
+    }
+
+    void Initialize()
+    {
+        // nothing to initialize, UART is managed outside this library
+    }
+
+    void Update(bool)
+    {
+        while (!IsReadyToUpdate())
+        {
+        }
+        _stream->write(_data, _sizeData);
+        _usEndTime = micros(); // Save time to ensure 1ms delay
+    }
+
+    bool AlwaysUpdate()
+    {
+        // Pixie expects to receive data every <2 seconds, Adafruit recommends <1.  
+        // Ensuring data is sent every <2 seconds needs to happen outside of the library
+        // Returning true will allow data to be re-sent even if no changes to buffer.
+
+        return true;
+    }
+
+    uint8_t* getData() const
+    {
+        return _data;
+    };
+
+    size_t getDataSize() const
+    {
+        return _sizeData;
+    };
+
+    void applySettings([[maybe_unused]] const SettingsObject& settings)
+    {
+    }
+
+private:
+    const size_t   _sizeData;   // Size of '_data' buffer below
+
+    uint8_t* _data;       // Holds LED color values
+    Stream* _stream;
+    uint32_t _usEndTime;  // microseconds EndTime
+};