Heltec SSD1306 Display Support (#1283)

My environment

[env:heltec-display]   ; Heltec ESP32 Board with SSD1306 display
platform = ${com.esp32_platform}
board = heltec_wifi_lora_32_V2
build_type = debug
monitor_filters = esp32_exception_decoder
board_build.partitions = min_spiffs.csv
extra_scripts = pre:scripts/omg_firmware_version.py
lib_deps =
  ${com-esp.lib_deps}
  ${libraries.wifimanager32}
  ${libraries.heltec}
;  ${libraries.m5stickcp}

build_flags =
  ${com-esp.build_flags}
  ${test_env.build_flags}
; *** OpenMQTTGateway Config ***
  '-UZmqttDiscovery'          ; disables MQTT Discovery
  '-DvalueAsATopic=true'
  '-DLOG_LEVEL=LOG_LEVEL_TRACE'
; *** OpenMQTTGateway Modules ***
  '-DZboardHELTEC="HELTEC"'
; *** Heltec Board Options ***
  '-DDEBUG_OLEDDISPLAY(...)=Serial.printf( __VA_ARGS__ )'
  '-DLOG_TO_LCD=true'         ; Enable log to LCD
  '-DLED_ERROR=2'
  '-DONBOARD_LED=25'          ; Onboard LED is GPIO 25 on the Heltec Board

monitor_port = /dev/cu.SLAB_USBtoUART
monitor_speed = 921600
upload_port = /dev/cu.SLAB_USBtoUART
upload_speed = 921600

1 - Set default LCD log level to WARNING
2 - Implemented a macro based displayPrint function that will be usable across different displays

- Added logo display when idle
- Fixed log-lcd mqtt function
- Enable OLED Display on Heltec Boards

main/config_HELTEC.h

@@ -0,0 +1,116 @@
+/*  
+  OpenMQTTGateway Addon  - ESP8266 or Arduino program for home automation 
+
+   Act as a wifi or ethernet gateway between your 433mhz/infrared IR signal  and a MQTT broker 
+   Send and receiving command by MQTT
+ 
+    HELTEC ESP32 LORA - SSD1306 / Onboard 0.96-inch 128*64 dot matrix OLED display
+  
+    Copyright: (c)Florian ROBERT
+    
+    Contributors:
+    - 1technophile
+    - NorthernMan54
+  
+    This file is part of OpenMQTTGateway.
+    
+    OpenMQTTGateway is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenMQTTGateway 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 General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef config_HELTEC_h
+#define config_HELTEC_h
+
+#include <Arduino.h>
+#include <Wire.h>
+
+#include "SSD1306Wire.h"
+
+#ifdef ZboardHELTEC
+#  define OLED_WIDTH       128
+#  define OLED_HEIGHT      64
+#  define OLED_TEXT_BUFFER 1000
+#  define OLED_TEXT_ROWS   5
+#endif
+
+extern void setupHELTEC();
+extern void loopHELTEC();
+size_t OledPrint(String msg);
+
+/*-------------------DEFINE LOG LEVEL----------------------*/
+#ifndef LOG_LEVEL_LCD
+#  define LOG_LEVEL_LCD LOG_LEVEL_WARNING // Default to only display Notice level messages
+#endif
+#ifndef LOG_TO_LCD
+#  define LOG_TO_LCD false // Default to not display log messages on display
+#endif
+/*-------------------DEFINE MQTT TOPIC FOR CONFIG----------------------*/
+#define subjectMQTTtoHELTECset "/commands/MQTTtoHELTEC/config"
+
+// Simple construct for displaying message in lcd and oled displays
+
+#define displayPrint(...) \
+  if (lowpowermode < 2) heltecPrint(__VA_ARGS__) // only print if not in low power mode
+#define lpDisplayPrint(...) heltecPrint(__VA_ARGS__) // print in low power mode
+
+void heltecPrint(char*, char*, char*);
+void heltecPrint(char*, char*);
+void heltecPrint(char*);
+
+// This pattern was borrowed from HardwareSerial and modified to support the ssd1306 display
+
+class OledSerial : public Stream {
+private:
+  void displayIntro(int scale, int displayWidth, int displayHeight);
+
+public:
+  OledSerial(int);
+  void begin();
+  void drawLogo(int logoSize, int circle1X, int circle1Y, bool circle1, bool circle2, bool circle3, bool line1, bool line2, bool name);
+
+  SSD1306Wire* display;
+
+  int available(void); // Dummy functions
+  int peek(void); // Dummy functions
+  int read(void); // Dummy functions
+  void flush(void); // Dummy functions
+
+  void fillScreen(OLEDDISPLAY_COLOR); // fillScreen display and set color
+
+  size_t write(uint8_t);
+  size_t write(const uint8_t* buffer, size_t size);
+  inline size_t write(const char* buffer, size_t size) {
+    return write((uint8_t*)buffer, size);
+  }
+  inline size_t write(const char* s) {
+    return write((uint8_t*)s, strlen(s));
+  }
+  inline size_t write(unsigned long n) {
+    return write((uint8_t)n);
+  }
+  inline size_t write(long n) {
+    return write((uint8_t)n);
+  }
+  inline size_t write(unsigned int n) {
+    return write((uint8_t)n);
+  }
+  inline size_t write(int n) {
+    return write((uint8_t)n);
+  }
+
+protected:
+};
+
+extern OledSerial Oled;
+
+#endif