* new ui/DisplayDriver classes (just SSD1306Display impl for now)

* companion radio: now with optional UITask (enabled by DISPLAY_CLASS config in target/env)

src/helpers/HeltecV3Board.h

@@ -17,6 +17,7 @@
 #define  PIN_ADC_CTRL_ACTIVE    LOW
 #define  PIN_ADC_CTRL_INACTIVE  HIGH
 #define  PIN_LED_BUILTIN 35
+#define  PIN_VEXT_EN     36
 
 #include "ESP32Board.h"
 
@@ -28,6 +29,7 @@ public:
     ESP32Board::begin();
 
     pinMode(PIN_ADC_CTRL, OUTPUT);
+    //pinMode(PIN_VEXT_EN, OUTPUT);
 
     esp_reset_reason_t reason = esp_reset_reason();
     if (reason == ESP_RST_DEEPSLEEP) {

src/helpers/ui/DisplayDriver.h

@@ -0,0 +1,27 @@
+#pragma once
+
+#include <stdint.h>
+
+class DisplayDriver {
+  int _w, _h;
+protected:
+  DisplayDriver(int w, int h) { _w = w; _h = h; }
+public:
+  enum Color { DARK, LIGHT };
+
+  int width() const { return _w; }
+  int height() const { return _h; }
+
+  virtual bool isOn() = 0;
+  virtual void turnOn() = 0;
+  virtual void turnOff() = 0;
+  virtual void startFrame(Color bkg = DARK) = 0;
+  virtual void setTextSize(int sz) = 0;
+  virtual void setColor(Color c) = 0;
+  virtual void setCursor(int x, int y) = 0;
+  virtual void print(const char* str) = 0;
+  virtual void fillRect(int x, int y, int w, int h) = 0;
+  virtual void drawRect(int x, int y, int w, int h) = 0;
+  virtual void drawXbm(int x, int y, const uint8_t* bits, int w, int h) = 0;
+  virtual void endFrame() = 0;
+};

src/helpers/ui/SSD1306Display.cpp

@@ -0,0 +1,56 @@
+#include "SSD1306Display.h"
+
+bool SSD1306Display::begin() {
+  return display.begin(SSD1306_SWITCHCAPVCC, DISPLAY_ADDRESS);
+}
+
+void SSD1306Display::turnOn() {
+  display.ssd1306_command(SSD1306_DISPLAYON);
+  _isOn = true;
+}
+
+void SSD1306Display::turnOff() {
+  display.ssd1306_command(SSD1306_DISPLAYOFF);
+  _isOn = false;
+}
+
+void SSD1306Display::startFrame(Color bkg) {
+  display.clearDisplay();  // TODO: apply 'bkg'
+  _color = SSD1306_WHITE;
+  display.setTextColor(_color);
+  display.setTextSize(1);
+  display.cp437(true);         // Use full 256 char 'Code Page 437' font
+}
+
+void SSD1306Display::setTextSize(int sz) {
+  display.setTextSize(sz);
+}
+
+void SSD1306Display::setColor(Color c) {
+  _color = (c == LIGHT) ? SSD1306_WHITE : SSD1306_BLACK;
+  display.setTextColor(_color);
+}
+
+void SSD1306Display::setCursor(int x, int y) {
+  display.setCursor(x, y);
+}
+
+void SSD1306Display::print(const char* str) {
+  display.print(str);
+}
+
+void SSD1306Display::fillRect(int x, int y, int w, int h) {
+  display.fillRect(x, y, w, h, _color);
+}
+
+void SSD1306Display::drawRect(int x, int y, int w, int h) {
+  display.drawRect(x, y, w, h, _color);
+}
+
+void SSD1306Display::drawXbm(int x, int y, const uint8_t* bits, int w, int h) {
+  display.drawBitmap(x, y, bits, w, h, SSD1306_WHITE);
+}
+
+void SSD1306Display::endFrame() {
+  display.display();
+}

src/helpers/ui/SSD1306Display.h

@@ -0,0 +1,37 @@
+#pragma once
+
+#include "DisplayDriver.h"
+#include <Wire.h>
+#include <Adafruit_GFX.h>
+#include <Adafruit_SSD1306.h>
+
+#ifndef PIN_OLED_RESET
+  #define PIN_OLED_RESET        21 // Reset pin # (or -1 if sharing Arduino reset pin)
+#endif
+
+#ifndef DISPLAY_ADDRESS
+  #define DISPLAY_ADDRESS   0x3C
+#endif
+
+class SSD1306Display : public DisplayDriver {
+  Adafruit_SSD1306 display;
+  bool _isOn;
+  uint8_t _color;
+
+public:
+  SSD1306Display() : DisplayDriver(128, 64), display(128, 64, &Wire, PIN_OLED_RESET) { _isOn = false; }
+  bool begin();
+
+  bool isOn() override { return _isOn; }
+  void turnOn() override;
+  void turnOff() override;
+  void startFrame(Color bkg = DARK) override;
+  void setTextSize(int sz) override;
+  void setColor(Color c) override;
+  void setCursor(int x, int y) override;
+  void print(const char* str) override;
+  void fillRect(int x, int y, int w, int h) override;
+  void drawRect(int x, int y, int w, int h) override;
+  void drawXbm(int x, int y, const uint8_t* bits, int w, int h) override;
+  void endFrame() override;
+};