Add heltec -v4-r8 board

variants/heltec_v4_r8/HeltecV4R8Board.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <Arduino.h>
+#include <driver/rtc_io.h>
+#include <helpers/ESP32Board.h>
+#include <helpers/RefCountedDigitalPin.h>
+#include "LoRaFEMControl.h"
+
+#ifndef ADC_MULTIPLIER
+  #define ADC_MULTIPLIER (4.9f * 1.035f)
+#endif
+
+class HeltecV4R8Board : public ESP32Board {
+protected:
+  float adc_mult = ADC_MULTIPLIER;
+
+public:
+  RefCountedDigitalPin periph_power;
+  LoRaFEMControl loRaFEMControl;
+
+  HeltecV4R8Board() : periph_power(PIN_VEXT_EN, PIN_VEXT_EN_ACTIVE) { }
+
+  void begin();
+  void onBeforeTransmit(void) override;
+  void onAfterTransmit(void) override;
+  void enterDeepSleep(uint32_t secs, int pin_wake_btn = -1);
+  void powerOff() override;
+  uint16_t getBattMilliVolts() override;
+  bool setAdcMultiplier(float multiplier) override {
+    if (multiplier == 0.0f) {
+      adc_mult = ADC_MULTIPLIER;
+    } else {
+      adc_mult = multiplier;
+    }
+    return true;
+  }
+  float getAdcMultiplier() const override { return adc_mult; }
+  const char* getManufacturerName() const override;
+};