Added default temperature from ESP32 MCU and NRF52 MCU

Added NRF52Board.h and NRF52Board.cpp
Modified NRF52 variants to extend from NRF52Board to share common feature

src/MeshCore.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <stdint.h>
+#include <math.h>
 
 #define MAX_HASH_SIZE        8
 #define PUB_KEY_SIZE        32
@@ -42,6 +43,7 @@ namespace mesh {
 class MainBoard {
 public:
   virtual uint16_t getBattMilliVolts() = 0;
+  virtual float getMCUTemperature() { return NAN; }
   virtual bool setAdcMultiplier(float multiplier) { return false; };
   virtual float getAdcMultiplier() const { return 0.0f; }
   virtual const char* getManufacturerName() const = 0;

src/helpers/ESP32Board.h

@@ -42,6 +42,11 @@ public:
   #endif
   }
 
+  // Temperature from ESP32 MCU
+  float getMCUTemperature() override {
+    return temperatureRead();
+  }
+
   uint8_t getStartupReason() const override { return startup_reason; }
 
 #if defined(P_LORA_TX_LED)

src/helpers/NRF52Board.cpp

@@ -0,0 +1,23 @@
+#if defined(NRF52_PLATFORM)
+#include "NRF52Board.h"
+
+// Temperature from NRF52 MCU
+float NRF52Board::getMCUTemperature() {
+  NRF_TEMP->TASKS_START = 1; // Start temperature measurement
+
+  long startTime = millis();  
+  while (NRF_TEMP->EVENTS_DATARDY == 0) { // Wait for completion. Should complete in 50us
+    if(millis() - startTime > 5) {  // To wait 5ms just in case
+      NRF_TEMP->TASKS_STOP = 1;
+      return NAN;
+    }
+  }
+  
+  NRF_TEMP->EVENTS_DATARDY = 0; // Clear event flag
+
+  int32_t temp = NRF_TEMP->TEMP; // In 0.25 *C units
+  NRF_TEMP->TASKS_STOP = 1;
+
+  return temp * 0.25f; // Convert to *C
+}
+#endif

src/helpers/NRF52Board.h

@@ -0,0 +1,12 @@
+#pragma once
+
+#include <Arduino.h>
+#include <MeshCore.h>
+
+#if defined(NRF52_PLATFORM)
+
+class NRF52Board : public mesh::MainBoard {
+public:
+  float getMCUTemperature() override;
+};
+#endif