Initial commit: Simple Sensor firmware for Heltec T114 with BME280

- MeshCore-based Simple Sensor firmware
- Heltec T114 without display
- BME280 sensor support (temp/humidity/pressure)
- Radio: 868.856018 MHz, SF7, BW62.5 kHz, CR4/7
- 2-byte path hash
- PlatformIO project

variants/promicro/PromicroBoard.cpp

@@ -0,0 +1,25 @@
+#include <Arduino.h>
+#include <Wire.h>
+
+#include "PromicroBoard.h"
+
+void PromicroBoard::begin() {    
+    NRF52Board::begin();
+    btn_prev_state = HIGH;
+  
+    pinMode(PIN_VBAT_READ, INPUT);
+
+    #ifdef BUTTON_PIN
+      pinMode(BUTTON_PIN, INPUT_PULLUP);
+    #endif
+
+    #if defined(PIN_BOARD_SDA) && defined(PIN_BOARD_SCL)
+      Wire.setPins(PIN_BOARD_SDA, PIN_BOARD_SCL);
+    #endif
+    
+    Wire.begin();
+
+    pinMode(SX126X_POWER_EN, OUTPUT);
+    digitalWrite(SX126X_POWER_EN, HIGH);
+    delay(10);   // give sx1262 some time to power up
+}