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

src/helpers/RefCountedDigitalPin.h

@@ -0,0 +1,32 @@
+#pragma once
+
+#include <Arduino.h>
+
+class RefCountedDigitalPin {
+  uint8_t _pin;
+  int8_t _claims = 0;
+  uint8_t _active = 0;
+public:
+  RefCountedDigitalPin(uint8_t pin,uint8_t active=HIGH): _pin(pin), _active(active) { }
+
+  void begin() {
+    pinMode(_pin, OUTPUT);
+    digitalWrite(_pin, !_active);  // initial state
+  }
+
+  void claim() {
+    _claims++;
+    if (_claims > 0) {
+      digitalWrite(_pin, _active);
+    }
+  }
+
+  void release() {
+    if (_claims == 0) return; // avoid negative _claims
+
+    _claims--;
+    if (_claims == 0) {
+      digitalWrite(_pin, !_active);
+    }
+  }
+};