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.h

@@ -0,0 +1,79 @@
+#pragma once
+
+#include <MeshCore.h>
+#include <Arduino.h>
+#include <helpers/NRF52Board.h>
+
+#define P_LORA_NSS 13 //P1.13 45
+#define P_LORA_DIO_1 11 //P0.10 10
+#define P_LORA_RESET 10 //P0.09 9
+#define P_LORA_BUSY  16 //P0.29 29
+#define P_LORA_MISO  15 //P0.02 2
+#define P_LORA_SCLK  12 //P1.11 43
+#define P_LORA_MOSI  14 //P1.15 47
+#define SX126X_POWER_EN 21 //P0.13 13
+#define SX126X_RXEN 2 //P0.17
+#define SX126X_TXEN RADIOLIB_NC
+#define SX126X_DIO2_AS_RF_SWITCH  true
+#define SX126X_DIO3_TCXO_VOLTAGE (1.8f)
+
+#define  PIN_VBAT_READ 17
+#define  ADC_MULTIPLIER   (1.815f) // dependent on voltage divider resistors. TODO: more accurate battery tracking
+
+class PromicroBoard : public NRF52BoardDCDC {
+protected:
+  uint8_t btn_prev_state;
+  float adc_mult = ADC_MULTIPLIER;
+
+public:
+  PromicroBoard() : NRF52Board("ProMicro_OTA") {}
+  void begin();
+
+  #define BATTERY_SAMPLES 8
+
+  uint16_t getBattMilliVolts() override {
+    analogReadResolution(12);
+
+    uint32_t raw = 0;
+    for (int i = 0; i < BATTERY_SAMPLES; i++) {
+      raw += analogRead(PIN_VBAT_READ);
+    }
+    raw = raw / BATTERY_SAMPLES;
+    return (adc_mult * raw);
+  }
+
+  bool setAdcMultiplier(float multiplier) override {
+    if (multiplier == 0.0f) {
+      adc_mult = ADC_MULTIPLIER;}
+    else {
+      adc_mult = multiplier;
+    }
+    return true;
+  }
+  float getAdcMultiplier() const override {
+    if (adc_mult == 0.0f) {
+      return ADC_MULTIPLIER;
+    } else {
+      return adc_mult;
+    }
+  }
+
+  const char* getManufacturerName() const override {
+    return "ProMicro DIY";
+  }
+
+  int buttonStateChanged() {
+    #ifdef BUTTON_PIN
+      uint8_t v = digitalRead(BUTTON_PIN);
+      if (v != btn_prev_state) {
+        btn_prev_state = v;
+        return (v == LOW) ? 1 : -1;
+      }
+    #endif
+      return 0;
+  }
+
+  void powerOff() override {
+    sd_power_system_off();
+  }
+};