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/heltec_t114/T114Board.cpp

@@ -0,0 +1,59 @@
+#include "T114Board.h"
+
+#include <Arduino.h>
+#include <Wire.h>
+
+#ifdef NRF52_POWER_MANAGEMENT
+// Static configuration for power management
+// Values come from variant.h defines
+const PowerMgtConfig power_config = {
+  .lpcomp_ain_channel = PWRMGT_LPCOMP_AIN,
+  .lpcomp_refsel = PWRMGT_LPCOMP_REFSEL,
+  .voltage_bootlock = PWRMGT_VOLTAGE_BOOTLOCK
+};
+
+void T114Board::initiateShutdown(uint8_t reason) {
+#if ENV_INCLUDE_GPS == 1
+  pinMode(GPS_EN, OUTPUT);
+  digitalWrite(GPS_EN, LOW);
+#endif
+  digitalWrite(SX126X_POWER_EN, LOW);
+
+  bool enable_lpcomp = (reason == SHUTDOWN_REASON_LOW_VOLTAGE ||
+                        reason == SHUTDOWN_REASON_BOOT_PROTECT);
+  pinMode(PIN_BAT_CTL, OUTPUT);
+  digitalWrite(PIN_BAT_CTL, enable_lpcomp ? HIGH : LOW);
+
+  if (enable_lpcomp) {
+    configureVoltageWake(power_config.lpcomp_ain_channel, power_config.lpcomp_refsel);
+  }
+
+  enterSystemOff(reason);
+}
+#endif // NRF52_POWER_MANAGEMENT
+
+void T114Board::begin() {
+  NRF52Board::begin();
+
+  pinMode(PIN_VBAT_READ, INPUT);
+
+#if defined(PIN_BOARD_SDA) && defined(PIN_BOARD_SCL)
+  Wire.setPins(PIN_BOARD_SDA, PIN_BOARD_SCL);
+#endif
+
+  Wire.begin();
+
+#ifdef P_LORA_TX_LED
+  pinMode(P_LORA_TX_LED, OUTPUT);
+  digitalWrite(P_LORA_TX_LED, HIGH);
+#endif
+
+  pinMode(SX126X_POWER_EN, OUTPUT);
+#ifdef NRF52_POWER_MANAGEMENT
+  // Boot voltage protection check (may not return if voltage too low)
+  // We need to call this after we configure SX126X_POWER_EN as output but before we pull high
+  checkBootVoltage(&power_config);
+#endif
+  digitalWrite(SX126X_POWER_EN, HIGH);
+  delay(10); // give sx1262 some time to power up
+}