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/xiao_rp2040/XiaoRP2040Board.h

@@ -0,0 +1,60 @@
+#pragma once
+
+#include <Arduino.h>
+#include <MeshCore.h>
+
+/*
+ * This board has no built-in way to read battery voltage.
+ * Nevertheless it's very easy to make it work, you only require two 1% resistors.
+ * If your using the WIO SX1262 Addon for xaio, make sure you dont connect D0!
+ *
+ *    BAT+ -----+
+ *              |
+ *       VSYS --+ -/\/\/\/\- --+
+ *                   200k      |
+ *                             +-- D0
+ *                             |
+ *        GND --+ -/\/\/\/\- --+
+ *              |    100k
+ *    BAT- -----+
+ */
+#define PIN_VBAT_READ     26 // D0
+#define BATTERY_SAMPLES   8
+#define ADC_MULTIPLIER    (3.0f * 3.3f * 1000)
+
+class XiaoRP2040Board : public mesh::MainBoard {
+protected:
+  uint8_t startup_reason;
+
+public:
+  void begin();
+  uint8_t getStartupReason() const override { return startup_reason; }
+
+#ifdef P_LORA_TX_LED
+  void onBeforeTransmit() override { digitalWrite(P_LORA_TX_LED, HIGH); }
+  void onAfterTransmit() override { digitalWrite(P_LORA_TX_LED, LOW); }
+#endif
+
+
+  uint16_t getBattMilliVolts() override {
+#if defined(PIN_VBAT_READ) && defined(ADC_MULTIPLIER)
+    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_MULTIPLIER * raw) / 4096;
+#else
+    return 0;
+#endif
+  }
+
+  const char *getManufacturerName() const override { return "Xiao RP2040"; }
+
+  void reboot() override { rp2040.reboot(); }
+
+  bool startOTAUpdate(const char *id, char reply[]) override;
+};