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/sensecap_indicator-espnow/target.cpp

@@ -0,0 +1,56 @@
+#include <Arduino.h>
+#include "target.h"
+#include <helpers/ArduinoHelpers.h>
+
+ESP32Board board;
+
+ESPNOWRadio radio_driver;
+
+ESP32RTCClock rtc_clock;
+#if defined(ENV_INCLUDE_GPS)
+MicroNMEALocationProvider nmea = MicroNMEALocationProvider(Serial1, (mesh::RTCClock*)&rtc_clock);
+EnvironmentSensorManager sensors = EnvironmentSensorManager(nmea);
+#else
+EnvironmentSensorManager sensors = EnvironmentSensorManager();
+#endif
+
+#ifdef DISPLAY_CLASS
+  DISPLAY_CLASS display;
+  #ifdef PIN_USER_BTN
+  MomentaryButton user_btn(PIN_USER_BTN, 1000, true, true);
+  #endif
+#endif
+
+bool radio_init() {
+  rtc_clock.begin();
+
+  radio_driver.init();
+
+  return true;  // success
+}
+
+uint32_t radio_get_rng_seed() {
+  return millis() + radio_driver.intID();  // TODO: where to get some entropy?
+}
+
+void radio_set_params(float freq, float bw, uint8_t sf, uint8_t cr) {
+  // no-op
+}
+
+void radio_set_tx_power(int8_t dbm) {
+  radio_driver.setTxPower(dbm);
+}
+
+// NOTE: as we are using the WiFi radio, the ESP_IDF will have enabled hardware RNG:
+//    https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/system/random.html
+class ESP_RNG : public mesh::RNG {
+public:
+  void random(uint8_t* dest, size_t sz) override {
+    esp_fill_random(dest, sz);
+  }
+};
+
+mesh::LocalIdentity radio_new_identity() {
+  ESP_RNG rng;
+  return mesh::LocalIdentity(&rng);  // create new random identity
+}