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

examples/simple_sensor/TimeSeriesData.cpp

@@ -0,0 +1,45 @@
+#include "TimeSeriesData.h"
+
+void TimeSeriesData::recordData(mesh::RTCClock* clock, float value) {
+  uint32_t now = clock->getCurrentTime();
+  if (now >= last_timestamp + interval_secs) {
+    last_timestamp = now;
+
+    data[next] = value;   // append to cycle table
+    next = (next + 1) % num_slots;
+  }
+}
+
+void TimeSeriesData::calcMinMaxAvg(mesh::RTCClock* clock, uint32_t start_secs_ago, uint32_t end_secs_ago, MinMaxAvg* dest, uint8_t channel, uint8_t lpp_type) const {
+  int i = next, n = num_slots;
+  uint32_t ago = clock->getCurrentTime() - last_timestamp;
+  int num_values = 0;
+  float total = 0.0f;
+
+  dest->_channel = channel;
+  dest->_lpp_type = lpp_type;
+
+  // start at most recet recording, back-track through to oldest
+  while (n > 0) {
+    n--;
+    i = (i + num_slots - 1) % num_slots;  // go back by one
+    if (ago >= end_secs_ago && ago < start_secs_ago) {   // filter by the desired time range
+      float v = data[i];
+      num_values++;
+      total += v;
+      if (num_values == 1) {
+        dest->_max = dest->_min = v;
+      } else {
+        if (v < dest->_min) dest->_min = v;
+        if (v > dest->_max) dest->_max = v;
+      }
+    }
+    ago += interval_secs;
+  }
+  // calc average
+  if (num_values > 0) {
+    dest->_avg = total / num_values;
+  } else {
+    dest->_max = dest->_min = dest->_avg = NAN;
+  }
+}