Refactor RSSI Scan

lib/scan/scan.cpp

@@ -0,0 +1,69 @@
+#ifndef LORASA_CORE_CPP
+#define LORASA_CORE_CPP
+
+#include "scan.h"
+#include <cstdint>
+#include <cstring>
+#include <stdlib.h>
+
+float Scan::getRSSI() { return 0.1; }
+
+uint16_t Scan::rssiMethod(uint16_t *result)
+{
+    memset(result, 0, res_size * sizeof(uint16_t));
+    int result_index = 0;
+
+    //
+    uint16_t max_signal = 65535;
+    // N of samples
+    for (int r = 0; r < SAMPLES_RSSI; r++)
+    {
+        float rssi = getRSSI();
+        if (rssi < -65535)
+            rssi = -65535;
+
+        uint16_t abs_rssi = abs(rssi);
+        if (abs_rssi < max_signal)
+        {
+            max_signal = abs_rssi;
+        }
+        // ToDO: check if 4 is correct value for 33 power bins
+        // Now we have more space because we are ignoring low dB values
+        // we can  / 3 default 4
+        if (RSSI_OUTPUT_FORMULA == 1)
+        {
+            result_index =
+                /// still not clear formula but it works
+                uint8_t(abs(rssi) / 4);
+        }
+        else if (RSSI_OUTPUT_FORMULA == 2)
+        {
+            if (rssi > HI_RSSI_THRESHOLD)
+            {
+                rssi = HI_RSSI_THRESHOLD;
+            }
+            else if (rssi < LO_RSSI_THRESHOLD)
+            {
+                rssi = LO_RSSI_THRESHOLD;
+            }
+
+            result_index = uint8_t((HI_RSSI_THRESHOLD - rssi) * scale);
+        }
+
+        if (result_index >= res_size)
+        {
+            // Maximum index possible
+            result_index = res_size - 1;
+        }
+
+        LOG("RSSI: %f IDX: %d\n", rssi, result_index);
+        if (result[result_index] == 0 || result[result_index] > abs_rssi)
+        {
+            result[result_index] = abs_rssi;
+        }
+    }
+
+    return max_signal;
+}
+
+#endif

lib/scan/scan.h

@@ -0,0 +1,46 @@
+#include <cstdint>
+#include <stdlib.h>
+
+#ifndef LORASA_CORE_H
+
+#define LORASA_CORE_H
+
+#ifdef PRINT_DEBUG
+#define LOG(args...) Serial.printf(args...)
+#define LOG_IF(cond, args...)                                                            \
+    if (cond)                                                                            \
+    LOG(args...)
+#elif !defined(LOG)
+#define LOG(args...)
+#define LOG_IF(cond, args...)
+#endif
+
+// Output Pixel Formula
+// 1 = rssi / 4, 2 = (rssi / 2) - 22 or 20
+constexpr int RSSI_OUTPUT_FORMULA = 2;
+
+// based on the formula for RSSI_OUTPUT_FORMULA == 2
+// -2 * (22 + RADIOLIB_SX126X_SPECTRAL_SCAN_RES_SIZE) < rssi =< -44
+// practice may require a better pair of thresholds
+constexpr float HI_RSSI_THRESHOLD = -44.0;
+constexpr float LO_RSSI_THRESHOLD = HI_RSSI_THRESHOLD - 66;
+
+// number of samples for RSSI method
+#define SAMPLES_RSSI 12 // 21 //
+
+struct Scan
+{
+    Scan(int sz)
+        : res_size(sz), scale((float)sz / (HI_RSSI_THRESHOLD - LO_RSSI_THRESHOLD + 0.1))
+    {
+    }
+
+    virtual float getRSSI();
+
+    uint16_t rssiMethod(uint16_t *result);
+
+    int res_size;
+    float scale;
+};
+
+#endif