Update Galea EDA calculation and available data

Fixes #784

Author: retiutut

src/board_controller/brainflow_boards.cpp

@@ -199,17 +199,17 @@ BrainFlowBoards::BrainFlowBoards()
         {"name", "GaleaAuxiliary"},
         {"sampling_rate", 50},
         {"package_num_channel", 0},
-        {"timestamp_channel", 17},
-        {"marker_channel", 18},
-        {"num_rows", 19},
-        {"battery_channel", 5},
-        {"eda_channels", {1}},
-        {"ppg_channels", {2, 3}},
-        {"accel_channels", {6, 7, 8}},
-        {"gyro_channels", {9, 10, 11}},
-        {"magnetometer_channels", {12, 13, 14}},
-        {"other_channels", {15, 16}},
-        {"temperature_channels", {4}}
+        {"timestamp_channel", 18},
+        {"marker_channel", 19},
+        {"num_rows", 20},
+        {"battery_channel", 6},
+        {"eda_channels", {1, 2}},
+        {"ppg_channels", {3, 4}},
+        {"accel_channels", {7, 8, 9}},
+        {"gyro_channels", {10, 11, 12}},
+        {"magnetometer_channels", {13, 14, 15}},
+        {"other_channels", {16, 17}},
+        {"temperature_channels", {5}}
     };
     brainflow_boards_json["boards"]["4"]["default"] =
     {

src/board_controller/openbci/galea.cpp

@@ -23,8 +23,7 @@ constexpr int Galea::max_num_packages;
 constexpr int Galea::max_transaction_size;
 constexpr int Galea::socket_timeout;
 
-Galea::Galea (struct BrainFlowInputParams params)
-    : Board ((int)BoardIds::GALEA_BOARD, params)
+Galea::Galea (struct BrainFlowInputParams params) : Board ((int)BoardIds::GALEA_BOARD, params)
 {
     socket = NULL;
     is_streaming = false;
@@ -477,9 +476,9 @@ void Galea::read_thread ()
                     uint16_t temperature = 0;
                     int32_t ppg_ir = 0;
                     int32_t ppg_red = 0;
-                    float eda;
+                    float eda_volts;
                     memcpy (&temperature, b + 78 + offset, 2);
-                    memcpy (&eda, b + 1 + offset, 4);
+                    memcpy (&eda_volts, b + 1 + offset, 4);
                     memcpy (&ppg_red, b + 80 + offset, 4);
                     memcpy (&ppg_ir, b + 84 + offset, 4);
                     // ppg
@@ -489,7 +488,13 @@ void Galea::read_thread ()
                         (double)ppg_ir;
                     // eda
                     aux_package[board_descr["auxiliary"]["eda_channels"][0].get<int> ()] =
-                        (double)eda;
+                        (double)eda_volts;
+                    constexpr double eda_coefficient_1 = 3724389.83278;
+                    constexpr double eda_coefficient_2 = 1652406.91447;
+                    double eda_conductance =
+                        1000000.0 / ((eda_coefficient_1 * eda_volts) - eda_coefficient_2);
+                    aux_package[board_descr["auxiliary"]["eda_channels"][1].get<int> ()] =
+                        eda_conductance;
                     // temperature
                     aux_package[board_descr["auxiliary"]["temperature_channels"][0].get<int> ()] =
                         temperature / 100.0;