Fix ganglion accel (brainflow-dev#150)

* fix ganglion bled accel * add wifi ganglion accel fixes * final fix from andrey
neuroidss · Apr 26, 2020 · 4d80b87 · 4d80b87
1 parent e51320c
commit 4d80b87
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Showing 4 changed files with 11 additions and 8 deletions.
diff --git a/src/board_controller/openbci/ganglion.cpp b/src/board_controller/openbci/ganglion.cpp
@@ -254,14 +254,16 @@ void Ganglion::read_thread ()
                 int last_digit = data.data[0] % 10;
                 switch (last_digit)
                 {
+                    // accel data is signed, so we must cast it to signed char
+                    // due to a known bug in ganglion firmware, we must swap x and z, and invert z.
                     case 0:
-                        accel_x = accel_scale * data.data[19];
+                        accel_z = -accel_scale * (char)data.data[19];
                         break;
                     case 1:
-                        accel_y = accel_scale * data.data[19];
+                        accel_y = accel_scale * (char)data.data[19];
                         break;
                     case 2:
-                        accel_z = accel_scale * data.data[19];
+                        accel_x = accel_scale * (char)data.data[19];
                         break;
                     default:
                         break;

diff --git a/src/board_controller/openbci/ganglion_wifi.cpp b/src/board_controller/openbci/ganglion_wifi.cpp
@@ -67,9 +67,10 @@ void GanglionWifi::read_thread ()
             if (b[32 + offset] == END_BYTE_STANDARD)
             {
                 // accel
-                package[5] = accel_scale * cast_16bit_to_int32 (b + 26 + offset);
-                package[6] = accel_scale * cast_16bit_to_int32 (b + 28 + offset);
-                package[7] = accel_scale * cast_16bit_to_int32 (b + 30 + offset);
+                // mistake in firmware in axis
+                package[5] = accel_scale * cast_16bit_to_int32 (b + 28 + offset);
+                package[6] = accel_scale * cast_16bit_to_int32 (b + 26 + offset);
+                package[7] = -accel_scale * cast_16bit_to_int32 (b + 30 + offset);
             }
             // place analog data
             if (b[32 + offset] == END_BYTE_ANALOG)

diff --git a/src/board_controller/openbci/inc/ganglion.h b/src/board_controller/openbci/inc/ganglion.h
@@ -17,7 +17,7 @@ class Ganglion : public Board
 
     bool is_valid;
 
-    float const accel_scale = 0.032f;
+    float const accel_scale = 0.016f;
     float const eeg_scale = (1.2f * 1000000) / (8388607.0f * 1.5f * 51.0f);
 
     volatile bool keep_alive;

diff --git a/src/board_controller/openbci/inc/ganglion_wifi.h b/src/board_controller/openbci/inc/ganglion_wifi.h
@@ -9,7 +9,7 @@
 
 class GanglionWifi : public OpenBCIWifiShieldBoard
 {
-    float const accel_scale = 0.032f;
+    float const accel_scale = (0.02f / 16.0f) / 1.25f; // 1.25 experimental number
     float const eeg_scale = (1.2f * 1000000) / (8388607.0f * 1.5f * 51.0f);
 
 protected: