diff --git a/external/SleepTk/SleepTk.py b/external/SleepTk/SleepTk.py
index 56bbf39..e88dd70 100644
--- a/external/SleepTk/SleepTk.py
+++ b/external/SleepTk/SleepTk.py
@@ -500,13 +500,13 @@ class SleepTkApp():
         _STORE_FREQ seconds"""
         if self._currently_tracking:
             buff = self._buff
-            xyz = wasp.watch.accel.read_xyz()
+            xyz = wasp.watch.accel.accel_xyz()
             if xyz == (0, 0, 0):
                 wasp.watch.accel.reset()
-                xyz = wasp.watch.accel.read_xyz()
-            buff[0] += xyz[0]
-            buff[1] += xyz[1]
-            buff[2] += xyz[2]
+                xyz = wasp.watch.accel.accel_xyz()
+            buff[0] += xyz[1]
+            buff[1] += xyz[0]
+            buff[2] -= xyz[2]
             self._data_point_nb += 1
 
             # add alarm to log accel data in _FREQ seconds