Expose acceleration data

Signed-off-by: Francesco Gazzetta <fgaz@fgaz.me>

wasp/boards/simulator/watch.py

@@ -48,6 +48,10 @@ class Accelerometer:
     def steps(self, value):
         self.reset()
 
+    def accel_xyz(self):
+        # TODO randomly alter the values over time
+        return (0,0,0)
+
 class Backlight(object):
     def __init__(self, level=1):
         pass

wasp/drivers/bma421.py

@@ -49,3 +49,7 @@ class BMA421:
         if value != 0:
             raise ValueError()
         self._dev.reset_step_counter()
+
+    def accel_xyz(self):
+        """Return a triple with acceleration values"""
+        return self._dev.read_accel_xyz()