Oops, fix min_slope_position/min_slope_postion -> min_slope_ratio typo.

[pyafm.git] / pyafm / afm.py

diff --git a/pyafm/afm.py b/pyafm/afm.py
index ada5b130b21c22addbb88e6e9f9996d9b04e8a03..0c89df9da1e8fae7e2d026800956f3cf4cb96653 100644 (file)
--- a/pyafm/afm.py
+++ b/pyafm/afm.py
@@ -62,7 +62,8 @@ class AFM (object):
         if hasattr(self.temperature, 'get_temperature'):
             return self.temperature.get_temperature()
 
-    def move_just_onto_surface(self, depth=-50e-9, setpoint=2, far=200):
+    def move_just_onto_surface(self, depth=-50e-9, setpoint=2,
+                               min_slope_ratio=10, far=200):
         """Position the AFM tip close to the surface.
 
         Uses `.piezo.get_surface_position()` to pinpoint the position
@@ -92,15 +93,18 @@ class AFM (object):
         _LOG.debug("see if we're starting near the surface")
         try:
             pos = self.piezo.get_surface_position(
-                axis_name=self.axis_name, max_deflection=target_def)
+                axis_name=self.axis_name, max_deflection=target_def,
+                min_slope_ratio=min_slope_ratio)
         except _FlatFit, e:
             _LOG.info(e)
             pos = self._stepper_approach_again(
-                target_deflection=target_def, far=far)
+                target_deflection=target_def, min_slope_ratio=min_slope_ratio,
+                far=far)
         except _SurfaceError, e:
             _LOG.info(e)
             pos = self._stepper_approach_again(
-                target_deflection=target_def, far=far)
+                target_deflection=target_def, min_slope_ratio=min_slope_ratio,
+                far=far)
 
         pos_m = _convert_bits_to_meters(axis.config, pos)
         _LOG.debug('located surface at stepper %d, piezo %d (%g m)'
@@ -112,7 +116,8 @@ class AFM (object):
             self.stepper.step_relative(-1, backlash_safe=True)
             try:
                 pos = self.piezo.get_surface_position(
-                    axis_name=self.axis_name, max_deflection=target_def)
+                    axis_name=self.axis_name, max_deflection=target_def,
+                    min_slope_ratio=min_slope_ratio)
             except _FlatFit, e:
                 _LOG.debug(e)
                 continue
@@ -124,7 +129,8 @@ class AFM (object):
             self.stepper.step_relative(1)
             try:
                 pos = self.piezo.get_surface_position(
-                    axis_name=self.axis_name, max_deflection=target_def)
+                    axis_name=self.axis_name, max_deflection=target_def,
+                    min_slope_ratio=min_slope_ratio)
             except _FlatFit, e:
                 _LOG.debug(e)
                 continue
@@ -143,27 +149,19 @@ class AFM (object):
             % (depth, self.stepper.position, target, target_m))
 
 
-    def _stepper_approach_again(self, target_deflection, far):
+    def _stepper_approach_again(self, target_deflection, min_slope_ratio, far):
         _LOG.info('back off %d half steps and approach until deflection > %g'
                  % (far, target_deflection))
-
         # back away
         self.stepper.step_relative(-far, backlash_safe=True)
-
-        cd = self.piezo.read_deflection()  # cd = current deflection in bits
-        _LOG.debug('single stepping approach')
-        while cd < target_deflection:
-            _LOG.debug('deflection %g < setpoint %g.  step closer'
-                      % (cd, target_deflection))
-            self.stepper.single_step(1)  # step in
-            cd = self.piezo.read_deflection()
-
+        self.stepper_approach(target_deflection=target_deflection)
         for i in range(2*max(1, self.stepper.backlash)):
             _LOG.debug(
                 'additional surface location attempt (stepping backwards)')
             try:
                 pos = self.piezo.get_surface_position(
-                    axis_name=self.axis_name, max_deflection=target_deflection)
+                    axis_name=self.axis_name, max_deflection=target_deflection,
+                    min_slope_ratio=min_slope_ratio)
                 return pos
             except _SurfaceError, e:
                 _LOG.info(e)
@@ -171,3 +169,14 @@ class AFM (object):
         _LOG.debug('giving up on finding the surface')
         _LOG.warn(e)
         raise e
+
+    def stepper_approach(self, target_deflection):
+        _LOG.info('approach with stepper until deflection > {}'.format(
+                target_deflection))
+        cd = self.piezo.read_deflection()  # cd = current deflection in bits
+        _LOG.debug('single stepping approach')
+        while cd < target_deflection:
+            _LOG.debug('deflection {} < setpoint {}.  step closer'.format(
+                    cd, target_deflection))
+            self.stepper.single_step(1)  # step in
+            cd = self.piezo.read_deflection()