Enable stage coordinate zeroing

openflexure_microscope/stage/base.py

@@ -74,6 +74,11 @@ class BaseStage(metaclass=ABCMeta):
         """Make an absolute move to a position"""
         pass
 
+    @abstractmethod
+    def zero_position(self):
+        """Set the current position to zero"""
+        pass
+
     @abstractmethod
     def close(self):
         """Cleanly close communication with the stage"""

openflexure_microscope/stage/mock.py

@@ -96,5 +96,9 @@ class MockStage(BaseStage):
         self._position = list(final)
         logging.debug(f"New position: {self._position}")
 
+    def zero_position(self):
+        """Set the current position to zero"""
+        self._position = [0, 0, 0]
+
     def close(self):
         pass

openflexure_microscope/stage/sanga.py

@@ -147,6 +147,11 @@ class SangaStage(BaseStage):
         with self.lock:
             self.board.move_abs(final, **kwargs)
 
+    def zero_position(self):
+        """Set the current position to zero"""
+        with self.lock:
+            self.board.zero_position()
+
     def close(self):
         """Cleanly close communication with the stage"""
         if hasattr(self, "board"):

openflexure_microscope/stage/sangaboard/sangaboard.py

@@ -52,7 +52,7 @@ class Sangaboard(ExtensibleSerialInstrument):
 
     # These are the settings for the sangaboards serial port, and can usually be left as default.
     port_settings = {
-        "baudrate": 115200,
+        "baudrate": 115_200,
         "bytesize": EIGHTBITS,
         "parity": PARITY_NONE,
         "stopbits": STOPBITS_ONE,
@@ -215,6 +215,10 @@ class Sangaboard(ExtensibleSerialInstrument):
         """De-energise the stepper motor coils"""
         self.query("release")
 
+    def zero_position(self):
+        """Set the current position to zero"""
+        self.query("zero")
+
     def move_abs(self, final, **kwargs):
         """Make an absolute move to a position