manual focus control!

thanks https://github.com/xupsh/Vision-Zynq/blob/master/ov5640_init/OV5640.c#L249 :)

adafruit_pycamera/__init__.py

@@ -48,6 +48,8 @@
 _OV5640_CMD_TRIGGER_AUTOFOCUS = const(0x03)
 _OV5640_CMD_AUTO_AUTOFOCUS = const(0x04)
 _OV5640_CMD_RELEASE_FOCUS = const(0x08)
+_OV5640_CMD_AF_SET_VCM_STEP = const(0x1a)
+_OV5640_CMD_AF_GET_VCM_STEP = const(0x1b)
 
 _OV5640_CMD_MAIN = const(0x3022)
 _OV5640_CMD_ACK = const(0x3023)
@@ -493,6 +495,22 @@ def autofocus(self) -> list[int]:
         print(f"zones focused: {zone_focus}")
         return zone_focus
 
+    @property
+    def autofocus_vcm_step(self):
+        """Get the voice coil motor step location"""
+        if not self._send_autofocus_command(_OV5640_CMD_AF_GET_VCM_STEP, "get vcm step"):
+            return None
+        return self.read_camera_register(_OV5640_CMD_PARA4)
+
+    @autofocus_vcm_step.setter
+    def autofocus_vcm_step(self, step):
+        """Get the voice coil motor step location, from 0 to 255"""
+        if not (0 <= step <= 255):
+            raise RuntimeError("VCM step must be 0 to 255")
+        self.write_camera_register(_OV5640_CMD_PARA3, 0x00)
+        self.write_camera_register(_OV5640_CMD_PARA4, step)
+        self._send_autofocus_command(_OV5640_CMD_AF_SET_VCM_STEP, "set vcm step")
+
     def select_setting(self, setting_name):
         """For the point & shoot camera mode, control what setting is being set"""
         self._effect_label.color = 0xFFFFFF