Only reset port settings for motor on first start() (#125)

* Only reset port settings for motor on first start()

Don't allow the motor to start() if some other type of movement is currently running.  Additionally, remember what the current speed of a started motor is in order to not allow a serial command to be sent that effectively does nothing.

* Switch to enums because minimum python version is 3.7

Author: mutesplash

buildhat/motors.py

@@ -19,6 +19,7 @@ def __init__(self, port):
         self._default_speed = 20
         self.plimit(0.7)
         self.bias(0.3)
+        self.current_freerun_speed = 0
 
     def set_default_speed(self, default_speed):
         """Sets the default speed of the motor
@@ -34,18 +35,24 @@ def start(self, speed=None):
 
         :param speed: Speed ranging from -100 to 100
         """
+        if self.current_freerun_speed == speed:
+            # Already running at this speed, do nothing
+       	    return
+
         if speed is None:
             speed = self._default_speed
         else:
             if not (speed >= -100 and speed <= 100):
                 raise MotorException("Invalid Speed")
+        self.current_freerun_speed = speed
         cmd = "port {} ; pwm ; set {}\r".format(self.port, speed/100)
         self._write(cmd)
 
     def stop(self):
         """Stops motor"""
         cmd = "port {} ; off\r".format(self.port)
         self._write(cmd)
+        self.current_freerun_speed = 0
 
     def plimit(self, plimit):
         if not (plimit >= 0 and plimit <= 1):
@@ -57,6 +64,13 @@ def bias(self, bias):
             raise MotorException("bias should be 0 to 1")
         self._write("port {} ; bias {}\r".format(self.port, bias))
 
+
+class MotorRunmode(Enum):
+    NONE = 0
+    FREE = 1
+    DEGREES = 2
+    SECONDS = 3
+
 class Motor(Device):
     """Motor device
 
@@ -67,6 +81,7 @@ class Motor(Device):
     def __init__(self, port):
         super().__init__(port)
         self.default_speed = 20
+        self.current_freerun_speed = 0
         self.mode([(1,0),(2,0),(3,0)])
         self.plimit(0.7)
         self.bias(0.3)
@@ -75,6 +90,7 @@ def __init__(self, port):
         self._cvqueue = Condition()
         self.when_rotated = None
         self._oldpos = None
+        self.runmode = MotorRunmode.NONE
 
     def set_default_speed(self, default_speed):
         """Sets the default speed of the motor
@@ -91,6 +107,7 @@ def run_for_rotations(self, rotations, speed=None, blocking=True):
         :param rotations: Number of rotations
         :param speed: Speed ranging from -100 to 100
         """
+        self.runmode = MotorRunmode.DEGREES
         if speed is None:
             self.run_for_degrees(int(rotations * 360), self.default_speed, blocking)
         else:
@@ -99,6 +116,7 @@ def run_for_rotations(self, rotations, speed=None, blocking=True):
             self.run_for_degrees(int(rotations * 360), speed, blocking)
 
     def _run_for_degrees(self, degrees, speed):
+        self.runmode = MotorRunmode.DEGREES
         mul = 1
         if speed < 0:
             speed = abs(speed)
@@ -116,8 +134,10 @@ def _run_for_degrees(self, degrees, speed):
         if self._release:
             time.sleep(0.2)
             self.coast()
+        self.runmode = MotorRunmode.NONE
 
     def _run_to_position(self, degrees, speed, direction):
+        self.runmode = MotorRunmode.DEGREES
         data = self.get()
         pos = data[1]
         apos = data[2]
@@ -148,6 +168,7 @@ def _run_to_position(self, degrees, speed, direction):
         if self._release:
             time.sleep(0.2)
             self.coast()
+        self.runmode = MotorRunmode.NONE
 
     def run_for_degrees(self, degrees, speed=None, blocking=True):
         """Runs motor for N degrees
@@ -157,6 +178,7 @@ def run_for_degrees(self, degrees, speed=None, blocking=True):
         :param degrees: Number of degrees to rotate
         :param speed: Speed ranging from -100 to 100
         """
+        self.runmode = MotorRunmode.DEGREES
         if speed is None:
             speed = self.default_speed
         if not (speed >= -100 and speed <= 100):
@@ -174,6 +196,7 @@ def run_to_position(self, degrees, speed=None, blocking=True, direction="shortes
         :param degrees: Position in degrees
         :param speed: Speed ranging from 0 to 100
         """
+        self.runmode = MotorRunmode.DEGREES
         if speed is None:
             speed = self.default_speed
         if not (speed >= 0 and speed <= 100):
@@ -188,19 +211,22 @@ def run_to_position(self, degrees, speed=None, blocking=True, direction="shortes
             self._run_to_position(degrees, speed, direction)
 
     def _run_for_seconds(self, seconds, speed):
+        self.runmode = MotorRunmode.SECONDS
         cmd = "port {} ; combi 0 1 0 2 0 3 0 ; select 0 ; pid {} 0 0 s1 1 0 0.003 0.01 0 100; set pulse {} 0.0 {} 0\r".format(self.port, self.port, speed, seconds);
         self._write(cmd);
         with self._hat.pulsecond[self.port]:
             self._hat.pulsecond[self.port].wait()
         if self._release:
             self.coast()
+        self.runmode = MotorRunmode.NONE
 
     def run_for_seconds(self, seconds, speed=None, blocking=True):
         """Runs motor for N seconds
 
         :param seconds: Time in seconds
         :param speed: Speed ranging from -100 to 100
         """
+        self.runmode = MotorRunmode.SECONDS
         if speed is None:
             speed = self.default_speed
         if not (speed >= -100 and speed <= 100):
@@ -217,16 +243,31 @@ def start(self, speed=None):
 
         :param speed: Speed ranging from -100 to 100
         """
+        if self.runmode == MotorRunmode.FREE:
+            if self.current_freerun_speed == speed:
+                # Already running at this speed, do nothing
+                return
+        elif self.runmode != MotorRunmode.NONE:
+       	    # Motor is running some other mode, wait for it to stop or stop() it yourself
+       	    return
+
         if speed is None:
             speed = self.default_speed
         else:
             if not (speed >= -100 and speed <= 100):
                 raise MotorException("Invalid Speed")
-        cmd = "port {} ; combi 0 1 0 2 0 3 0 ; select 0 ; pid {} 0 0 s1 1 0 0.003 0.01 0 100; set {}\r".format(self.port, self.port, speed)
+        cmd = "port {} ; set {}\r".format(self.port, speed)
+        if self.runmode == MotorRunmode.NONE:
+            cmd = "port {} ; combi 0 1 0 2 0 3 0 ; select 0 ; pid {} 0 0 s1 1 0 0.003 0.01 0 100; set {}\r".format(self.port, self.port, speed)
+        self.runmode = MotorRunmode.FREE
+        self.current_freerun_speed = speed
         self._write(cmd)
 
+
     def stop(self):
         """Stops motor"""
+        self.runmode = MotorRunmode.NONE
+        self.current_freerun_speed = 0
         self.coast()
 
     def get_position(self):