Add Esp32 (serial) vehicle to pycar

.vscode/launch.json

@@ -10,7 +10,8 @@
             "request": "launch",
             "module": "car",
             "env": {
-                "CAR_VEHICLE": "CAR_MOCK",
+                "CAR_VEHICLE": "VEHICLE_MOCK",
+                // "CAR_VEHICLE": "VEHICLE_SERIAL",
                 // "CAR_LIDAR": "/dev/tty.usbserial-0001",
                 "CAR_LIDAR": "LIDAR_MOCK"
             }

esp32/README.md

@@ -10,6 +10,8 @@ The protocol specification is as follows, assuming an array of bytes:
 | 0 | 0 if Calibrating a servo. Higher values indicates channel number to set duty cycle on. |
 | 1 | If byte 0 = 0: number of servos to calibrate. Else, the new duty cycle value for the channel specified in byte 0. |
 
+When setting the duty cycle, the current min angle is 0, and the max angle is 255, which allows the entire byte to be used for setting the duty cycle.
+
 The table below describes the byte format for calibrating a servo. This array of bytes can be repeated for the given number of servos in byte 1:
 
 | Byte Number   | Value Description |
@@ -20,3 +22,7 @@ The table below describes the byte format for calibrating a servo. This array of
 The min/max pulse widths are hardcoded to 1000us/2000us respectively. 
 
 At the end of each loop, the entire array will be read, to flush any data that may cause issues later.
+
+Upcoming (TODO):
+- Use bit shift to allow 12 bits to be used for the duty cycle range, as there can only be a max of 16 channels anyway (4 bits).
+- Consider protobuf or msgpack for serialisation format, for more advanced use cases, and more maintainable communication formats (currently changing the message format will require changes to the entire protocol)

pycar/src/car/control/gpio/abstract_vehicle.py

@@ -0,0 +1,26 @@
+from abc import ABC, abstractmethod, abstractproperty
+
+class AbstractVehicle(ABC):
+    
+    @abstractmethod
+    @property
+    def throttle(self):
+        pass
+
+    @abstractmethod
+    @throttle.setter
+    def throttle(self):
+        pass
+
+    @abstractmethod
+    @property
+    def steering(self):
+        pass
+
+    @abstractmethod
+    @steering.setter
+    def throttle(self):
+        pass
+
+    def stop(self):
+        pass

pycar/src/car/control/gpio/factory.py

@@ -1,18 +1,25 @@
+from car.control.gpio.abstract_vehicle import AbstractVehicle
+from car.control.gpio.serial_vehicle import SerialVehicle
 from .mockvehicle import MockVehicle
 import os
 
 
-def get_vehicle(motor_pin=19, steering_pin=18):
+# TODO: Remove need for motor/steering pin, instead retrieve from env variable.
+# TODO: Dependency injectino in python?
+def get_vehicle(motor_pin=19, steering_pin=18) -> AbstractVehicle:
     ENV_CAR = None if 'CAR_VEHICLE' not in os.environ else os.environ['CAR_VEHICLE']
-    if ENV_CAR == "CAR_2D":
+    if ENV_CAR == "VEHICLE_2D":
         try:
             from .vehicle import Vehicle
             return Vehicle(motor_pin, steering_pin)
         except ImportError:
             print(
                 'Could not import CAR_2D vehicle. Have you installed the GPIOZERO package?')
-    elif ENV_CAR == "CAR_MOCK":
+    elif ENV_CAR == "VEHICLE_MOCK":
-        return MockVehicle(motor_pin, steering_pin)
+        return MockVehicle()
+    elif ENV_CAR == "VEHICLE_SERIAL":
+        # TODO: Pins in environment variables.
+        return SerialVehicle()
     else:
         print('No valid vehicle found. Have you set the CAR_VEHICLE environment variable?')
         return None

pycar/src/car/control/gpio/mockvehicle.py

@@ -1,10 +1,11 @@
 
 
-# A dummy vehicle class to use when 
+# A dummy vehicle class to use when testing/not connected to a real device.
-class MockVehicle:
+from car.control.gpio.abstract_vehicle import AbstractVehicle
-    def __init__(self, motor_pin=19, servo_pin=18):
+
-        self.motor_pin = motor_pin
+
-        self.steering_pin = servo_pin
+class MockVehicle(AbstractVehicle):
+    def __init__(self):
         print('Using Mock Vehicle')
 
     @property
@@ -23,21 +24,5 @@ class MockVehicle:
     def steering(self, value):
         self._steering = value
 
-    @property
-    def motor_pin(self):
-        return self._motor_pin
-
-    @motor_pin.setter
-    def motor_pin(self, value):
-        self._motor_pin = value
-
-    @property
-    def steering_pin(self):
-        return self._steering_pin
-
-    @steering_pin.setter
-    def steering_pin(self, value):
-        self._steering_pin = value
-
     def stop(self):
         self.throttle = 0

pycar/src/car/control/gpio/recording_vehicle_decorator.py

@@ -1,11 +1,12 @@
 import datetime
+from .abstract_vehicle import AbstractVehicle
 
 
-class VehicleRecordingDecorator:
+class VehicleRecordingDecorator(AbstractVehicle):
     def __init__(self, vehicle):
         """
         A decorator for a vehicle object to record the changes in steering/throttle.
-        This will be recorded to memory, and will save to the given file when save is called.
+        This will be recorded to memory, and will save to the given file when save_data is called.
 
         Parameters
         ----------
@@ -66,21 +67,5 @@ class VehicleRecordingDecorator:
                 's,' + str(value) + ',' + datetime.datetime.now().isoformat(sep=' ', timespec='seconds'))
         self._vehicle.steering = value
 
-    @property
-    def motor_pin(self):
-        return self._vehicle.motor_pin
-
-    @motor_pin.setter
-    def motor_pin(self, value):
-        self._vehicle.motor_pin = value
-
-    @property
-    def steering_pin(self):
-        return self._vehicle.steering_pin
-
-    @steering_pin.setter
-    def steering_pin(self, value):
-        self._vehicle.steering_pin = value
-
     def stop(self):
         self.throttle = 0

pycar/src/car/control/gpio/serial_vehicle.py

@@ -0,0 +1,42 @@
+from .abstract_vehicle import AbstractVehicle
+from serial import Serial
+
+STEERING_CHANNEL = 1
+THROTTLE_CHANNEL = 2
+
+
+class SerialVehicle(AbstractVehicle):
+
+    def __init__(self, serial_port='/dev/ttyUSB0', steering_pin=12, throttle_pin=14):
+        self.serial_port = Serial(port=serial_port, baudrate=115200)
+
+        # Initialise the channels and pins on esp32.
+        self._init_esp32_pwm(steering_pin, throttle_pin)
+        self.throttle = 0
+        self.steering = 0
+
+    @property
+    def throttle(self) -> float:
+        return self.throttle
+
+    @throttle.setter
+    def throttle(self, new_throttle: float):
+        self.throttle = new_throttle
+        self._set_servo_value(THROTTLE_CHANNEL, new_throttle)
+
+    @property
+    def steering(self) -> float:
+        return self.steering
+
+    @steering.setter
+    def steering(self, new_steering: float):
+        self.steering = new_steering
+        self._set_servo_value(STEERING_CHANNEL, new_steering)
+
+    def _set_servo_value(self, channel, value):
+        # Scale the value to a byte, as 0-255 is the angle range for the esp32 servo.
+        self.serial_port.write(bytes[channel, (value + 1) / 2 * 255])
+
+    def _init_esp32_pwm(self, steering_pin, throttle_pin):
+        self.serial_port.write(bytes([0, 2, STEERING_CHANNEL,
+                                      steering_pin, THROTTLE_CHANNEL, throttle_pin]))

pycar/src/car/control/gpio/vehicle.py

@@ -1,3 +1,4 @@
+from .abstract_vehicle import AbstractVehicle
 from gpiozero import Servo, Device
 from gpiozero.pins.pigpio import PiGPIOFactory
 import subprocess
@@ -29,7 +30,7 @@ def _is_pin_valid(pin):
 # two servos for controls (e.g. drone, dog)
 
 
-class Vehicle:
+class Vehicle(AbstractVehicle):
     def __init__(self, motor_pin=19, servo_pin=18):
         subprocess.call(['pigpiod'])
         Device.pin_factory = PiGPIOFactory()