Chapter 10 code

2022-08-01 09:52:56 +01:00
parent 35358211ac
commit 7eff69d680
23 changed files with 1517 additions and 170 deletions
@@ -0,0 +1,35 @@
+import time
+import board
+import busio
+import robot
+from pid_controller import PIDController
+
+uart = busio.UART(board.GP12, board.GP13, baudrate=9600)
+
+
+## We'll set up a single distance sensor, and keep a set distance from an object
+robot.left_distance.distance_mode = 1
+robot.left_distance.start_ranging()
+
+distance_set_point = 10
+distance_controller = PIDController(-0.09, -0.02, -0.07)
+
+prev_time = time.monotonic()
+while True:
+  if robot.left_distance.data_ready:
+    distance = robot.left_distance.distance
+    error = distance_set_point - distance
+
+    current_time = time.monotonic()
+    speed = distance_controller.calculate(error, current_time - prev_time)
+    prev_time = current_time
+    # Control the motors with the speed
+    if abs(speed) < 0.35:
+      speed = 0
+    uart.write(f"{error},{speed},{distance_controller.integral},{distance_controller.derivative}\n".encode())
+    print(f"{error},{speed},{distance_controller.integral},{distance_controller.derivative}")
+    robot.set_left(speed)
+    robot.set_right(speed)
+    # reset the distance sensor
+    robot.left_distance.clear_interrupt()
+    time.sleep(0.05)
@@ -0,0 +1,20 @@
+class PIDController:
+    def __init__(self, kp, ki, kd, d_filter_gain=0.1):
+        self.kp = kp
+        self.ki = ki
+        self.kd = kd
+        self.d_filter_gain = d_filter_gain
+
+        self.integral = 0
+        self.error_prev = 0
+        self.derivative = 0
+
+    def calculate(self, error, dt):
+        self.integral += error * dt
+
+        # Add a low pass filter to the difference
+        difference = (error - self.error_prev) * self.d_filter_gain
+        self.error_prev += difference
+        self.derivative = difference / dt
+
+        return self.kp * error + self.ki * self.integral + self.kd * self.derivative
@@ -0,0 +1,77 @@
+import rp2pio
+import adafruit_pioasm
+import array
+
+program = """
+; use the osr for count
+; input pins c1 c2
+
+    set y, 0            ; clear y
+    mov osr, y          ; and clear osr
+read:
+    ; x will be the old value
+    ; y the new values
+    mov x, y            ; store old Y in x
+    in null, 32         ; Clear ISR - using y
+    in pins, 2          ; read two pins into y
+    mov y, isr
+    jmp x!=y, different ; Jump if its different
+    jmp read            ; otherwise loop back to read
+
+different:
+    ; x has old value, y has new.
+    ; extract the upper bit of X.
+    in x, 31             ; get bit 31 - old p1 (remember which direction it came in)
+    in null, 31         ; keep only 1 bit
+    mov x, isr          ; put this back in x
+    jmp !x, c1_old_zero
+
+c1_old_not_zero:
+    jmp pin, count_up
+    jmp count_down
+
+c1_old_zero:
+    jmp pin, count_down
+    ; fall through
+count_up:
+    ; for a clockwise move - we'll add 1 by inverting
+    mov x, ~ osr        ; store inverted OSR on x
+    jmp x--, fake       ; use jump to take off 1
+fake:
+    mov x, ~ x          ; invert back
+    jmp send
+count_down:
+    ; for a clockwise move, just take one off
+    mov x, osr          ; store osr in x
+    jmp x--, send       ; dec and send
+send:
+    ; send x.
+    mov isr, x          ; send it
+    push noblock        ; put ISR into input FIFO
+    mov osr, x          ; put X back in OSR
+    jmp read            ; loop back
+"""
+
+assembled = adafruit_pioasm.assemble(program)
+
+
+class QuadratureEncoder:
+    def __init__(self, first_pin, second_pin, reversed=False):
+        """Encoder with 2 pins. Must use sequential pins on the board"""
+        self.sm = rp2pio.StateMachine(
+            assembled,
+            frequency=0,
+            first_in_pin=first_pin,
+            jmp_pin=second_pin,
+            in_pin_count=2,
+        )
+        self.reversed = reversed
+        self._buffer = array.array("i", [0])
+
+    def read(self):
+        while self.sm.in_waiting:
+            self.sm.readinto(self._buffer)
+        if self.reversed:
+            return -self._buffer[0]
+        else:
+            return self._buffer[0]
@@ -0,0 +1,52 @@
+import board
+import pwmio
+import pio_encoder
+import busio
+import adafruit_vl53l1x
+
+
+motor_A1 = pwmio.PWMOut(board.GP17)
+motor_A2 = pwmio.PWMOut(board.GP16)
+motor_B1 = pwmio.PWMOut(board.GP18)
+motor_B2 = pwmio.PWMOut(board.GP19)
+
+right_motor = motor_A1, motor_A2
+left_motor = motor_B1, motor_B2
+
+right_encoder = pio_encoder.QuadratureEncoder(board.GP20, board.GP21, reversed=True)
+left_encoder = pio_encoder.QuadratureEncoder(board.GP26, board.GP27)
+
+i2c0 = busio.I2C(sda=board.GP0, scl=board.GP1)
+i2c1 = busio.I2C(sda=board.GP2, scl=board.GP3)
+
+left_distance = adafruit_vl53l1x.VL53L1X(i2c0)
+right_distance = adafruit_vl53l1x.VL53L1X(i2c1)
+
+
+def stop():
+    motor_A1.duty_cycle = 0
+    motor_A2.duty_cycle = 0
+    motor_B1.duty_cycle = 0
+    motor_B2.duty_cycle = 0
+
+
+def set_speed(motor, speed):
+    # Swap motor pins if we reverse the speed
+    if speed < 0:
+        direction = motor[1], motor[0]
+        speed = -speed
+    else:
+        direction = motor
+    speed = min(speed, 1)  # limit to 1.0
+    max_speed = 2 ** 16 - 1
+
+    direction[0].duty_cycle = int(max_speed * speed)
+    direction[1].duty_cycle = 0
+
+
+def set_left(speed):
+    set_speed(left_motor, speed)
+
+
+def set_right(speed):
+    set_speed(right_motor, speed)