diff --git a/ch-11/1-measuring_wheel_speeds/code.py b/ch-11/1-measuring_wheel_speeds/code.py
index 35f44f4..ae922cd 100644
--- a/ch-11/1-measuring_wheel_speeds/code.py
+++ b/ch-11/1-measuring_wheel_speeds/code.py
@@ -28,7 +28,7 @@ async def command_handler():
     if uart.in_waiting:
       command = uart.readline().decode().strip()
       if command.startswith("M"):
-        speed = float(command[1:])
+        Settings.speed = float(command[1:])
       elif command.startswith("T"):
         Settings.time_interval = float(command[1:])
       elif command == "O":
@@ -43,5 +43,8 @@ async def command_handler():
         await asyncio.sleep(3)
     await asyncio.sleep(0)
 
-asyncio.create_task(motor_speed_loop())
-asyncio.run(command_handler())
+try:
+  asyncio.create_task(motor_speed_loop())
+  asyncio.run(command_handler())
+finally:
+  robot.stop()
diff --git a/ch-11/1-measuring_wheel_speeds/pio_encoder.py b/ch-11/1-measuring_wheel_speeds/pio_encoder.py
index ffcc9f2..b831bf4 100644
--- a/ch-11/1-measuring_wheel_speeds/pio_encoder.py
+++ b/ch-11/1-measuring_wheel_speeds/pio_encoder.py
@@ -1,6 +1,8 @@
 import rp2pio
 import adafruit_pioasm
 import array
+import asyncio
+
 
 program = """
 ; use the osr for count
@@ -67,10 +69,15 @@ class QuadratureEncoder:
         )
         self.reversed = reversed
         self._buffer = array.array("i", [0])
+        asyncio.create_task(self.poll_loop())
+
+    async def poll_loop(self):
+        while True:
+            await asyncio.sleep(0)
+            while self.sm.in_waiting:
+                self.sm.readinto(self._buffer)
 
     def read(self):
-        while self.sm.in_waiting:
-            self.sm.readinto(self._buffer)
         if self.reversed:
             return -self._buffer[0]
         else:
diff --git a/ch-11/1-measuring_wheel_speeds/robot.py b/ch-11/1-measuring_wheel_speeds/robot.py
index 4efeb56..70ebaef 100755
--- a/ch-11/1-measuring_wheel_speeds/robot.py
+++ b/ch-11/1-measuring_wheel_speeds/robot.py
@@ -7,22 +7,24 @@ import math
 
 wheel_diameter_mm = 70
 wheel_circumference_mm = math.pi * wheel_diameter_mm
-ticks_per_revolution = 2800
+gear_ratio = 298
+encoder_poles = 28
+ticks_per_revolution = encoder_poles * gear_ratio
 ticks_to_mm_const = wheel_circumference_mm / ticks_per_revolution
 
 def ticks_to_mm(ticks):
     return ticks_to_mm_const * ticks
 
-motor_A1 = pwmio.PWMOut(board.GP17, frequency=100)
-motor_A2 = pwmio.PWMOut(board.GP16, frequency=100)
-motor_B1 = pwmio.PWMOut(board.GP18, frequency=100)
-motor_B2 = pwmio.PWMOut(board.GP19, frequency=100)
+motor_A2 = pwmio.PWMOut(board.GP17, frequency=100)
+motor_A1 = pwmio.PWMOut(board.GP16, frequency=100)
+motor_B2 = pwmio.PWMOut(board.GP18, frequency=100)
+motor_B1 = pwmio.PWMOut(board.GP19, frequency=100)
 
 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)
+right_encoder = pio_encoder.QuadratureEncoder(board.GP20, board.GP21)
+left_encoder = pio_encoder.QuadratureEncoder(board.GP26, board.GP27, reversed=True)
 
 i2c0 = busio.I2C(sda=board.GP0, scl=board.GP1)
 i2c1 = busio.I2C(sda=board.GP2, scl=board.GP3)