examples: line_follower.py and minor mods

Author: eigen-value

examples/line_follower.py

@@ -0,0 +1,60 @@
+from arduino_alvik import ArduinoAlvik
+from time import sleep_ms
+import sys
+
+
+def calculate_center(left: int, center: int, right: int):
+    centroid = 0
+    sum_weight = left + center + right
+    sum_values = left + 2*center + 3*right
+    if sum_weight != 0:
+        centroid = sum_values/sum_weight
+        centroid = 2 - centroid
+    return centroid
+
+
+alvik = ArduinoAlvik()
+alvik.begin()
+
+error = 0
+control = 0
+kp = 50.0
+
+alvik.left_led.set_color(0, 0, 1)
+alvik.right_led.set_color(0, 0, 1)
+
+while not alvik.get_touch_up():
+    sleep_ms(50)
+
+try:
+    while not alvik.get_touch_cancel():
+
+        line_sensors = alvik.get_line_sensors()
+        print(f' {line_sensors}')
+
+        error = calculate_center(*line_sensors)
+        control = error * kp
+
+        if control > 0.2:
+            alvik.left_led.set_color(1, 0, 0)
+            alvik.right_led.set_color(0, 0, 0)
+        elif control < -0.2:
+            alvik.left_led.set_color(1, 0, 0)
+            alvik.right_led.set_color(0, 0, 0)
+        else:
+            alvik.left_led.set_color(0, 1, 0)
+            alvik.right_led.set_color(0, 1, 0)
+
+        alvik.set_wheels_speed(30-control, 30+control)
+        sleep_ms(100)
+
+    while not alvik.get_touch_ok():
+        alvik.left_led.set_color(0, 0, 1)
+        alvik.right_led.set_color(0, 0, 1)
+        alvik.brake()
+        sleep_ms(100)
+
+except KeyboardInterrupt as e:
+    print('over')
+    alvik.stop()
+    sys.exit()

examples/message_reader.py

@@ -3,8 +3,7 @@
 import sys
 
 alvik = ArduinoAlvik()
-if alvik.begin() < 0:
-    sys.exit()
+alvik.begin()
 
 speed = 0