4. light.py Module

If we want to add light effects to the car, we will need to change some LEDs separately. In order to add left turn indicator, we must control the LEDs with serial number 6 and 7; if we modify the right bottom RGB Board, we must control the LEDs with serial number 16~23.

When writing code, it is easy to get confused. To make things even easier, we created different functions that could control different RGB boards or LEDs at specific locations. These functions were then wrapped in a new library.

For example, if you want the 2 LEDs on the tail RGB board to be illuminated, use the following command.

set_rear_right_color(0xaa0000)

Note

The encapsulated library lights.py has been saved in pico_4wd_car-v2.0\libs, which may differ from the ones shown in the course, so please refer to the file under libs path when using it.

Now you can copy this code into Thonny and then click the button or press F5 to run it.

When you power up the Pico 4WD car, you will see 3 RGB boards displaying many different color effects.

from ws2812 import WS2812

 LIGHT_PIN = 19
 LIGHT_NUM = 24

 LIGHT_REAR_RIGHT = [0, 1]
 LIGHT_REAR_MIDDLE = [2, 3, 4, 5]
 LIGHT_REAR_LEFT = [6, 7]
 LIGHT_REAR = [0, 1, 2, 3, 4, 5, 6, 7]

 LIGHT_BOTTOM_LEFT = [8, 9, 10, 11, 12, 13, 14, 15]
 LIGHT_BOTTOM_RIGHT = [16, 17, 18, 19, 20, 21, 22, 23]

 np = WS2812(LIGHT_PIN, LIGHT_NUM)

 def set_all_color(color):
     ''' set color to all lights

         color list or hex, 1*3 list, the order is [red, green, blue]
     '''
     for i in range(24):
         np[i] = color
     np.write()

 def set_color_at(num, color):
     if isinstance(num,list):
         for i in num:
             if i > LIGHT_NUM:
                 raise ValueError("num element must be less than LIGHT_NUM.")
             np[i] = color
     elif  type(num) is int:
         if num > LIGHT_NUM:
             raise ValueError("num must be less than LIGHT_NUM.")
         np[num] = color
     else:
         raise ValueError("num must be list or int.")
     np.write()

 def set_bottom_left_color(color):
     for num in LIGHT_BOTTOM_LEFT:
         np[num] = color
     np.write()

 def set_bottom_right_color(color):
     for num in LIGHT_BOTTOM_RIGHT:
         np[num] = color
     np.write()

 def set_bottom_color(color):
     for num in LIGHT_BOTTOM_LEFT:
         np[num] = color
     for num in LIGHT_BOTTOM_RIGHT:
         np[num] = color
     np.write()

 def set_rear_color(color):
     for num in LIGHT_REAR:
         np[num] = color
     np.write()

 def set_rear_right_color(color):
     for num in LIGHT_REAR_RIGHT:
         np[num] = color
     np.write()

 def set_rear_middle_color(color):
     for num in LIGHT_REAR_MIDDLE:
         np[num] = color
     np.write()

 def set_rear_left_color(color):
     for num in LIGHT_REAR_LEFT:
         np[num] = color
     np.write()

 def set_off():
     set_all_color([0, 0, 0])

 # call function

 import time
 set_all_color(0x33aa66)
 time.sleep(0.5)
 set_bottom_color([255,255,100])
 time.sleep(0.5)
 set_bottom_left_color(0x6633ff)
 time.sleep(0.5)
 set_bottom_right_color([255,66,100])
 time.sleep(0.5)
 set_rear_color(0x88aa00)
 time.sleep(0.5)
 set_rear_right_color(0xaa0000)
 time.sleep(0.5)
 set_rear_middle_color(0x00aa00)
 time.sleep(0.5)
 set_rear_left_color(0x0000aa)
 time.sleep(0.5)

 for i in range(8):
     set_off()
     time.sleep(0.01)
     set_color_at(i,0xaa00cc)
     time.sleep(0.3)

 set_off()
 time.sleep(0.1)
 set_color_at([1,3,5,7],0xccaa00)
 time.sleep(0.5)

 set_off()
 time.sleep(0.1)
 set_color_at([0,2,4,6],0x00ccaa)
 time.sleep(0.5)

 set_off()