Case 11: Rainbow LED
13. Case 11: Rainbow LED#
The Rainbow LED is based on the ws2812b bead. Its obvious feature is the single IO control with infinite cascade. In this lesson, we will use Pico:ed to drive the it to achieve a colourful effect.
13.2. Components List#
1 × Pico:ed
1 × USB Cable
1 × Breadboard Adapter
1 × 83×55mm Breadboard
1× Rainbow LED
N* Dupont Cables
13.3. Main Components#
8 RGB Rainbow LED Ring is an LED ring made of 8 ws2812b beads in cascade connection. Ws2812b is an intelligent outer control LED source, which has integrated control circuit and light emitting circuit. It has same appearance with 5050LED bead.
The digital protocol adopts communication method of single line goes to zero. After pixel point restoration, DIN will receive the data sent from the controller. Once the first 24-bit data received was extracted by the first pixel point, it will be sent to the internal digital lock storage device of pixel point and the rest data amplified through the inner transformation processing circuit will be sent to the next pixel point from DO port. Every time it passes through a pixel point transmission, the signal will decrease 24bit. The pixel point uses automatic transformation forwarding technique, thus the pixel cascade connection quantity do not limited by signal transmission but the speed of transmission only.
LED has advantages of low voltage drive, energy-saving and environment protect, wide scattering angle, good consistency, ultra-long life, etc.. To integrate control circuit onto LED, the circuit will become more simple, easier to install and have smaller volume.
Connect the components as the pictures suggest:
1.Connect the signal wire of the rainbow LED to the P0 port of the expansion board
Note: The light leads to two sets of wires, one for DI, the other for DO, and here we should connect the DI.
This is the picture after finishing the connections:
Program Preparation: Prpgramming environment
# Import the modules that we need: import board import random import neopixel_write import digitalio import time # Set the pins and directions of the Rainbow LED pin = digitalio.DigitalInOut(board.P0_A0) pin.direction = digitalio.Direction.OUTPUT # Initialize the list to save the value of the RGB rings = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0] # While true, loop the RGB value for each bead while True: for i in range(len(rings)): rings[i] = random.randint(0,255) pixel_off = bytearray(rings) neopixel_write.neopixel_write(pin, pixel_off) time.sleep(0.1)
Details of the Code:#
Import the modules that we need.
boardis the common container, and you can connect the pins you’d like to use through it. the
digitaliomodule contains classes that provide access to basic digital IO. The
timemodule contains functions for setting the time, the
randommodule contains functions that provide for creating random numbers and the
neopixel_writemodule contains a helper method for writing out bytes in the 800khz neopixel protocol.
import board import random import neopixel_write import digitalio import time
Set the pins and directions of the Rainbow LED
pin = digitalio.DigitalInOut(board.P0_A0) pin.direction = digitalio.Direction.OUTPUT
If the pins you are using are not P0_A0 and P1_A1, the other pin numbers can be viewed by entering the following code in the shell window below the Thonny editor.
>>> import board >>> help(board) object <module 'board'> is of type module __name__ -- board board_id -- elecfreaks_picoed BUZZER_GP0 -- board.BUZZER_GP0 I2C0_SDA -- board.BUZZER_GP0 I2C0_SCL -- board.I2C0_SCL BUZZER -- board.BUZZER BUZZER_GP3 -- board.BUZZER P4 -- board.P4 P5 -- board.P5 P6 -- board.P6 P7 -- board.P7 P8 -- board.P8 P9 -- board.P9 P10 -- board.P10 P11 -- board.P11 P12 -- board.P12 P13 -- board.P13 P14 -- board.P14 P15 -- board.P15 P16 -- board.P16 SDA -- board.SDA P20 -- board.SDA SCL -- board.SCL P19 -- board.SCL BUTTON_A -- board.BUTTON_A BUTTON_B -- board.BUTTON_B SMPS_MODE -- board.SMPS_MODE VBUS_SENSE -- board.VBUS_SENSE LED -- board.LED P0_A0 -- board.P0_A0 P0 -- board.P0_A0 A0 -- board.P0_A0 P1_A1 -- board.P1_A1 P1 -- board.P1_A1 A1 -- board.P1_A1 P2_A2 -- board.P2_A2 P2 -- board.P2_A2 A2 -- board.P2_A2 P3_A3 -- board.P3_A3 P3 -- board.P3_A3 A3 -- board.P3_A3
Initialize the list to save the value of the RGB
rings = [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]
While true, loop the RGB value for each bead
while True: for i in range(len(rings)): rings[i] = random.randint(0,255) pixel_off = bytearray(rings) neopixel_write.neopixel_write(pin, pixel_off) time.sleep(0.1)
The Rainbow LED lights on in a colorful way.
How to make a blink rainbow LED just like a blinking eye?