## WS2812B RGB三色灯的控制

  - [[https://makersportal.com/blog/ws2812-ring-light-with-raspberry-pi-pico|ws2812的控制]]
  - [[https://github.com/makerportal/rpi-pico-ws2812|Github上的资源整理]]
{{ :ws2812timing.png |}}


### WS2812B教程内容
[[mp_ws2812b|]]


### 1. 连线图
The wiring diagram between the Raspberry Pi Pico and a 16-pixel RGB LED ring light is shown below:

Wiring Diagram

The pinout wiring is also given in the table below:

Power Supply	Pico	Ring Light
+	N/A	5V
N/A	GPIO13	DI
-	GND	GND
Most of the GPIO pins can be used to control the WS2812 LED array, thus, the specification of GPIO13 for controlling the light is arbitrary. Be sure to change the pin in the codes as well, if using another pin for wiring.
{{::WS2812_Pin.png|}}

### 2. ws2812的使用示例
The 16-Pixel RGB LED ring light array will be controlled using the scheme outlined in the Raspberry Pi Pico MicroPython getting started document, where we can get started with the tutorial entitled “Using PIO to drive a set of NeoPixel Ring (WS2812 LEDs).” The tutorial contains a script that will be used to create a state machine on the RPi Pico. The state machine will be used to control the LEDs on the ring light using a single pin on the Pico (GPIO13 in the wiring above). The full MicroPython example script can also be found at the Raspberry Pi Pico’s NeoPixel Ring repository.

The code to start the state machine on the Pico's GPIO pin #20 is given below:
<code python>
# Example using PIO to drive a set of WS2812 LEDs.

import array, time
from machine import Pin
import rp2

# Configure the number of WS2812 LEDs.
NUM_LEDS = 16
PIN_NUM = 6
brightness = 0.2

@rp2.asm_pio(sideset_init=rp2.PIO.OUT_LOW, out_shiftdir=rp2.PIO.SHIFT_LEFT, autopull=True, pull_thresh=24)
def ws2812():
    T1 = 2
    T2 = 5
    T3 = 3
    wrap_target()
    label("bitloop")
    out(x, 1)               .side(0)    [T3 - 1]
    jmp(not_x, "do_zero")   .side(1)    [T1 - 1]
    jmp("bitloop")          .side(1)    [T2 - 1]
    label("do_zero")
    nop()                   .side(0)    [T2 - 1]
    wrap()


# Create the StateMachine with the ws2812 program, outputting on pin
sm = rp2.StateMachine(0, ws2812, freq=8_000_000, sideset_base=Pin(PIN_NUM))

# Start the StateMachine, it will wait for data on its FIFO.
sm.active(1)

# Display a pattern on the LEDs via an array of LED RGB values.
ar = array.array("I", [0 for _ in range(NUM_LEDS)])

##########################################################################
def pixels_show():
    dimmer_ar = array.array("I", [0 for _ in range(NUM_LEDS)])
    for i,c in enumerate(ar):
        r = int(((c >> 8) & 0xFF) * brightness)
        g = int(((c >> 16) & 0xFF) * brightness)
        b = int((c & 0xFF) * brightness)
        dimmer_ar[i] = (g<<16) + (r<<8) + b
    sm.put(dimmer_ar, 8)
    time.sleep_ms(10)

def pixels_set(i, color):
    ar[i] = (color[1]<<16) + (color[0]<<8) + color[2]

def pixels_fill(color):
    for i in range(len(ar)):
        pixels_set(i, color)

def color_chase(color, wait):
    for i in range(NUM_LEDS):
        pixels_set(i, color)
        time.sleep(wait)
        pixels_show()
    time.sleep(0.2)
 
def wheel(pos):
    # Input a value 0 to 255 to get a color value.
    # The colours are a transition r - g - b - back to r.
    if pos < 0 or pos > 255:
        return (0, 0, 0)
    if pos < 85:
        return (255 - pos * 3, pos * 3, 0)
    if pos < 170:
        pos -= 85
        return (0, 255 - pos * 3, pos * 3)
    pos -= 170
    return (pos * 3, 0, 255 - pos * 3)
 
 
def rainbow_cycle(wait):
    for j in range(255):
        for i in range(NUM_LEDS):
            rc_index = (i * 256 // NUM_LEDS) + j
            pixels_set(i, wheel(rc_index & 255))
        pixels_show()
        time.sleep(wait)

BLACK = (0, 0, 0)
RED = (255, 0, 0)
YELLOW = (255, 150, 0)
GREEN = (0, 255, 0)
CYAN = (0, 255, 255)
BLUE = (0, 0, 255)
PURPLE = (180, 0, 255)
WHITE = (255, 255, 255)
COLORS = (BLACK, RED, YELLOW, GREEN, CYAN, BLUE, PURPLE, WHITE)

print("fills")
for color in COLORS:       
    pixels_fill(color)
    pixels_show()
    time.sleep(0.2)

print("chases")
for color in COLORS:       
    color_chase(color, 0.01)

print("rainbow")
rainbow_cycle(0)
</code>