• ws2812的控制
• Github上的资源整理

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.

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 #13 is given below:

import array, time from machine import Pin import rp2

ledcount = 16 # number of LEDs in ring light PINNUM = 13 # pin connected to ring light brightness = 0.5 # 0.1 = darker, 1.0 = brightest

@rp2.asmpio(sidesetinit=rp2.PIO.OUTLOW, outshiftdir=rp2.PIO.SHIFTLEFT, autopull=True, pullthresh=24) # PIO configuration

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()

statemach = rp2.StateMachine(0, ws2812, freq=8000000, sidesetbase=Pin(PIN_NUM))

state_mach.active(1) The snippet of code given above will be used for each algorithm used to test the 16-pixel WS2812 LED ring light.

# 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)