MicroPython實例之TPYBoard v102炫彩跑馬燈WS2812B

ID:130183 · 發表于 2018-6-11 15:32

一、實驗目的

了解ws2812b的工作原理
學習ws2812b的驅動方法

二、實驗器材

TPYBoard v102 1塊
ws2812b RGB-Ring-8 1個
micro USB數據線 1條
杜邦線若干

三、WS2812B的介紹

WS2812B是一個集控制電路與發光電路于一體的智能外控LED光源。其外型與一個5050LED燈珠相同，每個元件即為一個像素點。像素點內部包含了智能數字接口數據鎖存信號整形放大驅動電路，還包含有高精度的內部振蕩器和可編程定電流控制部分，有效保證了像素點光的顏色高度一致。

數據協議采用單線歸零碼的通訊方式，像素點在上電復位以后， DIN端接受從控制器傳輸過來的數據，首先送過來的24bit數據被第一個像素點提取后，送到像素點內部的數據鎖存器，剩余的數據經過內部整形處理電路整形放大后通過DO端口開始轉發輸出給下一個級聯的像素點，每經過一個像素點的傳輸，信號減少24bit。像素點采用自動整形轉發技術，使得該像素點的級聯個數不受信號傳送的限制，僅僅受限信號傳輸速度要求。

實物圖

上圖是8個燈珠的。
WS2812B的引腳說明：

硬件連接
將TPYBoard v102與WS2812B的接線示意圖，如下：

程序源碼如下：

import pyb
import math
from ws2812 import WS2812
ring = WS2812(spi_bus=1, led_count=8, intensity=0.1)
def data_generator(led_count):
data = [(0, 0, 0) for i in range(led_count)]
step = 0
while True:
red = int((1 + math.sin(step * 0.1324)) * 127)
green = int((1 + math.sin(step * 0.1654)) * 127)
blue = int((1 + math.sin(step * 0.1)) * 127)
data[step % led_count] = (red, green, blue)
yield data
step += 1
for data in data_generator(ring.led_count):
ring.show(data)
pyb.delay(100)

復制代碼

里面還需要引入一個ws2812.py 文件。內容如下：

import gc
import pyb
class WS2812:
"""
Driver for WS2812 RGB LEDs. May be used for controlling single LED or chain
of LEDs.
Example of use:
chain = WS2812(spi_bus=1, led_count=4)
data = [
(255, 0, 0), # red
(0, 255, 0), # green
(0, 0, 255), # blue
(85, 85, 85), # white
]
chain.show(data)
Version: 1.0
"""
buf_bytes = (0x11, 0x13, 0x31, 0x33)
def __init__(self, spi_bus=1, led_count=1, intensity=1):
"""
Params:
* spi_bus = SPI bus ID (1 or 2)
* led_count = count of LEDs
* intensity = light intensity (float up to 1)
"""
self.led_count = led_count
self.intensity = intensity
# prepare SPI data buffer (4 bytes for each color)
self.buf_length = self.led_count * 3 * 4
self.buf = bytearray(self.buf_length)
# SPI init
self.spi = pyb.SPI(spi_bus, pyb.SPI.MASTER, baudrate=3200000, polarity=0, phase=1)
# turn LEDs off
self.show([])
def show(self, data):
"""
Show RGB data on LEDs. Expected data = [(R, G, B), ...] where R, G and B
are intensities of colors in range from 0 to 255. One RGB tuple for each
LED. Count of tuples may be less than count of connected LEDs.
"""
self.fill_buf(data)
self.send_buf()
def send_buf(self):
"""
Send buffer over SPI.
"""
self.spi.send(self.buf)
gc.collect()
def update_buf(self, data, start=0):
"""
Fill a part of the buffer with RGB data.
Order of colors in buffer is changed from RGB to GRB because WS2812 LED
has GRB order of colors. Each color is represented by 4 bytes in buffer
(1 byte for each 2 bits).
Returns the index of the first unfilled LED
Note: If you find this function ugly, it's because speed optimisations
beated purity of code.
"""
buf = self.buf
buf_bytes = self.buf_bytes
intensity = self.intensity
mask = 0x03
index = start * 12
for red, green, blue in data:
red = int(red * intensity)
green = int(green * intensity)
blue = int(blue * intensity)
buf[index] = buf_bytes[green >> 6 & mask]
buf[index+1] = buf_bytes[green >> 4 & mask]
buf[index+2] = buf_bytes[green >> 2 & mask]
buf[index+3] = buf_bytes[green & mask]
buf[index+4] = buf_bytes[red >> 6 & mask]
buf[index+5] = buf_bytes[red >> 4 & mask]
buf[index+6] = buf_bytes[red >> 2 & mask]
buf[index+7] = buf_bytes[red & mask]
buf[index+8] = buf_bytes[blue >> 6 & mask]
buf[index+9] = buf_bytes[blue >> 4 & mask]
buf[index+10] = buf_bytes[blue >> 2 & mask]
buf[index+11] = buf_bytes[blue & mask]
index += 12
return index // 12
def fill_buf(self, data):
"""
Fill buffer with RGB data.
All LEDs after the data are turned off.
"""
end = self.update_buf(data)
# turn off the rest of the LEDs
buf = self.buf
off = self.buf_bytes[0]
for index in range(end * 12, self.buf_length):
buf[index] = off
index += 1

復制代碼

本次參考的github上的一個項目。項目地址：
https://github.com/JanBednarik/micropython-ws2812
給大家看一下效果（額最后一個燈珠壞了大家可以自行忽略……）
https://v.qq.com/x/page/d05297wxo1b.html

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MicroPython實例之TPYBoard v102炫彩跑馬燈WS2812B