BakeBit - LED Bar

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1 介绍

LED Bar

• BakeBit - LED-Bar是一个多彩led模块，模块使用了五个内部集成了Ws2812控制芯片的多彩LED，每个LED内部有R、G、B三个发光二极管。Ws2812控制芯片串行读取控制信号，并从中提取出RGB颜色分量，再分别控制R、G、B发光二极管的亮度，混色出不同的色彩。每个像素点的三基色颜色可实现256级亮度显示，总共完成16777216种颜色的全真色彩显示。
• 五个LED串行级联，只需要串行的写入控制信号，五个LED便会发出缤纷斑斓的色彩。

2 特性

• 使用标准的2.0mm 4 Pin BakeBit接口
• 多彩R、G、B LED
• 全真色彩显示

• 引脚说明:

名称	描述
GND	地
5V	电源5V
NC	空
SIG	信号

3 示例程序(1)：LED Bar

这个项目实现类拟音量调节的效果，用到电位器模块和LED Bar。
本示例需要配合BakeBit - Rotary Angle Sensor使用。

3.1 硬件连接

简单的将 LED Bar 模块插入 D3 接口，将 电位器 插入 A0 接口，如下面这样：

3.2 示例源代码

import time
import bakebit
import random
 
# Connect the BakeBit LED Bar to digital port D3
# DI,DCKI,VCC,GND
ledbar = 3
 
# Connect the BakeBit Rotary Angle Sensor to analog port A0
# SIG,NC,VCC,GND
potentiometer = 0
 
# Reference voltage of ADC is 5v
adc_ref = 5
 
# Vcc of the bakebit interface is normally 5v
bakebit_vcc = 5
 
# Full value of the rotary angle is 360 degrees, as per it's specs (0 to 360)
full_angle = 360
 
bakebit.pinMode(potentiometer,"INPUT")
bakebit.pinMode(ledbar,"OUTPUT")
time.sleep(1)
 
# LED Bar methods
# bakebit.bakeBitLedBar_Init(pin, chipset, numOfLED)
# bakebit.bakeBitLedBar_Release(pin)
# bakebit.bakeBitLedBar_Show(pin,colorHigh,colorLow)
 
bakebit.bakeBitLedBar_Init(ledbar, 0, 5)
time.sleep(.5)
 
old_color = 0
while True:
    try:
        # Read sensor value from potentiometer
        sensor_value = bakebit.analogRead(potentiometer)
 
        # Calculate voltage
        voltage = round((float)(sensor_value) * adc_ref / 1023, 2)
 
        # Calculate rotation in degrees (0 to 360)
        degrees = round((voltage * full_angle) / bakebit_vcc, 2)
        print("sensor_value = %d voltage = %.2f degrees = %.1f" % (sensor_value, voltage, degrees))
 
        color16bit = 0
        if degrees > 0:
            color16bit = color16bit | bakebit.Green
        if degrees > 72:
            color16bit = color16bit | (bakebit.Green<<3)
        if degrees > 144:
            color16bit = color16bit | (bakebit.Green << 6)
        if degrees > 216:
            color16bit = color16bit | (bakebit.Yellow << 9)
        if degrees > 288:
            color16bit = color16bit | (bakebit.Red << 12)
        if degrees == 360:
            color16bit = 0
            color16bit = color16bit | bakebit.Red
            color16bit = color16bit | (bakebit.Red << 3)
            color16bit = color16bit | (bakebit.Red << 6)
            color16bit = color16bit | (bakebit.Red << 9)
            color16bit = color16bit | (bakebit.Red << 12)
 
        if color16bit == old_color:
            continue
        old_color = color16bit
 
        lowBits = color16bit & 255
        highBits = (color16bit & (255<<8))>>8
        print("%s %s" % ('{0:08b}'.format(highBits), '{0:08b}'.format(lowBits)))
        bakebit.bakeBitLedBar_Show(ledbar, highBits, lowBits)
        time.sleep(.2)
 
    except KeyboardInterrupt:
        bakebit.bakeBitLedBar_Release(ledbar)
        time.sleep(.2)
        break
    except IOError:
        print ("Error")

Github

3.3 运行示例

假设你已经参考bakebit教程安装了BakeBit源代码，
要运行示例程序，可以在开发板上进入 BakeBit/Software/Python目录,运行bakebit_prj_LEDBar_And_RotaryAngleSensor.py:

cd ~/BakeBit/Software/Python
sudo python bakebit_prj_LEDBar_And_RotaryAngleSensor.py

3.4 运行结果

旋转电位器，LED Bar上被点亮的LED个数将根据你的操作角度而进行变化。

4 示例程序(2)：Smart Lighting

该示例利用BakeBit - Light Sensor亮度传感器，聪明地控制灯光(灯用LED Bar来模拟)，环境越暗就让灯越亮，环境亮度足够时，就将灯变暗或者熄灭。
该示例是配合BakeBit - Light Sensor来实现的，可参考BakeBit - Light Sensor页面。

5 相关资料

• [Schematic](BakeBit - LED Bar.pdf)
• [BakeBit Github项目](https://github.com/friendlyarm/BakeBit)
• [BakeBit Starter Kit手册](http://wiki.friendlyarm.com/bakebit/bakebit_starter_kit_manual_cn.pdf)