Difference between revisions of "BakeBit - Light Sensor/zh"
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==相关资料== | ==相关资料== | ||
*[Schematic]([http://wiki.friendlyarm.com/wiki/images/e/e8/06-SCHEMATIC_Light_Sensor.pdf BakeBit - Light Sensor.pdf]) | *[Schematic]([http://wiki.friendlyarm.com/wiki/images/e/e8/06-SCHEMATIC_Light_Sensor.pdf BakeBit - Light Sensor.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) | ||
Revision as of 08:55, 28 November 2016
1 介绍
- BakeBit - Light Sensor是一个光敏电阻模块，主要器件是一个光敏电阻。光敏电阻的制作材料具有在特定波长的光照射下，其阻值迅速减小的特性。
- 这是由于光照产生的载流子都参与导电，在外加电场的作用下作漂移运动，电子奔向电源的正极，空穴奔向电源的负极，从而使光敏电阻器的阻值迅速下降。在电源激励下，输出端分压减小。
2 特性
- 使用标准的2.0mm 4 Pin BakeBit接口
- PCB尺寸（mm）：20x24
- 模拟信号输出
- 引脚说明:
| 名称 | 描述 |
| GND | 地 |
| 5V | 电源5V |
| NC | 空 |
| SIG | 信号 |
3 示例程序：Smart Lighting
利用亮度传感器，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。 本示例需要配合BakeBit - LED Bar使用。
3.1 硬件连接
简单的将BakeBit - LED Bar模块插入 D3 接口，将BakeBit - Light Sensor插入 A0 接口，如下面这样：
3.2 示例源代码
import time import bakebit # Connect the BakeBit Light Sensor to analog port A0 # SIG,NC,VCC,GND light_sensor = 0 # Connect the BakeBit LED Bar to digital port D3 # DI,DCKI,VCC,GND ledbar = 3 lowThreshold = 500 highTreshold = 600 bakebit.pinMode(light_sensor,"INPUT") bakebit.pinMode(ledbar,"OUTPUT") time.sleep(.2) bakebit.bakeBitLedBar_Init(ledbar, 0, 5) time.sleep(.5) old_color = 0 while True: try: light_count = 0 # Get sensor value sensor_value = bakebit.analogRead(light_sensor) if sensor_value > highTreshold: f=(1023-highTreshold)/4 light_count = (sensor_value-highTreshold)/f+1 # turn on ledbar color16bit = bakebit.Green if light_count > 1: color16bit = color16bit | (bakebit.Green << 3) if light_count > 2: color16bit = color16bit | (bakebit.Green << 6) if light_count > 3: color16bit = color16bit | (bakebit.Green << 9) if light_count > 4: color16bit = 0 color16bit = color16bit | bakebit.Blue color16bit = color16bit | (bakebit.Blue << 3) color16bit = color16bit | (bakebit.Blue << 6) color16bit = color16bit | (bakebit.Blue << 9) color16bit = color16bit | (bakebit.Blue << 12) if color16bit != old_color: old_color = color16bit lowBits = color16bit & 255 highBits = (color16bit & (255 << 8)) >> 8 bakebit.bakeBitLedBar_Show(ledbar, highBits, lowBits) elif sensor_value < lowThreshold: # turn off ledbar bakebit.bakeBitLedBar_Show(ledbar, 0, 0) print("sensor_value = %d light_count =%d" %(sensor_value, light_count)) time.sleep(.5) except KeyboardInterrupt: bakebit.bakeBitLedBar_Release(ledbar) time.sleep(.2) break except IOError: print ("Error")
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_SmartLighting.py:
cd ~/BakeBit/Software/Python sudo python bakebit_prj_SmartLighting.py
3.4 运行结果
测试时可用物品盖住光敏电阻模拟环境变暗，或者用手机电筒照射模拟环境变亮，然后观察LED Bar的变化。
LED Bar上被点亮的LED个数由当前环境的光线决定，越暗，被点亮的就最多。
4 相关资料
- [Schematic](BakeBit - Light Sensor.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)
