View source for BakeBit - Rotary Angle Sensor/zh

[[BakeBit - Rotary Angle Sensor|English]]
==介绍==
[[File:BakeBit - Rotary Angle Senso.jpg|thumb|Rotary Angle Senso]]
*BakeBit - Rotary Angle Senso是一个旋转角度传感器模块，模块使用了一个旋转电位器。通过改变接入电路部分电阻线的长度来改变接入部分的电阻值，从而改变输出端的分压。

==特性==
* 使用标准的2.0mm 4 Pin BakeBit接口
[[File:BakeBit - Rotary Angle Senso_PCB.png | frameless|320px|BakeBit - Rotary Angle Senso]]

* 引脚说明:
{| class="wikitable"
|-
|名称 || 描述
|-
|GND   || 地
|-
|5V    || 电源5V
|-
|NC    || 空
|-
|SIG   || 信号
|}
== 示例程序(1)：LED Fade ==

这个项目将使用[[BakeBit - Rotary Angle Sensor]]模块，来动态调节LED的亮度。

=== 硬件连接 ===
简单的将 LED 模块插入 D5接口，将 [[BakeBit - Rotary Angle Sensor]] 插入 A0接口，如下面这样：

::{| class="wikitable"
|-
|[[File:LED Fade-1.jpg |frameless|300px]]    || [[File:LED Fade-2.jpg |frameless|300px]] 
|-
|}

=== 示例源代码 ===

<syntaxhighlight lang="python">
import time
import bakebit

# Connect the BakeBit Rotary Angle Sensor to analog port A0
# SIG,NC,VCC,GND
potentiometer = 0

# Connect the LED to digital port D5
# SIG,NC,VCC,GND
led = 5

bakebit.pinMode(potentiometer,"INPUT")
bakebit.pinMode(led,"OUTPUT")
time.sleep(1)

# 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 300 degrees, as per it's specs (0 to 300)
full_angle = 300

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 300)
        degrees = round((voltage * full_angle) / bakebit_vcc, 2)

        # Calculate LED brightess (0 to 255) from degrees (0 to 300)
        brightness = int(degrees / full_angle * 255)

        # Give PWM output to LED
        bakebit.analogWrite(led,brightness)

        print("sensor_value = %d voltage = %.2f degrees = %.1f brightness = %d" %(sensor_value, voltage, degrees, brightness))
    except KeyboardInterrupt:
        bakebit.analogWrite(led,0)
        break
    except IOError:
        print ("Error")
</syntaxhighlight>
[https://github.com/friendlyarm/BakeBit/blob/master/Software/Python/bakebit_rotary_angle_sensor.py Github]

=== 运行示例 ===
 
假设你已经参考[http://wiki.friendlyarm.com/bakebit bakebit教程]安装了BakeBit源代码，<br />
要运行示例程序，可以在开发板上进入 BakeBit/Software/Python目录,运行bakebit_rotary_angle_sensor.py:
<syntaxhighlight lang="bash">
cd ~/BakeBit/Software/Python
sudo python bakebit_rotary_angle_sensor.py
</syntaxhighlight>


=== 运行结果 ===

旋转电位器，LED亮度会随着电位器的角度变化而变化。

== 示例程序(2)：Servo and Rotary Angle Sensor ==
这个示例演示用电位器(Rotary Angle Sensor)来控制舵机的转动。<br />
该示例是配合[[BakeBit - Servo]]来实现的，可参考[[BakeBit - Servo]]页面。

== 示例程序(3)：LED Bar and Rotary Angle Sensor ==
这个示例实现类拟音量调节的效果，用到电位器模块和LED Bar。<br />
该示例是配合[[BakeBit - LED Bar]]来实现的，可参考[[BakeBit - LED Bar]]页面。

==相关资料==
*[Schematic]([http://wiki.friendlyarm.com/wiki/images/0/01/03-SCHEMATIC_Rotary_Angle_Senso.pdf BakeBit - Rotary Angle 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)