BakeBit - Rotary Angle Sensor

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1 Introduction

Rotary Angle Senso

• The BakeBit - Rotary Angle Sensor module is a rotary sensor module. It acts as a variable resistor or rheostat.When the nub is rotated the resistance will change.

2 Hardware Spec

• Standard 2.0mm pitch 4-Pin BakeBit Interface

• Pin Description:

Pin	Description
GND	Ground
5V	5V Supply Voltage
NC	Not Connected
SIG	Signal

3 Code Sample(1): LED Fade

A BakeBit - Rotary Angle Sensor module is needed in this test case.

3.1 Hardware Connection

Connect the LED module to the NEO-Hub at D5 and the BakeBit - Rotary Angle Sensor module to the NEO-Hub at A0:

3.2 Source Code

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")

Github

3.3 Run Code Sample

Before you run the code sample you need to follow the steps in bakebit tutorial to intall the BakeBit package.
Enter the "BakeBit/Software/Python" directory and run the "bakebit_rotary_angle_sensor.py" program:

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

3.4 Observation

When you rotate the rotary angle sensor module the LED’s luminance will change accordingly.

4 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。
该示例是配合BakeBit - Servo来实现的，可参考BakeBit - Servo页面。

5 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。
该示例是配合BakeBit - LED Bar来实现的，可参考BakeBit - LED Bar页面。

6 相关资料

• [Schematic](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)