BakeBit - Servo/zh

English

1 介绍

Servo

• BakeBit - Servo是一个舵机模块，内部包含一个直流电机和齿轮传动反馈系统。用于机器人等机械结构的驱动和控制。
• 舵机的转动和转角都是跟随着信号脉冲的宽度变化而变化的,控制信号为频率50Hz的PWM信号，该控制信号高电平部分范围为0.5ms—2.5ms，对应的舵机旋转角度为0-180°。
• 给舵机一个PWM信号，舵机便会旋转到对应的角度。信号停止在一个脉冲宽度时舵机也就不转了，停在对应的角度上.

2 特性

• 使用标准的2.0mm 4 Pin BakeBit接口

舵机规格尺寸如下：

• 规格参数如下：

• 引脚说明:

引脚	名称	描述
1	SIG	信号
2	NC	空
3	5V	电源5V
4	GND	地

3 示例程序：Servo and Rotary Angle Sensor

这个示例演示用BakeBit - Rotary Angle Sensor来控制舵机的转动, 随着你转动电位器，舵机将在0～180角范围里旋转。

3.1 硬件连接

简单的将 舵机 模块插入D5接口，将电位器模块插入A0接口，如下面这样：

3.2 示例源代码

import time
import bakebit
import random
 
# Connect the servo to digital port D5
# SIG,NC,VCC,GND
servo = 5
 
# 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 180 degrees, as per it's specs (0 to 180)
full_angle = 180
old_degrees = -1
 
bakebit.pinMode(potentiometer,"INPUT")
bakebit.bakeBitServo_Attach(servo)
 
 
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 180)
        degrees = int((voltage * full_angle) / bakebit_vcc)
 
        if degrees != old_degrees:
            print("sensor_value = %d voltage = %.2f degrees = %d" % (sensor_value, voltage, degrees))
            bakebit.bakeBitServo_Write(servo, degrees)
 
        old_degrees = degrees
 
    except KeyboardInterrupt:
        bakebit.bakeBitServo_Detach(servo)
        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_Servo_And_RotaryAngleSensor.py:

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

3.4 运行结果

随着你转动电位器，舵机将在0～180角范围里旋转。

4 相关资料

• [Specification](BakeBit - Servo Specification.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)