BakeBit - Servo

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1 Introduction

  • The BakeBit - Servo is a servo module which contains a DC motor and a transmission system.
  • Its input signal is PWM. The motor's steering angle changes according to PWM signals' changes. The input PWM's frequency is 50Hz and its width is 0.5ms—2.5ms. The motor's steering angle is 0 - 180°.
  • A PWM input steers the motor to an angle. When no input signals are applied the motor will stop.

2 Hardware Spec

  • Standard 2.0mm pitch 4-Pin BakeBit Interface

Servo's dimension

BakeBit - Servo

  • Spec:

BakeBit - Servo detail

  • Pin Description:
Pin Name Description
1 SIG Signal
2 NC Not Connected
3 5V 5V Supply Voltage
4 GND Ground

3 Code Sample: Servo and Rotary Angle Sensor

By running this code sample users can control a servo with the BakeBit - Rotary Angle Sensor module. The servo's streering angle is between 0~180 degrees.

3.1 Hardware Setup

Connect the servo module to the NanoHat Hub's D5 and the rotary angle sensor module to the NanoHat Hub's A0:

Servo and Rotary Angle Sensor-1.jpg Servo and Rotary Angle Sensor-2.jpg

3.2 Source Code

import time
import bakebit
import random
# Connect the servo to digital port D5
servo = 5
# Connect the BakeBit Rotary Angle Sensor to analog port A0
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
while True:
        # 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:
    except IOError:
        print ("Error")


3.3 Run Code Sample

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

cd ~/BakeBit/Software/Python
sudo python

3.4 Observation

When you rotate the rotary angle module the servo will be steered between 0 to 180 degrees.

4 Resources

5 Update Log

5.1 December-14-2016

  • Released English Version

5.2 Jan-19-2017

  • Renamed "NEO-Hub" to "NanoHat-Hub"

5.3 Jan-20-2017

  • Renamed "NanoHat-Hub" to "NanoHat Hub"