BakeBit - Ultrasonic Ranger

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1 Introduction

Ultrasonic Ranger

• The BakeBit - Ultrasonic Ranger is a ultrasonic module.The module's sensor emits a sound wave whose wave length is around 6mm and frequency is 40K Hz, which bounces off a reflective surface and returns to the sensor. Then, using the amount of time it takes for the wave to return to the sensor, the distance to the object can be computed.The receiver converts ultrasound waves to electrical signals in mV.
• The master sends a signal to the module starting to emit a sound wave. After the module receives the returned signal it will will generate a high level indicating the elapsed time and the distance will be calculated by distance = (elapsed time * speed of sound)/2.

2 Hardware Spec

• Standard 2.0mm pitch 4-Pin BakeBit Interface
• Range: 5cm - 300cm
• Accuracy: 1cm
• PCB dimension(mm): 24 x 42

• Pin Desription:

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

3 Code Sample:Ultrasonic Sensor with LED

This code sample shows how to use the ultrasonic sensor module to measure a distance. When the module detects an object in front of itself the LED will be turned on.

3.1 Hardware Connection

Connect the LED module to the NEO-Hub at D3 and the ultrasonic sensor module to the NEO-Hub at D4:

3.2 Source Code

import bakebit
import time
 
# Connect the BakeBit Ultrasonic Ranger to digital port D4
# SIG,NC,VCC,GND
ultrasonic_ranger = 4
 
# Connect the BakeBit LED to digital port D3
led = 3                                                                      
 
bakebit.pinMode(led,"OUTPUT")
light = 0
 
while True:
    try:
        # Read distance value from Ultrasonic
	distance = bakebit.ultrasonicRead(ultrasonic_ranger)
        print(distance)
	if distance > 0:
		if distance<10: 
			if light == 0:
				print("\ton")
				bakebit.digitalWrite(led,1)
				light = 1
		else:
			if light == 1:
				print("\toff")
				bakebit.digitalWrite(led,0)
				light = 0
	time.sleep(.2)
 
    except KeyboardInterrupt:
	bakebit.digitalWrite(led,0)
        break
 
    except TypeError:
        print ("Error")
    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 install the BakeBit package.
Enter the "BakeBit/Software/Python" directory and run the "bakebit_prj_Ultrasonic_Sensor_with_LED.py" program:

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

3.4 Observation

When an object is in front of the sensor module within 10 cm the LED will be turned on otherwise the LED will be off.

4 相关资料

• [Schematic](BakeBit - Ultrasonic Ranger.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)