In this series of lessons you have learned to send data from Arduino to Python, and then do some pretty cool things in Python. We have created little virtual worlds, and have done neat dynamic graphics. Unfortunately not all Python libraries are as easy to install as vPython and pySerial. Some are next to impossible to install. The good news is that there is a free program called PIP that will install just about any Python library very easily. We need to pause and install PIP. Many of the future lessons will require you to have PIP installed on your machine. Please follow along with me on the video, which shows you how to install PIP on your windows machine. These links will be useful. You can download pip at this link:

https://pip.pypa.io/en/latest/installing.html

Go to the section on PIP install as seen here:

Right mouse click on get-pip.py and download to your desktop. You will then want to run the program in python. We show you how to do this in the video above. Then, you need to edit your system path file by going to the control panel, select system, select advanced settings, and under environmental parameters select the path. Update your path file to show your system where your python folder is and where your python script folder is. If you are unsure of this, watch the video where I show you exactly how to do it. If you are adept with computers, you can just do it from this description. Add the two elements to your path. Adjust the parameters to reflect where your python installation is and where your python script folder is. For me, these are the two things added to my path:

C:\Python27

and

C:\Python27\Scripts

If you do not know exactly what I am saying, then watch the video for more detail.

Once you have these in your system path, you can test your PIP as follows.

Open a CMD box.

Type:

pip install -U pip

This asks pip to update itself. You should see it come up and indicate it is either up to date or is updating. This will tell you that you have the PIP installed correctly.

Your life with Python will now be much easier because your system now knows the path to both your Python program and your PIP installer.

Arduino, Arduino with Python

Python with Arduino LESSON 5: Finishing our Virtual Reality Example

July 22, 2014 admin

This Lesson finishes the work that was begun in Python with Arduino LESSON 4. In that lesson we built the circuit and programmed the arduino to measure the distance to a target and the color of the target. The program then output that data to the serial port. In today’s lesson we will use python to read that data stream, and use the data to dynamically update a virtual world we create.

You will need to start with the work in LESSON 4 to get your circuit working, and your arduino programmed up. Once you have done that, you are ready to use Python to program up your virtual world. Remember you will need to have the pyserial and the vPython libraries loaded. We showed how to install the software in Python with Arduino LESSON 2.

In the video we will go through the process step-by-step to create a virtual world. The code we end up with is posted below. You should not copy and paste the code, but just glance at it if you get stuck. In the end, you should develop your own virtual world and just use mine as a guide if you need more help.

## This program reads data over the serial port
## from that arduino. You have to read an entire line of data
## and then you have to parse it into different number values
## Then those R, G, B numbers are used to make the color of
## a visual object in python change.

import serial #import serial library
from visual import * #import vPython library

MyScene=display(title='My Virtual World') #Create your scene and give it a title.

MyScene.width=800  #We can set the dimension of your visual box. 800X800 pixels works well on my screen
MyScene.height= 800
MyScene.autoscale=False #We want to set the range of the scene manually for better control. Turn autoscale off
MyScene.range = (12,12,12) #Set range of your scene to be 12 inches by 12 inches by 12 inches. 
target=box(length=.1, width=10,height=5, pos=(-6,0,0)) #Create the object that will represent your target (which is a colored card for our project)
myBoxEnd=box(length=.1, width=10,height=5, pos=(-8.5,0,0)) #This object is the little square that is the back of the ultrasonic sensor
myTube2=cylinder(color=color.blue, pos=(-8.5,0,-2.5), radius=1.5,length=2.5 ) #One of the 'tubes' in the front of the ultrasonic sensor
myTube3=cylinder(color=color.blue, pos=(-8.5,0,2.5), radius=1.5,length=2.5 )  #Other tube
myBall=sphere(color=color.red, radius=.3)

sensorData= serial.Serial('com11',115200) # Create senorData object to read serial port data coming from arduino

while True: #This is a while loop that will loop forever, since True is always True.
    
    rate(25) #We need to tell Vpython how fast to go through the loop. 25 times a second works pretty well
    while(sensorData.inWaiting()==0): # Wait here untill there is data on the Serial Port
        pass                          # Do nothing, just loop until data arrives
    textline = sensorData.readline()     # read the entire line of text
    dataNums=textline.split(',')       #Remember to split the line of text into an array at the commas
    red=float(dataNums[0])             # Make variables for Red, Blue, Green. Remember
    green=float(dataNums[1])            # the array was read as text, so must be converted
    blue=float(dataNums[2])           # to numbers with float command
    dist=float(dataNums[3])            # last number in the list is the distance

    blue=blue*.7                      #On my sensor, blue is always a little too strong, so I tone it down a little
    if (dist>=1.5 and dist<=2.25):    #only change color or target if target is between 1.5 and 2.25 inches from sensor
        target.color=(red/255., green/255., blue/255.) #This keeps color from flickering.

    target.pos=vector(-6 + dist,0,0)  #Adjust the position of the target object to match the distance of the real target from the real sensor

## This program reads data over the serial port

## from that arduino. You have to read an entire line of data

## and then you have to parse it into different number values

## Then those R, G, B numbers are used to make the color of

## a visual object in python change.

import serial #import serial library

from visual import * #import vPython library

MyScene=display(title='My Virtual World') #Create your scene and give it a title.

MyScene.width=800 #We can set the dimension of your visual box. 800X800 pixels works well on my screen

MyScene.height= 800

MyScene.autoscale=False #We want to set the range of the scene manually for better control. Turn autoscale off

MyScene.range = (12,12,12) #Set range of your scene to be 12 inches by 12 inches by 12 inches.

target=box(length=.1, width=10,height=5, pos=(-6,0,0)) #Create the object that will represent your target (which is a colored card for our project)

myBoxEnd=box(length=.1, width=10,height=5, pos=(-8.5,0,0)) #This object is the little square that is the back of the ultrasonic sensor

myTube2=cylinder(color=color.blue, pos=(-8.5,0,-2.5), radius=1.5,length=2.5 ) #One of the 'tubes' in the front of the ultrasonic sensor

myTube3=cylinder(color=color.blue, pos=(-8.5,0,2.5), radius=1.5,length=2.5 ) #Other tube

myBall=sphere(color=color.red, radius=.3)

sensorData= serial.Serial('com11',115200) # Create senorData object to read serial port data coming from arduino

while True: #This is a while loop that will loop forever, since True is always True.

rate(25) #We need to tell Vpython how fast to go through the loop. 25 times a second works pretty well

while(sensorData.inWaiting()==0): # Wait here untill there is data on the Serial Port

pass # Do nothing, just loop until data arrives

textline = sensorData.readline() # read the entire line of text

dataNums=textline.split(',') #Remember to split the line of text into an array at the commas

red=float(dataNums[0]) # Make variables for Red, Blue, Green. Remember

green=float(dataNums[1]) # the array was read as text, so must be converted

blue=float(dataNums[2]) # to numbers with float command

dist=float(dataNums[3]) # last number in the list is the distance

blue=blue*.7 #On my sensor, blue is always a little too strong, so I tone it down a little

if (dist>=1.5 and dist<=2.25): #only change color or target if target is between 1.5 and 2.25 inches from sensor

target.color=(red/255., green/255., blue/255.) #This keeps color from flickering.

target.pos=vector(-6 + dist,0,0) #Adjust the position of the target object to match the distance of the real target from the real sensor

The video explains each line of the code. Play around and tweak the values and see the effect on your virtual scene. Now your assignment is to take what you have learned here, and continue to expand your virtual world. Add objects to your virtual scene. Perhaps build an object for the breadboard, color sensor and arduino. I will give you several days to do this, and then when I come around for a project grade, I will want to see who has built the most impressive virtual scene. You should go well beyond the simple demonstration I have done here.

Arduino, Arduino with Python, Tutorial

Python with Arduino LESSON 4: Expanding your Virtual World

July 22, 2014 admin

In this lesson we will expand the virtual world we created in Python with Arduino LESSON 3. We will be creating a virtual world that will track a simple scene in the real world. In this project, the virtual world will track both the position and the color of a target in the real world. This lesson requires that you have the Python software and libraries installed, which we explained in LESSON 2.

Arduino Circuit — This is our circuit with the HC-SR04 ultrasonic sensor and the TCS230 Color Sensor

This Lesson will be a bit more involved, and I will take you through it step-by-step. I will need to break things into two parts. In today’s lesson we will cover the Arduino side. We will develop the software that will measure distance and color, and then send those numbers over the serial port. Then in tomorrows lesson, we will develop the Python software to create a really cool virtual graphic to display the data in a virtual world.

For this project you will need the HC-SR04 ultrasonic sensor, the TCS230 Color Sensor, the Arduino Microcontroller, and some male/female jumper wires to connect to the color sensor.

The Ultrasonic Sensor can be attached per the schematic below:

Ultrasonic Sensor Circuit — Simple Circuit for Measuring Distance

Detailed tutorial on using this sensor was described in Arduino LESSON 18, so we will not go through all the details of using the sensor here. Review that lesson if you need more help. Key point here is to connect it as seen in diagram above.

You will also need to connect up the Color Sensor.

Connecting the Color Sensor to the Arduino
Color Sensor Pin	Arduino Pin
S0	GND
S1	5V
S2	pin 7
S3	pin 8
OUT	pin 4
VCC	5V
GND	GND

Use of the color sensor was described in detail in Arduino LESSON 15. You should be able to develop to write the software yourself based on earlier lessons to make measurements from both the Color Sensor, and Ultrasonic Sensor, but if you get stuck, you can glance at my code below. Again, it is important for you to write your own code and not copy and paste mine. Mine is just a reference if you get stuck.

int S2= 7; //Color sensore pin S2 to Arduino pin 7
int S3= 8; //Color sensor pin S3 to Arduino pin 8
int outPin = 4; //Color Sensor OUT to Arduino pin 4

int trigPin=13; //Ultrasonic Sensor Trig pin connected to Arduino pin 13
int echoPin=11;  //Ultrasonic Sensor Echo pin connected to Arduino pin 11

int rColorStrength; //measured strength of red color
int gColorStrength; //measured strength of green color
int bColorStrength; //measured strength of blue color
unsigned int pulseWidth; //for measuring color strength using pulseIn command

float pingTime;  //time for ping to travel from sensor to target and return
float targetDistance; //Distance to Target in inches
float speedOfSound=776.5; //Speed of sound in miles per hour when temp is 77 degrees.


void setup() {
  // put your setup code here, to run once:
  
  Serial.begin(115200); //turn on serial port
  
  pinMode(S2, OUTPUT); //S2 and S3 are outputs and used to tell
  pinMode(S3, OUTPUT); //arduino which color to measure
  pinMode(outPin, INPUT); //This is the pin we read the color from
  
  pinMode(trigPin, OUTPUT); //Ultrasonic Trig Pin is an output
  pinMode(echoPin, INPUT);  //Ultradoinic Echo Pin is an input
  

}

void loop() {
  
  //Lets start by reading Red Component of the Color
  // S2 and S3 should be set LOW
  digitalWrite(S2, LOW);
  digitalWrite(S3, LOW);
  
  pulseWidth =  pulseIn(outPin, LOW); //Measure raw pulsewidth coming from color sensor outpin
  
  rColorStrength = pulseWidth/400. -1; //normalize number to number between 0 and 255
  
  rColorStrength = (255- rColorStrength); //reverse so that large number means strong color
  
  
  //Lets read Green Component of the Color
  // S2 and S3 should be set HIGH
  digitalWrite(S2, HIGH);
  digitalWrite(S3, HIGH);
  
  pulseWidth =  pulseIn(outPin, LOW); //Measure raw pulsewidth coming from color sensor outpin
  
  gColorStrength = pulseWidth/400. -1; //normalize number to number between 0 and 255
  
  gColorStrength = (255- gColorStrength); //reverse so that large number means strong color
  
  gColorStrength=gColorStrength + 2;
  
  //Lets read Blue Component of the Color
  // S2 and S3 should be set LOW and HIGH Respectively
  digitalWrite(S2, LOW);
  digitalWrite(S3, HIGH);
  
  pulseWidth =  pulseIn(outPin, LOW); //Measure raw pulsewidth coming from color sensor outpin
  
  bColorStrength = pulseWidth/400. -1; //normalize number to number between 0 and 255
  
  bColorStrength = (255- bColorStrength); //reverse so that large number means strong color
  
  //Now we need to exagerate the colors because readings from color sensor 
  //are all too close together. Algorithm that appears to work is to
  //take the strongest color and set to 255, take the weakest color
  //and set to zero, and then take the middle color and reduce its
  //value by 2. That is what this next segment of code does.

 if(rColorStrength>gColorStrength && gColorStrength>bColorStrength) {
   
   rColorStrength = 255;
   gColorStrength = gColorStrength/2;
   bColorStrength = 0;
 }
 
  if(rColorStrength>bColorStrength && bColorStrength>gColorStrength) {
   
   rColorStrength = 255;
   bColorStrength = bColorStrength/2;
   gColorStrength = 0;
 }
 
  if(gColorStrength>rColorStrength && rColorStrength>bColorStrength) {
   
   gColorStrength = 255;
   rColorStrength = rColorStrength/2;
   bColorStrength = 0;
 }
 
   if(gColorStrength>bColorStrength && bColorStrength>rColorStrength) {
   
   gColorStrength = 255;
   bColorStrength = bColorStrength/2;
   rColorStrength = 0;
 }
 
   if(bColorStrength>rColorStrength && rColorStrength>gColorStrength) {
   
   bColorStrength = 255;
   rColorStrength = rColorStrength/2;
   gColorStrength = 0;
 }
 
    if(bColorStrength>gColorStrength && gColorStrength>rColorStrength) {
   
   bColorStrength = 255;
   gColorStrength = gColorStrength/2;
   rColorStrength = 0;
 }
 

//Now lets measure distance to target from the ultrasonic sensor
  digitalWrite(trigPin, LOW); //Set trigger pin low
  delayMicroseconds(2000); //Let signal settle
  digitalWrite(trigPin, HIGH); //Set trigPin high
  delayMicroseconds(15); //Delay in high state
  digitalWrite(trigPin, LOW); //ping has now been sent
  delayMicroseconds(10); //Delay in low state
  pingTime = pulseIn(echoPin, HIGH);  //pingTime is presented in microceconds
  pingTime=pingTime/1000000; //convert pingTime to seconds by dividing by 1000000 (microseconds in a second)
  pingTime=pingTime/3600; //convert pingtime to hours by dividing by 3600 (seconds in an hour)
  targetDistance= speedOfSound * pingTime;  //This will be in miles, since speed of sound was miles per hour
  targetDistance=targetDistance/2; //Remember ping travels to target and back from target, so you must divide by 2 for actual target distance.
  targetDistance= targetDistance*63360;    //Convert miles to inches by multipling by 63360 (inches per mile)
 
 //Now lets print our data to the serial monitor all on one line divided by commas.
 
  Serial.print(rColorStrength);
  Serial.print(" , ");
  Serial.print(gColorStrength);
  Serial.print(" , ");
  Serial.print(bColorStrength);
  Serial.print(" , ");
  Serial.println(targetDistance);
  
  delay(150);
  
}

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int S2= 7; //Color sensore pin S2 to Arduino pin 7

int S3= 8; //Color sensor pin S3 to Arduino pin 8

int outPin = 4; //Color Sensor OUT to Arduino pin 4

int trigPin=13; //Ultrasonic Sensor Trig pin connected to Arduino pin 13

int echoPin=11; //Ultrasonic Sensor Echo pin connected to Arduino pin 11

int rColorStrength; //measured strength of red color

int gColorStrength; //measured strength of green color

int bColorStrength; //measured strength of blue color

unsigned int pulseWidth; //for measuring color strength using pulseIn command

float pingTime; //time for ping to travel from sensor to target and return

float targetDistance; //Distance to Target in inches

float speedOfSound=776.5; //Speed of sound in miles per hour when temp is 77 degrees.

void setup() {

// put your setup code here, to run once:

Serial.begin(115200); //turn on serial port

pinMode(S2, OUTPUT); //S2 and S3 are outputs and used to tell

pinMode(S3, OUTPUT); //arduino which color to measure

pinMode(outPin, INPUT); //This is the pin we read the color from

pinMode(trigPin, OUTPUT); //Ultrasonic Trig Pin is an output

pinMode(echoPin, INPUT); //Ultradoinic Echo Pin is an input

}

void loop() {

//Lets start by reading Red Component of the Color

// S2 and S3 should be set LOW

digitalWrite(S2, LOW);

digitalWrite(S3, LOW);

pulseWidth = pulseIn(outPin, LOW); //Measure raw pulsewidth coming from color sensor outpin

rColorStrength = pulseWidth/400. -1; //normalize number to number between 0 and 255

rColorStrength = (255- rColorStrength); //reverse so that large number means strong color

//Lets read Green Component of the Color

// S2 and S3 should be set HIGH

digitalWrite(S2, HIGH);

digitalWrite(S3, HIGH);

pulseWidth = pulseIn(outPin, LOW); //Measure raw pulsewidth coming from color sensor outpin

gColorStrength = pulseWidth/400. -1; //normalize number to number between 0 and 255

gColorStrength = (255- gColorStrength); //reverse so that large number means strong color

gColorStrength=gColorStrength + 2;

//Lets read Blue Component of the Color

// S2 and S3 should be set LOW and HIGH Respectively

digitalWrite(S2, LOW);

digitalWrite(S3, HIGH);

pulseWidth = pulseIn(outPin, LOW); //Measure raw pulsewidth coming from color sensor outpin

bColorStrength = pulseWidth/400. -1; //normalize number to number between 0 and 255

bColorStrength = (255- bColorStrength); //reverse so that large number means strong color

//Now we need to exagerate the colors because readings from color sensor

//are all too close together. Algorithm that appears to work is to

//take the strongest color and set to 255, take the weakest color

//and set to zero, and then take the middle color and reduce its

//value by 2. That is what this next segment of code does.

if(rColorStrength>gColorStrength && gColorStrength>bColorStrength) {

rColorStrength = 255;

gColorStrength = gColorStrength/2;

bColorStrength = 0;

}

if(rColorStrength>bColorStrength && bColorStrength>gColorStrength) {

rColorStrength = 255;

bColorStrength = bColorStrength/2;

gColorStrength = 0;

}

if(gColorStrength>rColorStrength && rColorStrength>bColorStrength) {

gColorStrength = 255;

rColorStrength = rColorStrength/2;

bColorStrength = 0;

}

if(gColorStrength>bColorStrength && bColorStrength>rColorStrength) {

gColorStrength = 255;

bColorStrength = bColorStrength/2;

rColorStrength = 0;

}

if(bColorStrength>rColorStrength && rColorStrength>gColorStrength) {

bColorStrength = 255;

rColorStrength = rColorStrength/2;

gColorStrength = 0;

}

if(bColorStrength>gColorStrength && gColorStrength>rColorStrength) {

bColorStrength = 255;

gColorStrength = gColorStrength/2;

rColorStrength = 0;

}

//Now lets measure distance to target from the ultrasonic sensor

digitalWrite(trigPin, LOW); //Set trigger pin low

delayMicroseconds(2000); //Let signal settle

digitalWrite(trigPin, HIGH); //Set trigPin high

delayMicroseconds(15); //Delay in high state

digitalWrite(trigPin, LOW); //ping has now been sent

delayMicroseconds(10); //Delay in low state

pingTime = pulseIn(echoPin, HIGH); //pingTime is presented in microceconds

pingTime=pingTime/1000000; //convert pingTime to seconds by dividing by 1000000 (microseconds in a second)

pingTime=pingTime/3600; //convert pingtime to hours by dividing by 3600 (seconds in an hour)

targetDistance= speedOfSound * pingTime; //This will be in miles, since speed of sound was miles per hour

targetDistance=targetDistance/2; //Remember ping travels to target and back from target, so you must divide by 2 for actual target distance.

targetDistance= targetDistance*63360; //Convert miles to inches by multipling by 63360 (inches per mile)

//Now lets print our data to the serial monitor all on one line divided by commas.

Serial.print(rColorStrength);

Serial.print(" , ");

Serial.print(gColorStrength);

Serial.print(" , ");

Serial.print(bColorStrength);

Serial.print(" , ");

Serial.println(targetDistance);

delay(150);

}

The key point to notice with this code is the print statements, summarized below:

  Serial.print(rColorStrength);
  Serial.print(" , ");
  Serial.print(gColorStrength);
  Serial.print(" , ");
  Serial.print(bColorStrength);
  Serial.print(" , ");
  Serial.println(targetDistance);

Serial.print(rColorStrength);

Serial.print(" , ");

Serial.print(gColorStrength);

Serial.print(" , ");

Serial.print(bColorStrength);

Serial.print(" , ");

Serial.println(targetDistance);

Notice that we are printing our color strengths and distance on one line separated by commas. It is important to note the order of the data. When we read this in Python, we will read it in as one line of text, and then we will parse it into its individual values. So, we must make note and remember the order the data is arranged in in this line.

Remember when you have your python program reading this data, you must have your serial monitor closed. For now though, run your program and look at the serial monitor to verify you are getting correct data in the expected format.

In the next Lesson, LESSON 5, we will build the Python program to create a virtual world from this data.

Arduino, Arduino with Python, Tutorial

Python with Ardiuno LESSON 3: Simple Virtual World Using Ultrasonic Sensor

July 21, 2014 admin

In this tutorial we will show how you can use Python with the Vpython library to begin to create some pretty cool graphics for presenting sensor data from the Arduino. For this tutorial, we will be using the HC-SR04 ultrasonic sensor, which you learned about in Arduino LESSON 17, Arduino LESSON 18, and Arduino LESSON 20. Please review those lessons if you are not familiar with the HC-SR04.

The circuit is very simple and can be connected from this schematic:

Since the object of this lesson is to show what you can do using Python and Vpython, I will not go through the arduino code step-by-step. You can go back to the earlier lessons for more info on the HC-SR04 sensor. The code that will allow the sensor to make distance measurements is presented again here. The one thing to note is that since we are going to be using Python to graphically present the data coming from the sensor, we want to simply send the distance measurement over the serial port, and no words or anything else, just the raw distance measurement. This will simplify things on the Python side. Remember that when we do a Serial.println() command in arduino, we can read whatever is printed into Python, as we learned in Arduino and Python LESSON 2. The code below is what you need on the Arduino side.

int trigPin=13; //Sensor Trig pin connected to Arduino pin 13
int echoPin=11;  //Sensor Echo pin connected to Arduino pin 11
float pingTime;  //time for ping to travel from sensor to target and return
float targetDistance; //Distance to Target in inches
float speedOfSound=776.5; //Speed of sound in miles per hour when temp is 77 degrees.

void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
}
 
void loop() {
  // put your main code here, to run repeatedly:
  
  digitalWrite(trigPin, LOW); //Set trigger pin low
  delayMicroseconds(2000); //Let signal settle
  digitalWrite(trigPin, HIGH); //Set trigPin high
  delayMicroseconds(15); //Delay in high state
  digitalWrite(trigPin, LOW); //ping has now been sent
  delayMicroseconds(10); //Delay in low state
  
  pingTime = pulseIn(echoPin, HIGH);  //pingTime is presented in microceconds
  pingTime=pingTime/1000000; //convert pingTime to seconds by dividing by 1000000 (microseconds in a second)
  pingTime=pingTime/3600; //convert pingtime to hourse by dividing by 3600 (seconds in an hour)
  targetDistance= speedOfSound * pingTime;  //This will be in miles, since speed of sound was miles per hour
  targetDistance=targetDistance/2; //Remember ping travels to target and back from target, so you must divide by 2 for actual target distance.
  targetDistance= targetDistance*63360;    //Convert miles to inches by multipling by 63360 (inches per mile)
  
  Serial.println(targetDistance);
  
  delay(100); //delay tenth of a  second to slow things down a little.
}

int trigPin=13; //Sensor Trig pin connected to Arduino pin 13

int echoPin=11; //Sensor Echo pin connected to Arduino pin 11

float pingTime; //time for ping to travel from sensor to target and return

float targetDistance; //Distance to Target in inches

float speedOfSound=776.5; //Speed of sound in miles per hour when temp is 77 degrees.

void setup() {

// put your setup code here, to run once:

Serial.begin(9600);

pinMode(trigPin, OUTPUT);

pinMode(echoPin, INPUT);

}

void loop() {

// put your main code here, to run repeatedly:

digitalWrite(trigPin, LOW); //Set trigger pin low

delayMicroseconds(2000); //Let signal settle

digitalWrite(trigPin, HIGH); //Set trigPin high

delayMicroseconds(15); //Delay in high state

digitalWrite(trigPin, LOW); //ping has now been sent

delayMicroseconds(10); //Delay in low state

pingTime = pulseIn(echoPin, HIGH); //pingTime is presented in microceconds

pingTime=pingTime/1000000; //convert pingTime to seconds by dividing by 1000000 (microseconds in a second)

pingTime=pingTime/3600; //convert pingtime to hourse by dividing by 3600 (seconds in an hour)

targetDistance= speedOfSound * pingTime; //This will be in miles, since speed of sound was miles per hour

targetDistance=targetDistance/2; //Remember ping travels to target and back from target, so you must divide by 2 for actual target distance.

targetDistance= targetDistance*63360; //Convert miles to inches by multipling by 63360 (inches per mile)

Serial.println(targetDistance);

delay(100); //delay tenth of a second to slow things down a little.

}

This code will be constantly sending the distance to the target out over the Serial port. On the Python side, our first task is to read that data in over the serial port. To do this, you must import the serial library. (Instructions on installing Pyserial are in Arduino with Python LESSON2.) You then create a serial object which will be used to read the data. In the sample below, we call the object ‘arduinoSerialData’. We then create a While loop that loops continuously. Inside that loop we check to see if there is any data available on the serial port, and if there is, we read it into the variable myData, and print it.

import serial #Import Serial Library

arduinoSerialData = serial.Serial('com11',9600) #Create Serial port object called arduinoSerialData


while (1==1):
    if (arduinoSerialData.inWaiting()>0):
        myData = arduinoSerialData.readline()
        print myData

import serial #Import Serial Library

arduinoSerialData = serial.Serial('com11',9600) #Create Serial port object called arduinoSerialData

while (1==1):

if (arduinoSerialData.inWaiting()>0):

myData = arduinoSerialData.readline()

print myData

Remember than in the line that creates the adruinoSerialData object, you need to change the com port to whatever com port your arduino is sending on. You can see this by looking under tools- port in your arduino IDE window. Also, this format is for windows machines. You would have to adjust for apple computers.

It is important to remember that the command .readline() in Python will read a string, so we need to remember that myData is a string, and if we want to use it as a number we will need to convert it to a float, with something like distance = float (myData). Then distance will be a normal number, not a string.

As a first demonstration lets create an object using the vPython library that is a cylinder. We will need to import the vPython library, and we will create the object before the while loop, and then inside the while loop, we will adjust the length parameter of the cylinder. We will make the cylinder with a length of six inches, we will make it yellow in color, and with a radius of 1/2 inch. Also, when we are using Vpython and dynamically updating a graphic object, inside the loop that is adjusting the graphic, we have to issue a rate() command. The rate command tells vPython how many times a second you want to go through the loop. You need to play with this command, so that it gives smooth graphics for the rate at which the Arduino is sending data. rate(20) is sometimes a good starting point. So, our code now looks like this:

import serial #Import Serial Library
from visual import * #Import all the vPython library

arduinoSerialData = serial.Serial('com11', 9600) #Create an object for the Serial port. Adjust 'com11' to whatever port your arduino is sending to.
measuringRod = cylinder( title="My Meter", radius= .5, length=6, color=color.yellow, pos=(-3,0,0))
while (1==1):  #Create a loop that continues to read and display the data
    rate(20)#Tell vpython to run this loop 20 times a second
    if (arduinoSerialData.inWaiting()>0):  #Check to see if a data point is available on the serial port
        myData = arduinoSerialData.readline() #Read the distance measure as a string
        print myData #Print the measurement to confirm things are working
        distance = float(myData) #convert reading to a floating point number
        measuringRod.length=distance #Change the length of your measuring rod to your last measurement

import serial #Import Serial Library

from visual import * #Import all the vPython library

arduinoSerialData = serial.Serial('com11', 9600) #Create an object for the Serial port. Adjust 'com11' to whatever port your arduino is sending to.

measuringRod = cylinder( title="My Meter", radius= .5, length=6, color=color.yellow, pos=(-3,0,0))

while (1==1): #Create a loop that continues to read and display the data

rate(20)#Tell vpython to run this loop 20 times a second

if (arduinoSerialData.inWaiting()>0): #Check to see if a data point is available on the serial port

myData = arduinoSerialData.readline() #Read the distance measure as a string

print myData #Print the measurement to confirm things are working

distance = float(myData) #convert reading to a floating point number

measuringRod.length=distance #Change the length of your measuring rod to your last measurement

So, this is pretty cool! It creates a little rod, and the length of the little rod dynamically changes in response to how far your target is from your sensor. This gives a very nice qualitative visual to what is happening in the real world with your sensor. Often times you also want quantitative indication of the data. We can do that by adding a label. Before the while loop, we will create a label object called lengthLabel. We will position it up just a little bit, so it is not on top of the measuringRod. We will set the label initially to ‘Target Distance is: ‘. We will also want to set box=false, since we do not want a box around our text. Then, a good height for the label is about 30 pixels. You can play around with all these settings. We create the lengthLabel before the while loop, but then inside the while loop we dynamically update the lengthLabel.text parameter. We set it to our myLabel string, which is dynamically being updated to be the concatination of the string ‘Target Distance is: ‘ and the string myData. Remember, myData is read as a string, and so we use that variable, and not distance, which is a number, not a string. Pulling this together leads to this code:

import serial #Import Serial Library
from visual import * #Import all the vPython library

arduinoSerialData = serial.Serial('com11', 9600) #Create an object for the Serial port. Adjust 'com11' to whatever port your arduino is sending to.
measuringRod = cylinder( radius= .5, length=6, color=color.yellow, pos=(-3,0,0))
lengthLabel = label(pos=(0,1,0), text='Target Distance is: ', box=false, height=30)
while (1==1):  #Create a loop that continues to read and display the data
    rate(20)#Tell vpython to run this loop 20 times a second
    if (arduinoSerialData.inWaiting()>0):  #Check to see if a data point is available on the serial port
        myData = arduinoSerialData.readline() #Read the distance measure as a string
        print myData #Print the measurement to confirm things are working
        distance = float(myData) #convert reading to a floating point number
        measuringRod.length=distance #Change the length of your measuring rod to your last measurement
        myLabel= 'Target Distance is: ' + myData #Create label by appending string myData to string
        lengthLabel.text = myLabel #display updated myLabel on your graphic

import serial #Import Serial Library

from visual import * #Import all the vPython library

arduinoSerialData = serial.Serial('com11', 9600) #Create an object for the Serial port. Adjust 'com11' to whatever port your arduino is sending to.

measuringRod = cylinder( radius= .5, length=6, color=color.yellow, pos=(-3,0,0))

lengthLabel = label(pos=(0,1,0), text='Target Distance is: ', box=false, height=30)

while (1==1): #Create a loop that continues to read and display the data

rate(20)#Tell vpython to run this loop 20 times a second

if (arduinoSerialData.inWaiting()>0): #Check to see if a data point is available on the serial port

myData = arduinoSerialData.readline() #Read the distance measure as a string

print myData #Print the measurement to confirm things are working

distance = float(myData) #convert reading to a floating point number

measuringRod.length=distance #Change the length of your measuring rod to your last measurement

myLabel= 'Target Distance is: ' + myData #Create label by appending string myData to string

lengthLabel.text = myLabel #display updated myLabel on your graphic

Lets keep playing around with this. The graphic will begin to look more like a’Virtual World’ if we create a box to represent the target we are using in the real world. I will make the box the dimensions of the real target, which is .2 X 3 X 3. Also, I will make it green, just like the target in the real world. In order to better fill our viewing window, I will move the cylinder down by about 2 inches, so its new position will be (-3,-2,0). For box type objects position is measured from the center, so I will need to also move the target box down by about .5, so it will coincide with the measuring rod. this is because 1/2 the target would be 1.5, and moving down by an additional .5 will make it coincide with the measuringRod.

Finally, I need to dynamically update the position of the target box in the while loop. I will need it to be placed at target.pos=(-3+distance,-.5,0). Along the x-axis this will put it right at the end of the rod, and will keep it properly positioned in y, as before. Bringing all this code together we get:

import serial #Import Serial Library
from visual import * #Import all the vPython library

arduinoSerialData = serial.Serial('com11', 9600) #Create an object for the Serial port. Adjust 'com11' to whatever port your arduino is sending to.
measuringRod = cylinder( radius= .1, length=6, color=color.yellow, pos=(-3,-2,0))
lengthLabel = label(pos=(0,5,0), text='Target Distance is: ', box=false, height=30)
target=box(pos=(0,-.5,0), length=.2, width=3, height=3, color=color.green)
while (1==1):  #Create a loop that continues to read and display the data
    rate(20)#Tell vpython to run this loop 20 times a second
    if (arduinoSerialData.inWaiting()>0):  #Check to see if a data point is available on the serial port
        myData = arduinoSerialData.readline() #Read the distance measure as a string
        print myData #Print the measurement to confirm things are working
        distance = float(myData) #convert reading to a floating point number
        measuringRod.length=distance #Change the length of your measuring rod to your last measurement
        target.pos=(-3+distance,-.5,0)
        myLabel= 'Target Distance is: ' + myData #Create label by appending string myData to string
        lengthLabel.text = myLabel #display updated myLabel on your graphic

import serial #Import Serial Library

from visual import * #Import all the vPython library

arduinoSerialData = serial.Serial('com11', 9600) #Create an object for the Serial port. Adjust 'com11' to whatever port your arduino is sending to.

measuringRod = cylinder( radius= .1, length=6, color=color.yellow, pos=(-3,-2,0))

lengthLabel = label(pos=(0,5,0), text='Target Distance is: ', box=false, height=30)

target=box(pos=(0,-.5,0), length=.2, width=3, height=3, color=color.green)

while (1==1): #Create a loop that continues to read and display the data

rate(20)#Tell vpython to run this loop 20 times a second

if (arduinoSerialData.inWaiting()>0): #Check to see if a data point is available on the serial port

myData = arduinoSerialData.readline() #Read the distance measure as a string

print myData #Print the measurement to confirm things are working

distance = float(myData) #convert reading to a floating point number

measuringRod.length=distance #Change the length of your measuring rod to your last measurement

target.pos=(-3+distance,-.5,0)

myLabel= 'Target Distance is: ' + myData #Create label by appending string myData to string

lengthLabel.text = myLabel #display updated myLabel on your graphic

Play around with the parameters until you get something you are happy with. Also, you can change your view of the visual once the program is running. Right mouse click and you can change your positional view of the virtual world you have created. Press and scroll the mouse wheel to change the zoom.

OK, you need to start exploring and creating your own virtual world. Go ahead and see if you can create additional objects to make your virtual world more realistic. Try creating a graphic for the sensor itself, and maybe even your PC board and arduino! You can refer to the Vpython site for more details on the 3D objects you can create, and their parameters at:

http://vpython.org/contents/docs/cylinder.html

Also, if the discription in this lesson is confusing at all please just watch the video, and I will take you through things one step at a time.

Arduino, Arduino with Python, Tutorial

Python with Arduino LESSON 2: Installing the Software

July 18, 2014 admin

There are some really incredible things we can do when we get our little Arduino to talk to the big bad Python programming language. To do that, we have to start by downloading some software. Never fear . . . it is all free and I will take you step by step through the installation. The video above shows you how to do it. If you are the impatient and technically adept type, you can download these three software packages:

1) Download and Install Python 2.7.8. Please note all my tutorials use this flavor of python. If you want to follow my tutorials, do not download a Python 3.x. Also download 32 bit version of the software, even if you have a 64 bit windows machine.

2) Download and Install Pyserial version 2.7. Again, download the 32 bit version of the software.

3) Download and install the Vpython library for 32 bit windows.

Now, lets get python and arduino talking together. First up, we need a simple program to get the Arduino sending data over the serial port. The following program is a simple program that will have the Arduino count and send the data to the serial port.

int cnt=0;
void setup() {
 
  Serial.begin(9600);
  
}

void loop() {
  
  Serial.print("I am Counting to: ");
  Serial.print(cnt);
  Serial.println(" Mississippi.");
  cnt=cnt+1;
  delay(1000);
  
}

int cnt=0;

void setup() {

Serial.begin(9600);

}

void loop() {

Serial.print("I am Counting to: ");

Serial.print(cnt);

Serial.println(" Mississippi.");

cnt=cnt+1;

delay(1000);

}

Now, open the VIDLE environment which you downloaded with the Vpython library. Once you have done that, you are ready to write a Python Program that will go out and read the data over the serial port. Full explanation is in the video. Do note, however, that the line:

arduinoSerialData = serial.Serial('com11',9600)

1	arduinoSerialData = serial.Serial('com11',9600)

This is for a windows machine. Also, the ‘com11’ has to be adjusted and set to whatever com port your arduino is talking on. You can figure that out by looking at Tools – Port on the Arduino. Set this parameter to whatever port your Arduino is talking on. Then, the baud rate needs to match as well. You can use whatever you want by Arduino and Python need to be on the same baud rate, which you set on this line of code. OK, the complete Python code to read the Arduino data from the serial port is here:

import serial #Import Serial Library

arduinoSerialData = serial.Serial('com11',9600) #Create Serial port object called arduinoSerialData


while (1==1):
    if (arduinoSerialData.inWaiting()>0):
        myData = arduinoSerialData.readline()
        print myData

import serial #Import Serial Library

arduinoSerialData = serial.Serial('com11',9600) #Create Serial port object called arduinoSerialData

while (1==1):

if (arduinoSerialData.inWaiting()>0):

myData = arduinoSerialData.readline()

print myData

Simple as that! Welcome to the world of having the Power of Python now at your fingertips.

Technology Tutorials

Monthly Archives: July 2014

Python with Arduino LESSON 6: Installing PIP on Windows

Python with Arduino LESSON 5: Finishing our Virtual Reality Example

Python with Arduino LESSON 4: Expanding your Virtual World

Connecting the Color Sensor to the Arduino

Color Sensor Pin

Arduino Pin

Python with Ardiuno LESSON 3: Simple Virtual World Using Ultrasonic Sensor

Python with Arduino LESSON 2: Installing the Software

Making The World a Better Place One High Tech Project at a Time. Enjoy!