This week the assignment was wrote an application that interfaces with an input &/or output device.

I chose to focus my attention on an output interface device useful for my final project. I created a computer interface to drive and to control my robot.

I used for the first time Python, for this reason I started studying some good tutorials and participating at the webinar of the Fab Lab Frosinone to dominate the basic commands. Then I studied on the web page of Arduino and other tutorials, the interaction between writing and reading serial.

The hardware part of this assignment I used::

- 2 dc motors 12 V (Recovered from a broken printer);

- Fabkit;

- FTDI wire connector (to connect the Fabkit to computer)

- 2 shield H bridge

- Connector / wire

- Power supply (replaced with a Battery 12 V)

I built a simple structure to connect the two dc motors and give more stability; I connected the H bridge shields to Fabkit, dc motors and power source. For consignments problem, I could not use the wi-fi shield for this assignment, for this reason I used the FTDI connector to receive from the computer the “serial command”.

First I downloaded Python 2.7 (I chose this version to start because have more forum and tutorial) and I added the Tkinter library interface at the basic library.

Using Arduino IDE I wrote the C code; I programmed the microcontroller to read (using the serial port) the signals coming from the interface:

if (Serial.available()) { command = Serial.read(); }

and I imposed on each individual signal a basic command:

(Forward command example) if (command == 'A'){

analogWrite(hbridge_in1,150); //input1 dc motor n°1

analogWrite(hbridge_in2,0); //input2 dc motor n°1

analogWrite(hbridge_in3,150); //input1 dc motor n°2

analogWrite(hbridge_in4,0); //input2 dc motor n°2

}

Then I wrote in Python the code and the GUI Design:

- Before to start the code I re-called the librarys:

(example) from Tkinter import *

import serial;

- I defined who’s the “reader/writer” of serial command:

Fabkit = serial.Serial();

- Then I defined the serial port and how to read/write the data;

- I finally set each command. In my case I have 4 types of command:

1)def serialCTRL(): # to periodically check the connection

print("OK")

dati = arduino.read(1)

print(dati)

window.after(300, serialCTRL) ;

2)def Connect(): # to connect the interface to the board (in my case from Serial port COM4)

try:

global Fabkit

Fabkit = serial.Serial("COM4",9600,timeout=0);

window.after(1000, serialCTRL) ;

3)def Forward (Command): # to send a signal (Forward command example)

try:

global Fabkit

Fabkit.write(Command)

print "%s" % (Command)

return;

-I closed the first part:

window = Tk ()

var = StringVar();

- Finally in the GUI Design Part I set the graphics interface and the elements that compose it, I assigned to each component the commands described before:

(Forward command example) button_1 = Button(text="F",command= lambda: Forward('A'), width = 12, borderwidth = 5, relief = GROOVE, bg="#3b5061", fg="white", font=("Helvetica",50)).grid(row=0, column=5)

- To close the code and enable the loop, I wrote:

window.mainloop();

I created a really simple command interface to control my robot, but I want to go into that and produce a better interface for the final project. I started to study also Processing.

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