As a sideproject I decided to design a simple experiment and use Arduino to measure the friction coefficient of an object sliding on a given material.
Ideally we would like our first object to slide (not roll) on a sheet of a given material as below:
If we know the angle (we can easily set it) and the mass of the wooden block, then the only unknown variable is the friction coefficient and we can easily estimate it by measuring how long it took for the block to go over a certain distance x.
At the beginning of this summer, I was asked to provide a simple (and possibly cost-effective) solution to a simple problem: how can I do in order for my garden LED lights to turn themselves on and off according to the sunlight?
There are plenty of ready to use circuits and tools that one can use to answer this question, however I decided to try and design something “new” empowered by what I recently learned about NPN transistors, relays and LT-Spice IV. Let me talk you through my workflow:
The problem and the setting:
The LED lights which provide illumination in the garden are powered by a solar panel which during the day charges the battery. At night, the stored energy is used to power the lamp. The solar charge controller ensures that the charging process is smooth and that everything is going as it should during the charge and discharge processes. Since the solar charge controller is very minimal, it does not have a timer or a switch to turn on and off the lights. A manual switch is therefore used instead (not shown in the picture and to be replaced by this project). The lamp is a 12V 4.5W LED lamp.
The solution
Hi everyone! I have just completed a first, very basic GUI to get the Aduino module (which by the way you can find here) more user friendly.
The GUI is still a “Beta” version since I have created it with PyQt4 which I started learning only 3 days ago. I bet there are plenty of features which could be improved. I am probably going to revise and update this GUI, however here is a first “raw” version which, as far as the connection and communication with Arduino Uno is concerned, works fine.
This application is for educational purpose only, any commercial purpose is excluded.
You can download the executable for windows here. For Mac and Linux users, the source code is included in the zip folder however I am not sure the program will work since I have no experience with those operating system and their USB settings. Feedbacks are much appreciated.
Here are some screenshots and some useful information:
This is the main screen. The three buttons at the bottom essentially sum up everything that this program should help you doing.
First of all, you need to connect Arduino Uno to the USB port and load your program in.
Then you can click on connection on your GUI and click “Set up connection”. The default port is com3 and 9600 baud. You can easily change these default settings in the connection menu available in the GUI.
Once the connection has been established you can start interact with Arduino Uno.
By clicking on the button “Read from Arduino” the program asks you how many lines to read, there’s still no default values however I suggest to read not more than 100 lines since the program might slow down or crash.
By clicking on the button “Send to Arduino”, the program asks you to enter the data to send. You can enter one of the three data types showed below in the following form:
1. Integer: 2
2. Character: b
3. List: [2,3,4,5,6,7,8]
The list can be as long as you want it to be.
Hope this is useful.
Today I am going to talk about a particular topic which overlaps Arduino and computer programming.
Last month I was watching video about electronics and thinking about the solar controller which many solar stand alone kits use. For some reason they do not behave as they should (i.e. cut the power to the lights when the sun is rising and give full power in the evening). However, a far more important point is that for this kind of controller a centralized control system is not available. Therefore I had a great idea: let’s try to program a board such as Arduino, to do the job.
I bought an Arduino Uno, the basic model, which I guess is suitable for beginners as myself. You can check more details here.
Arduino is an open source project and can be programmed in a language which is similar to C. This point is fine, since I have some knowledge of C and can get by quite easily with beginner projects. Once the main code has been loaded on Arduino, you can interact with the board through the USB and the “shell”, and, for instance, give instructions to trigger some control flow structure such as if-if else- else. However, in some cases it does not work (still do not know why) or it is impractical, since you can enter only one value at time. It would be nice to control the board with some external tool which could let you write some script to execute. It turns out that there is a module which enables you to do such operations. This module is pySerial. It can be downloaded here and is available for Python 3 as well!
The module is great! It works really smooth and in a linear manner, as it should. However, Arduino accepts only raw bytes and binary code as input therefore some little amendments must be made to be able to communicate with it through Python 3. Note that there are some differences with Python 2 which I will not cover.
First of all, Python 3 wants naturally work with ASCII characters, therefore when sending an integer to Arduino Uno, our sweet board will understand anything but what we have sent. For characters such as ‘a’, the matter is somewhat at ease, since you just need to send the character with a b in front of it: b’a’. On the opposite side, when reading data, you need to convert it into a readable format. To solve all these “problems” I decided to build a simple class which essentially is a wrapper of some functions of Serial and can be used directly to send characters, lists and integers to Python. Perhaps I will add also the possibility to send floats and strings although I am not sure the latter can be send and understood from the board.
Here is a basic example of communication with Arduino Uno through Python 3.
First of all we need to load the following code to Arduino Uno. This simple code lights a LED light according to the value of readData which is read from the USB port. Serial.print prints out the value of readData to the USB port.
For instance, to control the board in this case, you can use this Python code:
However, writing this code again and again is boring and can easily lead to mistakes. Therefore I decided to built a class whose name is Arduino
By creating an Arduino object using the ArduinoClass, you can call the following methods:
I am also working on a GUI with PyQt4 for this script. I will keep you posted.
The source code of the ArduinoClass is available here.
Hope this is useful!
