Week 13: Interface and Application Programming

This week I had to design an interface which interacted with an input or output device I had used before. I decided to use my potentiometer as the aforementioned input device. I have zero experience or skill working with interfaces and applications, so I had to check past assignments from UTEC's students. I decided to use Processing as my programming environment and Arduino as a way to program my board. I read that I had to communicate the PCB with processing via the serial port, and my input device from week 11 couldn't do that, because I used an AtTiny 45, which does not support serial communication. Luckily, I had a modified Satsha Kit from week 9 (embedded programming - I knew they'd come handy) and I added a potentiometer board as an extra.

This is the "design" for the potentiometer board. It is quite simple since it does not require any extra resistors or components.

Milling the board. I used Fab Modules as a CAM environment, with the same parameters I used during "Electronics Design".

I then started learning how to work with procressing. I started by checking Alejandro's and Alexandra's repositories. They both worked with processing during their academies, and they were willing to help me, so I tried learning and watching some tutorials.

I also started working with Arduino simultaniously, and I followed this tutorial to learn how to communicate both programs.

My idea was to create a "Hyperspace" effect, using moving circles as stars, with varying speed. The speed will depend on the information given by the potentiometer through the serial port. The code is rather simple, I receive a string from the serial port, and trim it to eliminate the newline. I then transform the string to a float, and map the information between 0 to 200. This data will represent the speed at which the stars will move. The stars are created within a class, in a different tab.

This is a picture of the code working, but not with information given by the potentiometer, but rather from the mouse. The code maps the position of the mouse in the X-axis, and changes the speed.

Finally, I started working with the Arduino IDE. The code is also simple. The potentiometer is connected to an analog input, which reads the incoming data and stores it in a variable. The values are sent via the serial port to processing, using an FTDI cable.

This is a picture of my working environment, the Arduino IDE, and both processing sketches, one for the main code, and one for the stars.

This is how the code works:

1. The potentiometer is connected to the satsha kit. It is connected to one of the analog pins. Within the code, the pinMode is defined as an INPUT. The processor reads the data as a number between 0 and 1023. It then maps it between 0 and 255, just as I did with my code for "Input devices week". Finally, the number is sent to processing via the serial port.
2. The main tab within processing (the Hyperspace_Car tab that is) receives the data and maps it between 0 and 200. But before, I had to define the port through which the program would receive the input. Once it maps the data, a parameter called speed acquires the value and determines the speed at which the the stars move. It also modifies the diameter of a circle situated in the center of the interface, which grows as the speed increases.
3. The stars tab creates a random number of stars within the interface, it just defines a class.

Here's a video of the interface working with the potentiometer.

Below, you'll find links to my board and codes:

1. Arduino Code
2. Hyperspace code
3. Star Class processing
4. Schematic
5. Board