Application Programming

As finals draw nigh, I have been forced to streamline my efforts. Fortunately, I already had a working accelerometer board from input week. Instead of learning a whole new language, I tried out firefly for grasshopper an interface for my fabduino. I started with my original code from input week, but the values came in a single line like this

"2.37-15.23" or "-30.1212.71" to denote x=2.37 y=-15.23 or x=-30.12 y=12.71

With limited text editing capability, grasshopper was not able to cleanly separate the values. I returned to the arduino code and changed the output to be separated by the letter <a> instead of a tab character. I also reduced the output of the fabduino to the bare minimum milli-g's and left the conversion into angle for the computer.

Here's my code

// these constants won't change: const int xPin = 4; // X output of the accelerometer const int yPin = 3; // Y output of the accelerometer void setup() { // initialize serial communications: Serial.begin(19200); // initialize the pins connected to the accelerometer // as inputs: pinMode(xPin, INPUT); pinMode(yPin, INPUT); } void loop() { // variables to read the pulse widths: int pulseX, pulseY; // variables to contain the resulting accelerations float accelerationX, accelerationY; //angles float angleX, angleY; // read pulse from x- and y-axes: pulseX = pulseIn(xPin,HIGH); pulseY = pulseIn(yPin,HIGH); // convert the pulse width into acceleration // accelerationX and accelerationY are in milli-g's: // earth's gravity is 1000 milli-g's, or 1g. accelerationX = ((pulseX / 10) -500)*8 ; accelerationY = ((pulseY / 10) -500)*8 ; //angleX = (asin(accelerationX / 1000))*(200/(3.141592)) ; //angleY = (asin(accelerationY / 1000))*(200/(3.141592)) ; // print the acceleration Serial.print(accelerationX); // print a tab character: Serial.print("a"); Serial.print(accelerationY); Serial.println(); delay(10);

I also changed the delay to 10ms so the animation would be smoother.

 

Here is my Grasshopper/Firefly definition.

It's pretty simple, the basic stages are,

1. establish connection with the port/fabduino

2. ocne reading the data from the serial port, convert the data into a coordinate pair using a "text replace" function where I change the letter <a> to a comma.

3. This coordinate pair can now be converted to angles using arcsine(<value>/1000)

4. create a surface and a box

5. Rotate the geometry according to the values from step 3

6. Separate the rotated geometry and change it's appearance to make the app clearer.

 

Here is the finished thing working. I forgot to change the timer in grasshopper, so it still only updates every second.

 

 

 

I would like to learn python for these types of applications, but I like how grasshopper is a visual interface that basically imitates the steps I would take in a written code.