Interface and application programming

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First of all I had to re-do the board which I did for inputs' assigment, as I broke it. It was a good excuse to try the design improvement I did, and documented it in the assignment.



I used as well three female to female pins which make the connection more robust and more difficult to break the pcb.



I took Neil's code, the one I used for the previous assignment, trying to understand how it was coded. The part in blue are the constants and the formula to get the value from the sensor.



I took these same values and put them into Processing, to see if I could use it. I had to adapt a bit the code, as the language between Python and Processing it's not the same (they change a bit some small details). I selected directly the port I wanted it to read through serial. The interface worked at pretty much the same level than the Python script. Remember the board still had the C file inside.



This is the code I used:

                    
                    
import processing.serial.*;

Serial myPort;  // Create object from Serial class
float val;      // Data received from the serial port
float sensorData; // Data received from the serial port with 1,2,3,4 framing numbers filtered out
float low=0;
float high=0;
float value=0;
float byte1 = 0;
float byte2 = 0;
float byte3 = 0;
float byte4 = 0; 
float filt = 0;
float us = 0; 
float cm = 0; 
float eps = 0.1; // change the value to float
//float nsamples = 100.0; // copy from the python file


void setup()
{
  size(1000, 300);

  println(Serial.list());
  myPort = new Serial(this, "/dev/tty.usbserial-FTHBQ1K0", 9600);
  // change the port

}

void draw()
{
  while (myPort.available() > 0) {    // If data is available
    byte1 = byte2;
    byte2 = byte3;
    byte3 = byte4;
    byte4 = myPort.read();
   
    if ((byte1 == 1) & (byte2 == 2) & (byte3 == 3) & (byte4 == 4)){} // Filter out the framing numbers: 1,2,3,4
    else {
    low = myPort.read();
    high = myPort.read();
    value = (256*high + low); 
    
     filt = (1-eps)*filt+eps*value;
     us = filt/8.0; 
     cm = us/58.0;   
      

       println("THE VALUE IS " + cm); //print to the screen
    }
    
    background(322);  // Set background to white
    int scale = 10 ;
    rect (20,20,cm*scale,20);
  }
}

Another thing I wanted to try is to make it work directly with Arduino, as I did in the inputs' assignment too, but this time sending the data to Processing and then reading it directly through there. First I tried an easy code, just to see if I could read what I was sending through the serial port with Arduino to processing.



The code here:

#include SoftwareSerial.h 

SoftwareSerial mySerial(1, 2); // RX, TX

void setup() {

pinMode(2,OUTPUT); 

  mySerial.begin(4800);
  mySerial.println("Hello, world?");
}

void loop() { 
  
  mySerial.println("Hello");
}

I then opened processing and start coding to receive the data from Arduino



with the following code:

import processing.serial.*;

int cm = 0;

Serial myPort;  // Create object from Serial class


void setup()
{
  size(800, 200);

  println(Serial.list());
  myPort = new Serial(this, "/dev/tty.usbserial-FTHBQ1K0", 4800);
  // change the port

}

void draw()
{
  while (myPort.available() > 0) {    // If data is available
  String temp = myPort.readStringUntil('\n');
  if(temp!=null){
  cm = Integer.parseInt(trim(temp));
  println("THE VALUE IS " + cm); //print to the screen
    }
    
    background(322);  // Set background to white
    float scale = 10 ;
    rect (20,20,cm*scale,20);
  }
}
        

Here's the result. Processing read fine the data sent with the Arduino, and even quicker than Python.



A small video here shows how it works


pass: fab


Download all the files here