INTERRUPTIONS: (Button)

Number pin 32: PD2 (INT0/PCINT18)) connected to D2.

From the Fabkit files (board and schematic) I created the board that adapted to it. For designing it I imported these files to Eagle and I erased all the connectors that were on the Fabkit board and then I did the schematic file for my board following the scheme that I did. This way it was easier for me. As you can see in the image I needed four analog pins to connect both sensors: the loading one and the transmit+receive one.

After designing my two sensor board, I exported the file to .png files in order to mill it with the modela. Now my board had the same measures as the Arduino board so both fit together to work as one board.

LOADING SENSOR

As I’ve never programmed in C I decided to program my sensor in Arduino. I found a very similar sensor in the Arduino library (capacitive sensing) but this sensor works in a different way because it uses digital pins instead of analog pins. This was not a problem because I connected my sensors to analog pins and they can work as digital.

I downloaded the libraries and then I installed them in order to work with them. I modified the example sketch made by Paul Badger as he was using three sensors and I only needed one. I included a LED as an output in the sketch so when the sensor detected voltage changes the LED went on or off.

#include  


CapacitiveSensor   cs_18_19 = CapacitiveSensor(18,19);        // 10M resistor between pins 18 & 19

void setup()                    
{
   cs_18_19.set_CS_AutocaL_Millis(0xFFFFFFFF);     // turn off calibration
   Serial.begin(9600);
}

void loop()                    
{
    long start = millis();
    long total1 =  cs_18_19.capacitiveSensor(30);
    if (total1 > 99){
      digitalWrite(10,HIGH); //turn Board LED on
      digitalWrite(13,HIGH); //turn Arduino Board LED on
    }
    else{ 
    digitalWrite(10,LOW);   //turn Board LED off
    digitalWrite(13,LOW);  //turn Board LED off
    }
  

    Serial.print(millis() - start);       
    Serial.print("\t");                   

    Serial.println(total1);                
    Serial.print("\t");


    delay(100);                             // arbitrary delay to limit data to serial port 
}

I had some trouble because when I uploaded the program there was a short-circuit in my board and my computer was turning off every time I connected my board to it. I discovered that the wire that connected my sensor to the board was soldered in a wrong way; I soldered also the ground wire to it. I desolder it and the program worked!

After checking that the program worked the next step was introducing Neil’s .c program to the board and checking again if the sensor worked. My instructor taught us another easier way to upload the .c program using Arduino IDE skipping the necessity of working from the terminal and with the AVRDude.

It is a very simple way in which an Arduino bootloader is needed. First of all I created a new tab in the Arduino IDE with the .c extension and then I copied the text from Neil’s .C program I modified the registers for (PORT, DDR and PIN). In my case I connected the sensor to PC2 and PC3 so in the definitions I changed “PORTB” TO “PORTC”, “DDRB” to “DDRC”, “PB2” to “PC2” and “PB3” to “PC3”. After modifying the ports pins I uploaded the program as an arduino one.

FILES:

Stepresponse (.sch)

Stepresponse (.brd)

Exterior trace

Holes

Traces

Step Response Loading hello-world