Gobetwino: Arduino talking to Excel

Gobetwino is pretty easy use. The Arduino can now send words to the serial port and Gobetwino takes them as commands and does handy stuff like create csv’s send email etc. I’ve tested out this program by making the Arduino log the voltage of a discharging capacitor and send the details to Gobetwino to make a csv for Excel.

Circuitry

 

Log discharging capacitor, use FET's instead of BJT's if you want to avoid 0.6V drop

Arduino Code

//    Arduino code
//    Arduino to Excel using Gobetino
//      - Arduino logs 100 values 

//      - Gobetwino takes these values and puts them in data.txt 

//      - Excel Imports this file as a csv and draws the graph

// ==========< option 1 >========== 

//      FIRST logs data to chip's sram,  THEN sends to pc using Gobetwino  

//      - 1028 bytes can be stored  

//      - readings are taken fast this way 

// ==========< option 2 >========== 

//      log straight to .txt with Gobetwino  

//      - approximately a max of 37 readings/sec , depending on the serial speed you choose

//      - this way is safe (unlimited with the chips 1024 bytes of SRAM)  

// ============< variables >==========

//  A0   -   Vcap 

//  D3   -   button/switch    (trigger)

//  D4   -   transisters to charge & discharge cap 

//  D5   -   LED 1

//  D6   -   LED 2 const int size = 100;

// number of readings (size of array must be constant) 

// don't make it too big, arduino has limited memory const float Vss = 5.0;

// if you want to be more accurate measure arduino's Vss int arrayms[size]; 

// an arary to store time 

int arrayA0[size];

// an arary store voltage 

int a;

// counter 

long startTime;  
void setup() { 

pinMode(2, INPUT); // button 

pinMode(3, OUTPUT); // pin connected to transistor bases

pinMode(4, OUTPUT); // LED 1 

pinMode(5, OUTPUT); // LED 2    LED's are used to show what stage the chip is in

pinMode(6, OUTPUT); // LED 3  
Serial.begin(9600);

}
void loop() {
//////////////////////////////////////////////////////////////////////////////////////////////////////////////////////// /*  test stuff   

while(digitalRead(3)){}              // wait until I press pin 3 (trigger button) 

while(!digitalRead(3)){} 

Serial.println("#S|CPTEST|[]#");     // Use the CPTEST copy file command to make a copy of a new empty logfile 

while(digitalRead(3)){}              //wait until I press pin 3 (trigger button) 

while(!digitalRead(3)){}  
 digitalWrite(3, HIGH); // start charging capacitor 

delay(500); // wait 500 ms for the capacitor to charge 

while(digitalRead(2)){ digitalWrite(6, HIGH);   }

digitalWrite(6, LOW); 

digitalWrite(4, HIGH); // LED 1 tells you the capacitor should be charged
wait_until_pin_3_is_pressed(); // ------------------------------ 

a=0;

startTime = millis(); 

digitalWrite(3, LOW); // discharge capacitor 

while(a <= size )   {

arrayms[a]= millis()-startTime; // record time 

arrayA0[a]= analogRead(0); // record Vcap 

a++;

delay(1); // wait however ms before taking the next reading }

digitalWrite(4, LOW); // If LED 1 doesn't switch off, there is a problem in stage 1

digitalWrite(5, HIGH); // LED 2 tells you that Stage 2 is ready to start 

wait_until_pin_3_is_pressed(); 

// ----------------------

a=0; 

while(a <size){

Serial.print("#S|LOGTEST|["); 

// #S  ->  tells gobetwino to listen

// |LOGTEST|[  ->  Gobetwino runs the LOGTEST command I made,  

// which opens data.txt in this app's folder 

// NOTE: there must already be a data.txt in the folder 

printDouble( double(arrayms[a])/1023*Vss, 3); 

Serial.print(";");

printDouble( double(arrayA0[a])/1023*Vss, 3);

Serial.println("]#");

// # tells Gobetwino to stop paying attention

a++;

}

digitalWrite(5, LOW); // if LED2 doesn't switch off you're stuck in Stage 2 

} // end of void loop() 

// somebody elses function I found to print doubles

void printDouble( double val, byte precision){ 
// prints val with number of decimal places determine by precision 
// precision is a number from 0 to 6 indicating the desired decimial places 
// example: printDouble( 3.1415, 2); 
// prints 3.14 (two decimal places) Serial.print (int(val));
 //prints the int part if( precision > 0) { Serial.print(".");
 // print the decimal point 
unsigned long frac; unsigned long mult = 1; 
byte padding = precision -1; while(precision--)       mult *=10; 
if(val >= 0) 
 frac = (val - int(val)) * mult;
 else frac = (int(val)- val ) * mult;
 unsigned long frac1 = frac;
 while( frac1 /= 10 )       padding--; 
while(  padding--) Serial.print("0"); 
Serial.print(frac,DEC) ;   } } 
void wait_until_pin_3_is_pressed() {
 while( !digitalRead(2) ){   } 
while( digitalRead(2) ){   } 
 } 

How Gobetwino works

Before trying to use this program you should read the Gobetwino pdf. You basically have to open Gobetwino and create a command to handle .txt files. I did this by opening Gobetwino and creating a LOGTEST command to open log.txt

1. Click on the Commands menu
2. Selecting LGFIL (Log File command)
3. Select the file location of an existing .txt file (data.txt in this case)

Now when the Arduino serially prints LOGTEST a .txt file is opened.

   Serial.print("#S|LOGTEST|[A,B,C]#");

• #s tells Gobetwino to pay attention
• |LOGTEST| is the command I created with Gobetwino to open data.txt
• [A,B,C] are variables printed to the file
• # tells Gobetwino to stop paying attention

Summary

1. Upload the code to the Arduino
2. Create the LOGTEST command with Gobetwino
3. Press the button on your circuit (capacitor discharges)

I then import the .txt with excel and create the following graph

The voltage of the discharging capacitor

Notice the capacitor doesn’t fully discharging because I used BJT’s instead of FET’s.