Reading analog values Arduino

The ADC is 10 bits of resolution.  2^10=1024.  You have thrown away half of your range: 0 to 2.5 volts.  Consider doing something to correct that.

At some point you will divide by 10 > 8 =2^3.  So, the lower three bits are of no value any where along the line.  I recommend [0..63]/8 sampled and summed 8 times will produce the average [0..63].    Use a right shift of 3 positions to do the /8 for efficiency.

Since the [0..63] vector must use 16 bit integers you could do [0..63]/8 sampled and summed 16 times then [0..63]/2 will produce the average.

Thanks for your informative reply..

Actually output range can be changed depending on the circuit I use so that the output range can be between 0V-5V (eg voltage divider circuit..)..nevertheless,your point was pretty cool,I did not consider it ..So what do you think about the code? are there any points missing? Thanks a lot..

PS:I will add threshold value also..I will not show the output values which are lower than threshold..

It compiles with Arduino 0023 after removing the two extra } at the end. 

Sorry, I am too tired to read it in depth right now. I would try to stick to integer everything, but that is just me.

Hello everyone again;)

So any other recommendation or ideas?

Thanks..

Are you wanting to do the computed average for samples sets 1..10 and then a separate computed average for sample sets 11..20, etc?    Or are looking to have a sliding window on the data input stream so you can compute the average for arbitrary sample sets x..x+9?   

Can you add more comments to you code?

actually not..let me make it clearer.--my sensor output gives 64 different voltage values for each loop. [its a sensor matrix 8*8 , 8 rows and 8 columns..i used 2 counter with different speed so that i can scan the whole matrix--after 1 scan i will get 64 different values 64x1] ..I want to make 10 loops[ 10 scans] and show the averaged value at the end..I have put the image in the previous answer..

readings[index_readings] = analogRead(inputPin); //Read the data from sensor (64 values)

// advance to the next position in the array:
index_readings = index_readings + 1;

The above is not how arduino code works.

Using a nested loop structure is required.

for (i =0; i < numLoop; i++;)

{

     for (j=0; j < numReadings; j++)

     {

          readings[i,j] = analogRead(inputPin);     // opt to >>3  which is /8 if going that way

          // possible other i/o or calc here

     }

}

http://arduino.cc/en/Reference/For

for (initialization; condition; increment) {

//statement(s);

}

Hello Billabott;

Thank for your reply.. I modified the codes a bit..

float readings[64];                    // the readings from the analog input after each scan
float totReadings[10];               //total readings from the analog input  scan
int i = 0;                                // the index of the current reading
int j=0;                                   // the index of the current loop
float average[64];                     //Averaged value
int inputPin = A0;                     //Determine the pin

void setup()
{
Serial.begin(9600);                  
}
void loop() {
   // initialize all the readings
  for (int i = 0; i < 64; i++)
  // initialize all the loops
  for(int j=0; j<10;j++)
  // read from the sensor: 
 
  totReadings[i,j]=totReadings[i,j]+ readings[i];
  readings[i] = analogRead(inputPin);  //Read the data from sensor (64 values)
  
  //Take the average value
  average[64]=totReadings[i,j]/j;                        //Averaged value divided by 10(number of loops)

  Serial.println(average[64]);                              //Print the averaged value 64x1

Great!   But you need for use the curly braces open and close, { } ,to control the range of the for statements.

Hello again,

I have noticed some mistakes..and marked them using arrow..

float readings[64];                 // the readings from the analog input after each scan

float totReadings[10];           //total readings from the analog input scan                                 -->>>one dimension array but below i used it as 2-dim array??

int i = 0;                            // the index of the current reading

int j=0;                            // the index of the current loop

float average[64];            //Averaged value                                                                           -->>here must be 63..becoz i have 64 values..0...63 ??

int inputPin = A0;          //Determine the pin

void setup()
{
Serial.begin(9600);
}
void loop() {
// initialize all the readings
for (int i = 0; i < 64; i++)

{

for(int j=0; j<10;j++)

{
// read from the sensor:

totReadings[i,j]=totReadings[i,j]+ readings[i];               //               --->>>>> here i have used totReadings as two-dimensional array ??
readings[i] = analogRead(inputPin); //Read the data from sensor (64 values)

//Take the average value
average[64]=totReadings[i,j]/j;                                    //Averaged value divided by 10(number of loops)   

Serial.println(average[64]);                                         //Print the averaged value 64x1

}

}

}