Hi how to convert analogy signal to digital signal in arduino

what is your required sampling rate and resolution, also do you know the signal voltage range of the analog input is?

If you need more information about the analog inputs of the arduino look at:

http://arduino.cc/en/Tutorial/AnalogInputPins

The analogRead instruction is described here:

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

When you have your arduino IDE installed look in the examples, analog section

heliosoph

Thanx alot I have tried to code but I when I try to run my codes I encounter an error,so can any one help me to solve this issue.

int inputPins[] = {2,3,4,5}; // create an array of pins for  inputs

int lcdPins[] = {0,1,2,3,4,5,6,7}; // create array of output pins for LEDs

void setup()

{

for(int index = 0; index < 3; index++)

{

pinMode(inputPins[index], INPUT); // declare  inputpins

}

}

void loop(){

for(int index = 0; index < 4; index++)

{

analogRead(inputPins[index]); // read input val

}

float val0=analogRead(inputPins[0]);

float val1=analogRead(inputPins[1]);

float val2=analogRead(inputPins[2]);

float val3=analogRead(inputPins[3]);

if(val0 >=0.2){

  digitalWrite( val0,HIGH); 

}

else if (val1>= 1.5){

   digitalWrite( val1,HIGH); 

}

else if (val2>val 3){

  digitalWrite(val2,HIGH);

}

else

digitalWrite( val0,LOW );

digitalWrite( val1,LOW );

digitalWrite( val2,LOW );

if (val0==LOW && val1==LOW && val2==LOW){

  Serial.println("Blood group O-");

}

else if (val0==LOW && val1==LOW && val2==HIGH){

  Serial.println("Blood group O+");

}

else if (val0==LOW && val1==HIGH && val2==LOW){

  Serial.println("Blood group B- ");

}

else if (val0==LOW && val1==HIGH && val2==HIGH){

  Serial.println("Blood group B+");

}

else if (val0==HIGH && val1==LOW && val2==LOW){

  Serial.println("Blood group A-");

  }

 else if (val0==HIGH && val1==LOW && val2==HIGH){

  Serial.println("Blood group A+");

}

else if (val0==HIGH && val1==HIGH && val2==LOW){

  Serial.println("Blood group AB-");

}

else if (val0==HIGH && val1==HIGH && val2==HIGH){

  Serial.println("Blood group AB+");

}

}

Hello Francis,

you have only a little typo in your code:

else if (val2>val 3){
  digitalWrite(val2,HIGH);
}

The space in "val 3" must be deleted:

else if (val2>val3){
  digitalWrite(val2,HIGH);
}

This should work. :-)

Thanx I have runned codes but it only displays the single blood group  o- with reference to my circuit below when I try to alternate for swichtch states.

I think you have a mess with your variables:

  digitalWrite( val0,HIGH);

val is your variable where you store your values from analogRead. In digitalWrite() you have to use a (digital) pin number. The pin you want to set to high.

Elektrix

I think you have a mess with your variables:

  digitalWrite( val0,HIGH);

val is your variable where you store your values from analogRead. In digitalWrite() you have to use a (digital) pin number. The pin you want to set to high.

Elektrix

With this code still no change observed

#include <LiquidCrystal.h>

int inputPins[] = {2,3,4,5}; // create an array of pins for  inputs

int lcdPins[] = {12,11,5,4,3,2}; // create array of output pins

LiquidCrystal lcd(12,11,5,4,3,2);

void setup()

{

for(int index = 0; index < 3; index++)

{

pinMode(inputPins[index], INPUT); // declare  inputpins

}

}

void loop(){

for(int index = 0; index < 4; index++)

{

analogRead(inputPins[index]); // read input val

}

float A0=analogRead(inputPins[0]);

float A1=analogRead(inputPins[1]);

float A2=analogRead(inputPins[2]);

float A3=analogRead(inputPins[3]);

if(A0 >=0.2){

  digitalWrite( A0,HIGH);

}

else if (A1>= 1.5){

   digitalWrite( A1,HIGH);

}

else if (A2>A3){

  digitalWrite(A2,HIGH);

}

else

digitalWrite( A0,LOW );

digitalWrite( A1,LOW );

digitalWrite( A2,LOW );

if (A0==LOW && A1==LOW && A2==LOW){

lcd.println("Blood group O-");

}

else if (A0==LOW && A1==LOW && A1==HIGH){

  lcd.println("Blood group O+");

}

else if (A0==LOW && A1==HIGH && A2==LOW){

  lcd.println("Blood group B- ");

}

else if (A0==LOW && A1==HIGH && A2==HIGH){

  lcd.println("Blood group B+");

}

else if (A0==HIGH && A1==LOW && A2==LOW){

  lcd.println("Blood group A-");

  }

else if (A0==HIGH && A1==LOW && A2==HIGH){

  lcd.println("Blood group A+");

}

else if (A0==HIGH && A1==HIGH && A2==LOW){

  lcd.println("Blood group AB-");

}

else if (A0==HIGH && A1==HIGH && A2==HIGH){

  lcd.println("Blood group AB+");

}

else

lcd.println("device error");

}