Here is a little Programm i am using for two Analog inputs. Later i want to calculate the difference. But for some reason it's always 0. That drives me crazy
It's a really short and easy code, maybe someone could help me figure out what i did wrong
/*
AnalogReadSerial
Reads an analog input on pin 0, prints the result to the serial monitor.
Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.
This example code is in the public domain.
*/
// the setup routine runs once when you press reset:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}
void loop() {
// read the input on analog pin 0/1:
int sensorValue1 = analogRead(A0);
int sensorValue2 = analogRead(A1);
long Dehnung = 1;
long Ua = 0;
long Ub = 0;
// print out the value you read:
Serial.println("Ua: ");
Serial.println(sensorValue1);
Serial.println("Ub: ");
Serial.println(sensorValue2);
delay(1000); // delay in between reads for stability
Dehnung = Ua - Ub;
Serial.println("Dehnung: ");
Serial.println(Dehnung);
}
See how you go with this code.....your version was subtracting 0 from 0 every time (the variables Ua and Ub are never set after they are declared as 0), so the answer was always going to be zero.
/*
AnalogReadSerial
Reads an analog input on pin 0, prints the result to the serial monitor.
Attach the center pin of a potentiometer to pin A0, and the outside pins to +5V and ground.
This example code is in the public domain.
*/
long Ua = 0;
long Ub = 0;
long result=0;
// the setup routine runs once when you press reset:
void setup() {
// initialize serial communication at 9600 bits per second:
Serial.begin(9600);
}
void loop() {
// read the input on analog pin 0/1:
Ua = analogRead(A0);
delay(10);
Ub = analogRead(A1);
delay(10);
result=Ua-Ub;
// print out the value you read:
Serial.print("Ua: ");
Serial.println(Ua);
Serial.print("Ub: ");
Serial.println(Ub);
Serial.print("Dehnung: ");
Serial.println(result);
}
While true for uninitialized GLOBAL variables it's a bad assumption that uninitialized LOCAL variables will be zero. Uninitialized LOCAL variables will contain whatever garbage is on the stack.
Something a little more easy to follow -
const unsigned long ONE_SECOND = 1000UL;
void loop()
{
int Ua = analogRead(A0);
Serial.print("Ua: "); Serial.println(Ua);
int Ub = analogRead(A1);
Serial.print("Ub: "); Serial.println(Ub);
delay(ONE_SECOND);
int Dehnung = Ua - Ub;
Serial.print("Dehnung: "); Serial.println(Dehnung);
}
void setup()
{
Serial.begin(9600);
}
