gps guided car

Using Arduino Programming Questions
1

hi :slight_smile:
i wanna set a track to a robot car using GPS of my mobile
So,, i make an app by app inventor which take the longitude and latitude of my current location & my destination and do some calculations so that i can get the distance between the two places
and after that it sends the distance to the arduino using "call BluetoothClient.send text" in app inventor
the problem is that i can't convert the received distance to a float number so that i can use it in my code
i made a sample code just to explain what i mean

void setup()
{
  Serial.begin(9600);
}

void loop()
{
  if(Serial.available()>0)
  {
  float a=Serial.read();
  Serial.println(a);
}
}

the distance in the app was 2.01413
and in tha serial monitor was :

50.00
46.00
48.00
49.00
52.00
49.00
51.00

which is the ascii code of 2.01413
how could i convert it to be float " 2.01413" ??

2

You better have a big track, since GPS is only good to 10 meters or so.

Gather all the characters into a string and convert it with strtod().

3

Unfortunately i can't know how to put all the characters into one string
i used String distance=Serial.read();
but there's an error

no known conversion for argument 1 from 'int' to 'const

4

Serial.read( ) reads on character. You need to collect all the characters in your number and then get the float value out of that.

5

You need to collect all the characters in your number and then get the float value out of that.

i don't know how to do that ..

6 
void setup()
{
  Serial.begin(9600);
}

void loop()
{
  if(Serial.available())
  {
    float a = Serial.parseFloat();
    Serial.println(a);
  }
}
7 
void setup()
{
  Serial.begin(9600);
}

void loop()
{
  if(Serial.available())
  {
    float a = Serial.parseFloat();
    Serial.println(a);
  }
}

it works but it prints only the first four digit
so if the sent distance is 1.45851
it prints 1.45

8 
    Serial.println(a);

default is two decimals, try:

    Serial.println(a , 6);
9

it works perfectly
thank you :slight_smile: