How to send float over serial

Question

What\'s the best way to send float, double, and int16 over serial on Arduino?

The Serial.print() only sends val

Answer 1

hm. How about this:

void send_float (float arg)
{
  // get access to the float as a byte-array:
  byte * data = (byte *) &arg; 

  // write the data to the serial
  Serial.write (data, sizeof (arg));
}

Answer 2

This simply works. Use Serial.println() function

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

}

void loop() {
  float x = 23.45585888;
  Serial.println(x, 10);
  delay(1000);
}

And this is the output:

Answer 3

Use the Firmata protocol. Quote:

Firmata is a generic protocol for communicating with microcontrollers from software on a host computer. It is intended to work with any host computer software package. Right now there is a matching object in a number of languages. It is easy to add objects for other software to use this protocol. Basically, this firmware establishes a protocol for talking to the Arduino from the host software. The aim is to allow people to completely control the Arduino from software on the host computer.

Answer 4

Structures and unions solve that issue. Use a packed structure with a byte sized union matching the structure. Overlap the pointers to the structure and union (or add the union in the structure). Use Serial.write to send the stream. Have a matching structure/union on receiving end. As long as byte order matches no issue otherwise you can unpack using the "C" hto(s..l) functions. Add "header" info to decode different structures/unions.

Answer 5

Does size matter? If it does, you can encode each 32 bit group into 5 ASCII characters using ASCII85, see http://en.wikipedia.org/wiki/Ascii85.

Answer 6

Perhaps that is best Way to convert Float to Byte and Byte to Float,-Hamid Reza.

int breakDown(int index, unsigned char outbox[], float member)
{
  unsigned long d = *(unsigned long *)&member;

  outbox[index] = d & 0x00FF;
  index++;

  outbox[index] = (d & 0xFF00) >> 8;
  index++;

  outbox[index] = (d & 0xFF0000) >> 16;
  index++;

  outbox[index] = (d & 0xFF000000) >> 24;
  index++;
  return index;
}


float buildUp(int index, unsigned char outbox[])
{
  unsigned long d;

  d =  (outbox[index+3] << 24) | (outbox[index+2] << 16)
    | (outbox[index+1] << 8) | (outbox[index]);
  float member = *(float *)&d;
  return member;
}

regards. `