8 years, 5 months ago.

If things will always be the same format then sscanf() is the easier approach.

Strtok() and atof() is a lot more flexible since you can change the expected format based on the values in earlier fields or handle empty fields.

If you want to do anything else at the same time then use an interrupt to capture the serial data.

In the example below the serial interrupt collects the data and then when it receives a new line character it attempts to parse it for the 3 values. If that works it updates the values of some global variables and sets a flag indicating that there is new data from the serial port.

When the main loop isn't busy with something else it can then check for new serial data.

If you need to read from the mpu6050 at a regular rate then I'd recommend using a ticker to read the values and then use a similar method of setting a flag for the main loop when there is new data. That way the main loop isn't collecting any data directly, that is all done on interrupts. All the main loop does is constantly check for new data and handle it as it arrives.

volatile bool newData = false;
volatile float inputs[3];

onSerialRx() {

  static char serialInBuffer[32]; 
  static int serialCount = 0;

 while (pc.readable()) { // in case two bytes are ready
   char byteIn = pc.getc();
   if ( (byteIn == 0x0D) || ( (byteIn == 0x0A)) { // if an end of line is found
    serialInBuffer[serialCount] == 0;                 // null terminate the input
    float x,y,z;
    if (sscanf(serialInBuffer,"%f,%f,%f",&x,&y,&z) == 3) { // managed to read all 3 values
      inputs[0] = x;
      inputs[1] = y;
      inputs[2] = z;
      newData = true;
    }
    serialCount = 0; // reset the buffer
   } else {
    serialInBuffer[serialCount] = byteIn;            // store the character
    if (serialCount<32)                                      // increase the counter.
      serialCount++;
  }
 }
}

main () {
  pc.attach(&onSerialRx);
  
  while (true) {
    if (newData){  
      newData = false;
      pc.printf("Got %.3f, %.3f, %.3f\n\r",inputs[0],inputs[1],inputs[2]);
    }

    // other stuff (nothing that will take longer than the time between serial messages)

  }

}