void setup() {
  char outStr[10];
  byte rxVal = 0;

  Serial.begin(115200);
  do {
    float voltage = (300.0 + rxVal) / 100.0;
    dtostrf(voltage, 6, 2, outStr); // as the volatage is x.dd and we want 6 positions, we will have 2 spaces in front of the value
    Serial.print("rxVal = "); Serial.print(rxVal);
    Serial.print("\tvoltage = "); Serial.print(voltage, 2); // printing the float with 2 decimal
    Serial.print("\t\tvoltage string = \""); Serial.print(outStr); // printing the string
    Serial.println("\"");
  } while (++rxVal != 0);
}


void loop() {}