Double precision floating point number. Has anyone else solved this problem? The reason that Serial.print(float) is able to print the floating point is because Arduino painfully and tediously implemented the Serial.print() function (the source code can be viewed at ArduinoCore-avr github page, it is almost like a hack) to support the floating point print. That is, the double implementation is exactly the same as the float… Arduino CNC Shield – 100% GRBL Compatable; Programming hundreds of Arduino Minions in one go; Can-Bus Breakout (Picking Can Bus over RS485) DIY Robot Arm by UFactory; Arduino Web Dashboard without the need of web-server; Arduino Float to String (That actually works) SparqEE CELLv1.0: Cellular made easy (Arduino/Pi/+) On the Uno and other ATMEGA based boards, this occupies 4 bytes. My motor controller has 4 pins that give a 0-5V output depending on the current the 4 motors draw (5V = 5A). Use the smallest applicable data type. Float and double are the same on AVRs - they aren't on the Due and some other fancier microcontrollers, but they are for AVRs. 5. To prove this point look at how many Arduino projects contain a delay(x00) in the loop; so if things go to slow simply decrease this number to release some CPU cycles ;-). Collect non-local data in structures whenever natural. Why not just send all four bytes of the float… 2. Compile with full size optimization. I could probably modify it if I just knew where 'rounding' is located. 3. Therefore you need 4 bytes in your array to store each float. The Arduino Reference text is licensed under a Creative Commons Attribution-Share Alike 3.0 License. If a non-local variable is only referenced within one function, it should be declared static. float is CPU/RAM intensive IMHO In many Arduino projects there is plenty of CPU/RAM left so I don't think this is a real issue. Eighteen Hints to Reduce Code Size 1. On the Arduino Uno (and other ATmega based boards) an int stores a 16-bit (2-byte) value. Use unsigned if applicable. You actually declared ax and ay as floats, so I made that change (to floats) in my source and still got a clean compile in a plain-vanilla Arduino IDE. This yields a range of -32,768 to 32,767 (minimum value of -2^15 and a maximum value of (2^15) - 1). Float has size of 4 bytes. I have a float variable with a value like -99,9 ... Debian,Mint,Ubuntu Arduino Mega 2560 Arduino Nano Arduino Duemilanove MAC OS Montain Lion Raspberry PI Model B. AWOL Guest; Re: Serial.write a float value #1 Jul 02, 2012, 06:45 pm. The monitor won't display more than 2 decimal places when reading a float var. So I wrote some code to sent the values to the serial monitor and I'm having some problems. Unless you ditch the whole Arduino part and go bare metal AVR with a C compiler, then the code is fine. 4. 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