How can I reset an Arduino board

Question

I ve uploaded a sketch to an Arduino Uno whose loop is something like this   void loop        Serial println  Hello  World         So  now  I can t upload anything anymore  because the IDE says  port already in use    Is there a way to  reset  the Arduino without another programmer   Nothing else is using the serial port  and everything went just fine until I uploaded the previous sketch   I ve found some interesting things    Problems with 0021 on Ubuntu 10 04 Lucid Lynx Re  Problems with 0021 on Ubuntu 10 04 Lucid Lynx Uno sending serial data becomes un-connectable to Serial Monitor

User · Answer

Arduino Leonardo board    Unplug the USB cable     Connect the RX Pin to ground  Plug in the USB cable Upload a new program    Remove the USB cable Remove the RX grounding

User · Answer

I also had your problem and I solved the problem using the following steps  though you may already finish the problem  it just shares for anyone who visit this page     Unplug your Arduino Prepare an empty setup and empty loop program Write a comment symbol      at the end of program Set your keyboard pointer next to the     symbol Plug your Arduino into the computer  wait until the Arduino is completely bootloaded and it will output  Hello  World   You will see the  Hello  World   outputting script will be shown as comment  so you can click Upload safely

User · Answer

I had the same problem on two Arduinos  one Uno  and one Modern Device Freeduino USB Host board  and the window between reset and the beginning of serial port usage was so small that it was impossible to upload     I finally fixed the problem by purchasing another Arduino Uno and building an ISP cable per these instructions  and using it to flash the Bare Bones app from the examples into each inaccessible board  using Arduino IDE version 0023  following these instructions  to change preferences txt   Be sure to save the original file before editing it so you can replace it after you ve rescued your Arduino    It took one quick upload to fix each board  Such a fast fix after so much grief  You might not want to purchase another Arduino  but consider these benefits    You can overwrite the bootloader on your Arduino to gain more space  Once the bootloader is overwritten  the board will boot faster  Supposedly you can program raw AVRs for special projects  but I have not tried this  Google for ArduinoISP It will quickly fix Arduinos that you block in the future  You can now safely experiment to find ways to prevent serial port usage from locking up the device in the future

User · Answer

I just spent the last five hours searching for a solution to this problem  serial port COM3 already in use and grayed out serial port    I tried everything every forum and Q amp A site I could find suggested  including this one      What finally fixed it  got rid of the last code I d input that got stuck and uploaded simple blink function    Follow this link -- http   arduino cc en guide windows and follow the instructions for installing the drivers  My driver was  already up to date   but following these steps fixed the glitch  I am now a happy camper once again   Note  Resetting the board manually with the button on the chip  or digitally through miscellaneous codes on the Internet did not work to fix this problem  because the signal was somehow blocked confused between my Arduino Uno and the port in my laptop  Updating the drivers is like a reset for the  serial port already in use  problem    At least so far

User · Answer

Make sure you plug the Arduino directly into the computer and not through a hub  Using a hub will give you this error

User · Answer

Here s what I did in Linux to be able to program my Arduino Micro which was stuck in a loop sending the 0 key when connected by USB     while true  do xinput float   xinput --list   grep -i Arduino   awk   print  7     cut -d    -f 2   done   Your output might be slightly different so just try running     watch xinput --list   then plug in the Arduino and see how the output is formatted   This stopped X from accepting the keypresses and allowed the Arduino IDE to program finally

User · Answer

Here is the best way that works out if you are trying to program through the USB cable    Ground the Tx signal on the board  connect digital I O  1 to GND  Plug the USB cable Upload a new program Remove the USB cable Remove Tx grounding   You are all set

User · Answer

If you still have the serial console open  it will reserve the serial port  Close it  and try again

User · Answer

If the port says Already used  then you are probably using the wrong port   Switch it to the port where you connected your Arduino and then try to re-upload  you will definitely see it work

User · Answer

If nothing helped then you should arrange one more board and try to flash it through the Arduino as ISP option as shown in Arduino as ISP and Arduino Bootloaders or From Arduino to a Microcontroller on a Breadboard   Instead of a boot loader  you can select your own programs to flash via ISP

User · Answer

Try the following    Prepare the basic empty program  empty setup  loop  etc   Compile it  Reset the Arduino using the hardware button on the chip Press Ctrl   U to upload your code  If unsuccessful - got to 3    There is a delay before the boot loader starts the programs  just work on your timing  It worked for me when a bug in my Arduino s code was executing a soft reset every 500 nbsp ms

User · Answer

Based on my experience with the communication already in use or blocked  I would say that the program you are interfacing with still has the communication open   I also found that if you disconnect the USB cable it will rest the communication  It is not the greatest solution  but it solves the problem

User · Answer

The only way it worked for me for arduino nano 33 iot is via pressing the reset button on the board continuously many time then press uoplad

User · Answer

For Arduino Y  n users  try uploading via Ethernet Wi-Fi  menu Tools  rarr  Port    I had exactly the same problem  and I tried pretty much everything  apart from burning a new bootloader   I am surprised it worked  but I ve uploaded an empty sketch without any problem

User · Answer

I got a similar problem   If I power on my Arduino  there is a delay before the uploaded program execute   So I use that delay for uploading new program  or empty program   void setup      void loop       So my problem was solved   Unplug any connection to Arduino pins before upload

User · Answer

I had this issue as well  I tried the above methods and none seemed to work  however something that did work  somehow  not sure if it was just a freak thing or it is actually a way to do it  was    Unplug USB from the Arduino Press and hold the reset button Plug in USB and power up Continue holding and upload the sketch  Once it s done uploading  release the reset button

User · Answer

After scratching my head about this problem  here is a very simple solution that works anytime    Unplug your USB cable Go in Device Manager Click on Ports  COM  amp  LPT  Right click on Arduino     COMx  Properties Port Settings Put Flow Control to HARDWARE Create an empty sketch  Optional  Connect the USB cable Upload  Ctrl   U         Empty sketch to fix the upload problem    Created by Eric Phenix    Nov 2014  void setup           The loop routine runs over and over again forever  void loop         delay 1000         Et voila

User · Answer

Unplug Tx from the microcontroller Insert USB cable Wait until full load Connect Rx with hardware Compile empty sketch in prosses and unconnect tx  don t worry about the error  Connect Rx with hardware Compile empty sketch Power off and connect Tx

User · Answer

I had the very same problem today  Here is a simple solution we found to solve this issue  thanks to Anghiara    Instead of loading your new code to the Arduino using the  upload button   the circle with the green arrow  in your screen  use your mouse to click  Sketch  and then  Upload    Please remember to add a delay   line to your code when working with Serial println   and loops  I learned my lesson the hard way

User · Answer

Be sure you are not accessing the serial port from a terminal  That loop  or any code  should not prevent the Arduino from being programmed

User · Answer

First of all  connect your Arduino device  Then go to Device Manager and uninstall the driver  Now remove your Arduino device  Again connect you Arduino device to your system  Now install your driver  which you have uninstalled earlier     It will free your port for sure

[serial-port] How can I "reset" an Arduino board?

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