Avrdude: Ser_Open(): Can't Open Device "/Dev/Ttyacm0": Device or Resource Busy

avrdude: ser_open(): can't open device /dev/ttyACM0: Device or resource busy

you first need to make sure you have the correct read/write rights, as described here, esentially enter following commands:

$ sudo adduser <username> dialout
$ sudo chmod a+rw /dev/ttyACM0

the '/dev/ttyACM0' is the port your arduino is connected to, it should be listed in the /dev folder of your root.

second: after you have identified which port the arduino is connected to and you have set the correct rights for this port, you need to run following command. I am not sure what it does, I am not sure if it's really needed, but it made the uploads work for me on several occasions

$ sudo udevadm trigger

found this command here: http://starter-kit.nettigo.eu/2015/serial-port-busy-for-avrdude-on-ubuntu-with-arduino-leonardo-eth/

and third, you will find the upload sometimes a challenge of timing and luck. Keep pressing the reset (sometimes twice very consecutively) and meanwhile press the upload button of your arduino sketch. At certain moment, it will work. I had more luck when constantly changing small pieces in the code, so when I pushed 'upload', it had to compile the code first.

https://www.arduino.cc/en/Guide/Troubleshooting#upload

on some computers, you may need to push teh reset button

I have never messed with the bootloader, nor with ICSP pins and such (luckily)

Also have a look on the Arduino forum
or on the link provide by yourself

Kill process that raises Device or resource busy: '/dev/ttyUSB0'?

You can use

$ fuser /dev/ttyUSB0

to list the PIDs of the processes using the file. Alternatively, if your fuser command supports it you can use the -k option to kill them.

Could not open port error immediately after plugging in Arduino on Arch Linux

ModemManager might be the cause of your troubles. Try disabling it with, e.g. pkill -STOP ModemManager (continue the process with -CONT).

ModemManager is a (fantastic) piece of software that makes your 3G dongles work automagically. Because the Arduino appears as a serial modem, ModemManager tries to take control over it.

You can stop ModemManager from doing that by attaching a certain variable to your device. See the documentation for details. Essentially, create a udev rule, e.g. /etc/udev/rules.d/99-ttyacms.rules with the following content:


ATTRS{idVendor}=="0ca6" ATTRS{idProduct}=="a050", ENV{ID_MM_DEVICE_IGNORE}="1


Of course, you need to use your IDs. Use lsusb to find those values.

After you have created this file, reload udev with something like sudo udevadm control --reload-rules

Serial communication error between Arduino and Python

You can connect to your Arduino serial port from only one application at a time.
When you are connected to it via Serial port Monitor, Python couldn't connect to it.

You have two variants of solution:

1. Use serial sniffer instead of Arduino IDE's Serial Monitor. There are another answered question on this topic: https://unix.stackexchange.com/questions/12359/how-can-i-monitor-serial-port-traffic

2. Don't use any serial monitor, use Python! You can just continiualy read from serial, and print what have been received, something like this:

   import time, serial
   time.sleep(3)
   ser = serial.Serial('/dev/ttyACM0', 9600)
   # Write your data:
   ser.write(b'5')
   
   # Infinite loop to read data back:
   while True:
       try:
           # get the amount of bytes available at the input queue
           bytesToRead = ser.inWaiting() 
       if bytesToRead:
           # read the bytes and print it out:
           line = ser.read(bytesToRead) 
           print("Output: " + line.strip())
   except IOError:        
       raise IOError()
   

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