Tag Archives: arduino

“error: cannot access /dev/ttyUSB0” Arduino (NodeMCU) esp8266

Question: Getting permission “error: cannot access /dev/ttyUSB0”
Answer: Just open terminal (Ctrl+Alt+T) and type this command and enter root password
$ sudo usermod -a -G dialout ${USER}

On Linux (Ubuntu), Arduino IDE will not be able to upload sketches (or communicate with the board at all) if you don’t change permissions on /dev/ttyUSB0 appropriately. Same as with the NodeMCU ESPlorer IDE, etc. Actually, this very problem comes up whenever you want to access a (virtual) Serial COM port on Linux.

It might happen that when you upload a sketch – after you have selected your board and serial port -, you get an error Error opening serial port … If you get this error, you need to set serial port permission.

Open Terminal and type:

$ ls -l /dev/ttyUSB*

you will get something like:

crw-rw---- 1 root dialout 188, 0 5 apr 23.01 ttyUSB0

The “0” at the end of USB might be a different number, or multiple entries might be returned. The data we need is “dialout” (is the group owner of the file).

Now we just need to add our user to the group:

$ sudo usermod -a -G dialout ${USER}

NOTE: where USER is NOT  your linux user name keep as it is.

In some cases, You will need to log out and log in again for this change to take effect.

Add NodeMCU ESP8266 to Arduino IDE

In this tutorial, we’ll learn how to program your NodeMCU or ESP8266 using an Arduino IDE. NodeMCU board is not available by default.

The NodeMCU ESP8266 is a low-cost WiFi module built by Espressif Systems. Its popularity has been growing among the hardware community thanks to its nice features and stability, to the point that it can be easily programmed using your Arduino IDE.


  1. Arduino IDE version 1.7 or higher
  2. Active Internet connection
  3. NodeMCU or ESP8266 board (for testing only)

Step 1: Adding ESP8266 URL to Arduino IDE Board Manger

  1. Make sure you are using Arduino IDE version 1.7 or higher.
  2. Add additional URL for board manager. Go to File >> Preferences and paste below url in Additional Board Manager URLs.                                                               http://arduino.esp8266.com/stable/package_esp8266com_index.json

JSON URL for ESP8266 in Arduino IDE

Note: Sometimes pakage_esp8266com_index.json link is down due to heavy download try again after few hours.

Step 2: Open Board Manager

  1. Go to Tools >> Boards >> Board Manager

Board Mnanger Link

Step 3: Search and Installing Node MCU (ESP8266) in Arduino IDE

  1. Type “ESP8266” in search box.
  2. Select ESP8266 Community. (If internet is not available then you will not find ESP8266)
  3. Click on Install Button. Download progress starts. wait for finish.
Install NodeMCU
Installing ESP8266

Step 4: Verify installation of ESP8266

  1. Go to Tools>>Boards>> select NodeMCU (If you don’t find NodeMCU, check your installation is ok)
  2. Select proper Com port
  3. Upload blink example and check is it working. on board LED uses GPIO2
NodeMCU board in Arduino IDE
NodeMCU board is visible

Additional Resources

  1. Installing ESP32 in Arduino IDE
  2. Getting Started with ESP8266
  3. ESP8266 IOs
  4. NodeMCU Pin Numbers and Confusions (Must read)




How to convert integer to string and string to int on Arduino ?

New version of arduino supports String data type . In this tutorial we will see both integer to string and string to integer conversion. Conversion of integer to string can be done using single line statement.

int a = 1234;
String myStr;
myStr = String(a);  //Converts integer to string

Continue reading How to convert integer to string and string to int on Arduino ?

Installing ESP32 Board in Arduino IDE on Ubuntu Linux

In this tutorial we are installing ESP32 board in Arduino IDE. Its not same as installing ESP8266. ESP32 is dual core CPU in arduino IDE it will not support all the functions but its enough to make many projects.

ESP32 is highly-integrated with in-built antenna switches, RF balun, power amplifier, low-noise receive amplifier, filters, and power management modules. ESP32 adds priceless functionality and versatility to your applications with minimal Printed Circuit Board (PCB) requirements. ESP32 can interface with other systems to provide Wi-Fi and Bluetooth functionality through its SPI / SDIO or I2C / UART interfaces. Continue reading Installing ESP32 Board in Arduino IDE on Ubuntu Linux