What are the causes of Arduino freeze

When working on a project using Arduino students come across a lot of problems and these problems can be either related to the Arduino code or to the Arduino board itself. Sometimes due to errors in the Arduino code that the compiler is unable to recognize or hardware problems the Arduino boards freeze completely and do not show any output. So, we have addressed some of the issues that cause the Arduino to freeze.

What are the common causes of Arduino freeze?

There can be multiple reasons that can cause Arduino to freeze or make it stop working so below are some of the common issues due to which Arduino freezes:

  • Running an infinite loop
  • Power voltage drop
  • Interruptus handling
  • Full memory utilization

Running an infinite loop

One of the main reasons for the freezing of Arduino is the Arduino gets stuck in the loop whose condition is always true and is unable to execute the other parts of the code. Though the “void loop()” section is in short, an infinite loop but this section itself contains loops and conditions but it does not run on any condition it simply executes the instructions given in it. To understand the concept of infinite loop you can see the code given below

int a = 0;

while(a == 5){

a = returnFive(); // will always return 5


In the above code we can see the loop will always be true always so it will keep on executing thus running an infinite loop and causing the Arduino to freeze.

To prevent Arduino getting stuck in the infinite loop avoid using while and for loop in the loop() section of the code if they take more time to execute.

Power voltage drop

The Arduino boards have operating voltage of 5 to 12 volts but if for some reason the voltage drops below 5 volts the Arduino will start to hang and will stop working. The voltage drop might occur because of the following reasons

  • Abrupt current drawn by any connected device
  • If connected in a standalone mode the battery might be low on charge
  • Too much noise in the supply voltage
  • Faulty USB cable or external power supply

To avoid such issues of voltage drop always check the battery connections and its charge in case of standalone mode. Also check the USB cable if used for powering the Arduino board and also check the devices connected with Arduino.

Interrupt handling

Interrupts can be the anomaly occurring while executing the Arduino code and whenever an interrupt occurs the Arduino stops the entire code and starts executing the instruction given for any possible interrupt. So, if the instruction for the respective interrupt is long or is taking considerable time then this can cause the Arduino to freeze.

Similarly, interrupts can be triggered accidently, by the ISR in the Arduino code and causes the Arduino to hang or freeze. To cater this issue, we can save the status of the interrupt in the registers of the microcontroller so I will prevent the accidental turning on of the interrupt.

We can minimize the processing time for handling the interrupt by optimizing the code for the interrupt handling and in this way the chance of freezing of Arduino can be minimized.

Full memory utilization

As we know that Arduino boards do not have big memory so it must be utilized effectively. However, in the case where the Arduino code is quite long and is using too many variables there is a chance that memory of the Arduino might get full and cause it to hang or reset.

Similarly, if we allocate large memory using malloc() function this can also cause the Arduino to fill up the memory of the Arduino. The compiler will also warn while compiling the code when the memory is near to full or is already full.

This issue can be avoided by doing the actions listed below:

  • Used only necessary variables
  • Avoid using the malloc() function or use free() function when using the malloc() function
  • Try to declare the variables inside the functions


The Arduino boards can show strange behaviors like getting freezed for a long period of time or resetting itself after some time. Such behavior is observed when there is either problem in the Arduino code or the board itself. We have listed some of the most common causes of Arduino freezing and also suggested some solutions to avoid such issues in this guide.

About the author

Aaliyan Javaid

I am an electrical engineer and a technical blogger. My keen interest in embedded systems has led me to write and share my knowledge about them.