Скачать или смотреть Why Does Your Arduino Reset When Checking the Serial Port in Python?

Discover the reason why your `Arduino` resets when using `serial.tools.list_ports` in Python and learn how to prevent it with a simple solution.
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This video is based on the question https://stackoverflow.com/q/63334161/ asked by the user 'M lab' ( https://stackoverflow.com/u/8452469/ ) and on the answer https://stackoverflow.com/a/63334728/ provided by the user 'Sourabh Choure' ( https://stackoverflow.com/u/8801846/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding Arduino Resets During Serial Port Check in Python

If you're working with an Arduino and trying to communicate with it via Python, you might have encountered a frustrating behavior: every time you check for serial ports using serial.tools.list_ports, your Arduino resets. This can disrupt your experimentation and development, so let's delve into why this happens and explore a solution.

The Cause: DTR Signal

What is DTR?

The DTR (Data Terminal Ready) signal is an electrical signal that helps in establishing a connection between the device and the serial port. When the DTR signal goes low, which means it's turned off, the Arduino resets. This reset occurs because the Arduino interprets the low signal as a command to restart.

Why It Happens in Python

When you use the Python module serial.tools.list_ports, checking for available serial ports often invokes a connection process that drops the DTR signal. This results in your Arduino resetting every time you attempt to scan for ports unless the port is actively being used in another program.

The Solution: Using a Resistor

Fortunately, there's a relatively simple solution to prevent your Arduino from resetting each time you check the serial ports. Here’s what you can do:

Connecting a Resistor

Components you need:

A 100 Ohm resistor

Jumper wires (if necessary)

Steps:

Identify the Pins: Locate the 5V and Reset pins on your Arduino.

Connect the Resistor: Attach one end of the 100 Ohm resistor to the 5V pin and the other end to the Reset pin.

Test the Setup: Now, run your code again to see if the reset problem persists when you check for your Arduino on the serial port.

Why This Works

By adding the resistor, you create a voltage divider that keeps the reset pin from being pulled low when the DTR signal changes. This way, your Arduino remains powered on and unaffected by the DTR signal while you are probing for ports.

Conclusion

In summary, it's common for an Arduino to reset when working with serial connections in Python due to the behavior of the DTR signal. By connecting a 100 Ohm resistor between the 5V and Reset pins, you can effectively prevent the reset, enabling a smoother development process. So, go ahead and make this simple adjustment for a hassle-free experience with your Arduino and Python!