Go Down

Topic: Arduino Uno can't disable serial reset (Read 9 times) previous topic - next topic


I would like to disable the reset on serial communication on my Arduino Uno.

I follow the tips at : <thissite>/playground/Main/DisablingAutoResetOnSerialConnection

Doesn't work!

First I tried to disable the DTR reset in perl, see the end of the aformentioned page.  Does not work.  Maybe because I use Device::SerialPort under linux?

Then I tried the 120 ohm resistor trick as mentioned in the beginning of the page and that doesn't work either!

Are these issues well known?  Do these tricks only work on pre-Uno boards?  

What are my options now?  Removing the capacitor or SoftSerial?

Thanks for any help.  

James C4S

The Uno has a trace called "RESET-EN" that you can cut.  Then if you want to re-enable the auto-reset, you just solder bridge the connection back.
Capacitor Expert By Day, Enginerd by night.  ||  Personal Blog: www.baldengineer.com  || Electronics Tutorials for Beginners:  www.addohms.com


Then I tried the 120 ohm resistor trick as mentioned in the beginning of the page and that doesn't work either!

Actually that is an interesting question. The 8u2 usb chip might have a lot more ummpp from it's DTR signal to the 328 reset pin then the FTDI USB chip did. It would take someone owning both boards to experiment and see if it effectively defeats the auto-reset function on the Uno. I don't so I can't.



Jan 19, 2011, 08:50 pm Last Edit: Jan 19, 2011, 08:51 pm by DrRossi Reason: 1
I seem to have solved it for the moment by adding a capacitor between the reset pin and the ground.  I figured that with the resistor keeping the reset line up, the added capacitor maybe add enough oomph to keep the line up.

It did. I used 220 uF as it was the only one I had laying around, but I expect that a much smaller capacitor works as well.

Thanks for the responses.

Go Up

Quick Reply

With Quick-Reply you can write a post when viewing a topic without loading a new page. You can still use bulletin board code and smileys as you would in a normal post.

Warning: this topic has not been posted in for at least 120 days.
Unless you're sure you want to reply, please consider starting a new topic.

Note: this post will not display until it's been approved by a moderator.

shortcuts: alt+s submit/post or alt+p preview