ATmega32u4 hung up? Linux still working fine.

Today when the coffee maker finished brewing a pot I didn’t get a text message! Not a complete surprise, last night I made some hardware changes and I’ve been around long enough to know I make mistakes.

However, I still had an SSH session open with the linux side of the Arduino, and an open telnet session (I monitor some parameters during the day so that I can know how to better my code). There was a distinct lack of data in the telnet session. I pressed Ctrl Z to end the telnet session, then typed “telnet localhost 6571” at the linux prompt to initiate the session. The telnet command was unsuccessful! So, I had an active SSH connection to linux, but I could not further telnet to get console info! I could still access the Yun over HTTP and SSH but it was like the Arduino code was not actually running.

It seems to me the ATmega32u4 was hung up somehow. What I did, to regain function, was simply use the Arduino IDE to reupload the sketch. I did this from my desk wirelessly. Everything is working again now. I probably could have walked to the kitchen and power cycled the Yun but I didn’t want to resort to that.

Comments? Thoughts?

I should add, last night I made 2 hardware changes. My shield is now powered by the ICSP header at 4.75V (better than the 4.4 on the 5V Pin!) Any I installed a multi turn potentiometer to tune my tone decoder.

EDIT: This issue was not seen in several days of operation prior to my recent hardware change.


@dankgus, it appears your telnet session was locked up from your sketch. You likely have a buffer overflow, or a boundary condition causing it. I would make a written record of this, and wait for the problem could repeat. Depending on your code & your daily activities, it could be months before this happens again.