Firmware slowdown/halt on long-running Tessel 2

[lastbestmatt]

The Setup

I some Tessel 2s running an app that does three things:

• Read an I2C temperature sensor attached to Port B every 2 seconds
• Host an Express web server that serves the temperature reading in JSON format
• Blink LED 2 and 3 back and forth as a visual status indicator.

The Tessels are connected by wifi to an access point. They are set up with a static IP address on the local network. Another computer on the network does an HTTP GET on each Tessel every five minutes to read the temperature.

The Problem

Two Tessels have been running this way for 3+ months with no issues. However, a third one, with exactly the same software, seems to run for only 1-2 weeks before quitting. A power cycle will bring it back, but it will then quit again after a week or two. I have replaced this board with a brand new one, running the same software, but it showed the same problem.

When I say "quit," I mean that the app either stops running, or the whole board slows down so much that it's unresponsive (my blinking status lights stop, and the HTTP GET requests timeout). I don't think the firmware crashes, because I can occasionally still ping it (maybe 1/100 succeed). I am not able to SSH into the board in this state.

The only difference I can think of between the three boards is that the one that quits is located furthest from the access point, and has the weakest wifi signal strength. It's not terrible, just worse than the other two, and network connectivity to it seems fine after a reboot. The fact that a replacement board in the same location showed the same type of failure is suspicious.

Ideas?

Any ideas on where to look to troubleshoot this? Inability to SSH and the long time before failure makes it tough. Starting the project, I wasn't sure what to expect regarding how long I could realistically run these, but I've had great results with a few of the boards.

Is there any sort of watchdog functionality on the Tessel 2 that could reset it if an app crashes? If not, I've considered periodically running a Tessel.reboot() to see if that helps - but I'd hate to do that without looking for a better solution.

Thanks much.

[huseyinkozan]

Try https://github.com/huseyinkozan/tessel-network-example#debug ?