I2c weirdness - notecard sending serial data when syncing (we use i2c)

When doing a hub.sync while connected to the notecard over i2c there is data being sent to our serial port. in this case /dev/ttyAMA0

How to stop this from happening? It’s disrupting our other communications.

Hi @cshannon - are you using a Notecard with the Notecarrier Pi HAT? If so, check the back of the Notecarrier as there is a SERIAL TXRX switch and make sure that is set to OFF.

No, we are not using the Pi Hat. We have our own board and there is no connection to the serial port on that. This seems like it is somewhere in the python notecard library? Meaning it is most likely a software issue because the notecard itself has no access to the serial port.

Hey @cshannon thanks for the additional detail. Can you share additional details about your custom board design, specifically which pins are connected to the Notecard and the like?

Also, can you share a sample of the program you’re running and the data you’re observing on the serial port?

We’ve not observed this behavior on any of our Notecarriers before and like to try to repro the issue on my end.

@cshannon I just had a random thought. Do you happen to know if the Notecard you are working with still has trace or watch enabled?

If you’re not sure, you can connect to the Notecard using the Notecard playground and send a manual {"req":"hub.sync"} request. if you see anything beyond an empty JSON object ({}) one of those modes is active and sending data over serial. You can turn trace off with t off and watch off with w.

Let me know if that sorts it before you spend the time sending along any of your design details or a code sample.

Sounds good @cshannon, do let me know if you see it again. If you do manage to replicate it, I’d be interested to hear if it happens for multiple Notecards (if you have others on hand), vs. a single device.

On Monday I will swap out this device for another one and see what I get.

1 Like