I observe a problem with a Boron which I don’t understand and I wanted to check whether someone else had the same/a similar issue.
My intention is to interface a Boron directly with a Xenon via their Serial1 ports. You may ask why, because they could communicate via the cloud or via mesh, but hear me out, please. In my use case, the Xenon is part of a mesh network for home automation/security. The mesh itself is connected via a Xenon gateway (using ethernet) to my ADSL ISP and hosts a user interface and status dashboard via the Blynk platform. As a sort of backup solution, e.g. when my regular DSL is down for some reason, I would like to add a Boron, which, via its cellular connection and another Blynk dashboard, would give me remote access to my system. Since multiple gateways are not (yet) possible, my workaround is such that the Boron provides my user interface and sends commands via the serial connection to the mesh-connected Xenon which then forwards the appropriate command within the mesh.
Now the problem: I have the two devices connected to one another by crossing over the TX and RX pins (TX Xenon to RX Boron and TX Boron to RX Xenon), both have a common ground connection, both have their battery connected and charged, the Boron is also charging via the USB port.
If I only connect the TX Boron to RX Xenon, i.e. a one-way communication from the Boron to the Xenon, the system works, i.e. the Mesh receives input via Blynk running on the Boron. However, as soon as I connect the TX Xenon to the RX Boron (in order to receive also status information from the Mesh), the Boron gives me a red SOS flashing pattern followed by 1 flash indicating “Hard fault” (whatever that means) which is followed, after a couple of seconds, by a restart. The restart seems to execute correct but after a short moment the SOS flashing pattern returns and the cylce s (and this cycle continues endlessly).
Any idea what could be the problem here? Is it just a faulty RX pin on the Boron?