Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, an initiative of Stroud Water Research Center designed to help people advance knowledge and stewardship of fresh water.
New to EnviroDIY? Start here

Reply To: GPRSBee

Home Forums Mayfly Data Logger GPRSBee Reply To: GPRSBee


    After a sabbatical of several months, I’m now back working on the LTE-M XBee and I HAVE IT WORKING!

    For software, I’m using:
    – StreamDebugger
    – Parts of Diagnostics.ino
    – My own .ino

    My hardware is:
    – My XBee (Digi XBee3 Cellular Smart Modem XB3-C-A2-UT-001)
    – Mayfly 0.5b
    – Soldered SJ13
    – 3.7v Lipo battery
    – USB to Windows PC – no XCTU
    – Hologram SIM

    My network is AT&T, very weak signal in south Florida.

    Here are some items that helped me get over the hump:
    1. My XBee won’t communicate at any speeds higher than 9600 baud!

    2. I have to connect my battery AFTER I attach the USB to my PC. Otherwise the XBee won’t communicate at all.

    3. It takes anywhere from 6 to 20 minutes to connect to the network where I am. None of the software routines in the library that I’ve found will wait that long before starting over – creating an endless loop. The Hologram Dashboard showed that there was “some activity” every few hours, so I knew the XBee was trying. So I wrote my own code to give it more time and BINGO. I will see the dreaded “22” response to AT-AI (registering to network) for several minutes, then “25” (registration denied) for a while, then eventually “00” (connected).

    4. The next problem I found is either a timing bug in TinyGsmClientXBee.h or in some configuration that I don’t understand. In “modemConnect”, the code tries to determine the IP@ from a URL using the “LA” (Lookup Address). Unfortunately, the “OK” from the AT command precedes the IP@ in the serial response. The code ignores the IP@ and replies with IP@= I modified the stream.readStringUntil statement to keep looking for the address which solved the problem.

    5. Now that I have most things working I’m going to try to get the XBee to sleep, so far unsuccessfully. I can see that most of the time the XBee is using about 2ma when just connected to the network. But every minute it briefly does some activity that burns a lot more power. Any help on this would be greatly appreciated.

    I’d be happy to talk with anybody more about my experience.