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Trouble registering with LTE-M network on Hologram

Home Forums Other Questions Trouble registering with LTE-M network on Hologram

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This topic contains 7 replies, has 3 voices, and was last updated by  Adam Gold 2 days, 14 hours ago.

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  • #13170

    Adam Gold

    I’ve run into an issue registering our modems on the Hologram network (AT&T), and I wanted to see if anyone else using LTE-M has had the same issue or had possible fixes. We are using the Sodaq Ubee R410M with Hologram SIMs to send data from our Mayflys, and up the modems were working great when we pulled our stream gauges from the field two months ago.

    The modems appear to work like normal when I first connect to them using an Xbee explorer-type board and the M-Center program from Ublox (4 bars of service on the AT&T network, network status is “registered, roaming”, green LED indicating that the modem is on), but the modems are denied registration on the AT&T Hologram network when the modem is sent the command “AT+CREG?” to check the registration. Sending the modem the command to check the EPS registration, “AT+CEREG?”, returns “0, 5” indicating that it is registered, and the network status then switches back to “registered, roaming”.

    I’ve asked this question on the Hologram Community forum (no responses yet), but I wanted to see if anyone else was experiencing this problem using LTE-M.

  • #13171

    Sara Damiano

    Yes, I’ve seen this sort of thing.

    Well, not precisely, but similar. The Digi LTE XBee3’s have the same chip and I’ve seen it happen several times that the XBee refused to register, then I put it in bypass to check the registration, got it to register, then it magically stayed registered when I went back. I haven’t seen it consistently, though, just occasionally.

  • #13172

    Sara Damiano

    Do you have the latest u-blox firmware?

  • #13173

    Adam Gold

    Interesting, thanks for the reply! It’s odd that bypass mode works for the Xbees because the Sodaq Ubee I think is always talking directly to the Ublox.

    I don’t have the latest firmware update. I’ve gotten in touch with Ublox for help updating the firmware because it looks like some Hologram folks have had LTE-M issues that have been resolved by an update, although a Hologram engineer said that my issues likely weren’t related and asked me to make a new thread.

    Have you had success updating any Sodaq Ubee firmware? I think my only option is using AT commands to update and so far that has been unsuccessful.

  • #13180

    Sara Damiano

    I don’t have a uBee with the R410M, but I’ve updated a whole bunch of the Digi boards with the u-blox “Easy Flash” software and direct USB to the SARA chip. You should be able to use the same firmware and software to update. You may even be able to do the update through the serial port without soldering a USB connection on. (Sodaq breaks the pins out to J1, but that’s it.)

    You can get the most recent u-blox firmware and Easy Flash here: ftp://ftp1.digi.com/support/firmware/u-blox_EasyFlash_10.02_SARA-R410M-02B-01_IP.zip

    Are you still using ModularSensors or TinyGSM on your boards? I was thinking about it and remembered that TinyGSM had previously used “CEREG” to check registration but a while ago I changed it to “CREG” to query both EPS and GPRS registration to support 2G fallback on the R412 chip. That change might be why older code was having less trouble. I’ve modified TinyGSM (which ModularSensors uses) to use “CEREG” again – so that may help.

    These 4G chips just seem to be so much more finicky about connecting than the 2G ones were. I don’t know how much of it is the u-blox chip vs the SIMCom (SIM800) that we used to use in the GPRSBee and how much is the network itself, but I miss having 2G service.

  • #13223

    Adam Gold

    Thanks, @srgdamiano! I think that the “CEREG” change helped with the registration issue. I’m still not able to get ModularSensors 0.23.16 up and running, though. Seems like another modem issue – these things are definitely finicky! I’ll reach out through the SARA R410M modem GitHub thread or email. Thanks again for your help!

  • #13224


    Adam, Maybe give ModularSensors 0.23.11 a try. See https://www.envirodiy.org/topic/response-code-504-sending-data-to-data-envirodiy-org/
    It’s kind of working for me and Dan. Currently though I’m getting exactly 24 hour gaps in my data stream to MMW.

  • #13225

    Adam Gold

    Hi Brian, I wasn’t able to get version 0.23.11 to work, but I think my issue is related to code for the Sodaq Ubee R410M modem that I’m using (and possibly PlatformIO). I do get a 504 sending error when running 0.22.6, though. Fortunately, I was able to get version 0.21.4 working great after I made a fresh PlatformIO project and manually installed 0.21.4

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