My first day with an Arduino MKR GSM 1400

I have a project in mind that needs internet connectivity but I won’t have access to WiFi so when I saw the Arduino MKR GSM 1400 with it’s GSM capability I thought I could use it to send my data over 3G.

Before I get to trying anything like that this is my experience using it for the first time.

Where do I put the SIM Card

I already had a SIM Card from GiffGaff to use I just needed somewhere to put it.

Spoiler alert: it’s on the bottom.

The bottom of the Arduino MKR 1400 with the SIM card slot on the right
The bottom of the Arduino MKR 1400 with the SIM card slot on the right

I was looking at the board still stuck in the soft foam and couldn’t for the life of me find the SIM card slot until I turned it over.

First Sketch

As you’d expect there is all the information you need to know about getting started on the Arduino website.

I followed the instructions and had the classic blink sketch up and running in seconds.

Second Sketch

I found a simple sketch that uses the GSM library to send a message. But that gave me the following warning

WARNING: library {0} claims to run on {1} architecture(s) and may be incompatible with your current board which runs on {2} architecture(s).

This was caused by including GSM.h rather than MKRGSM.h

From there I went to the MKRGSM Library page which has some useful examples including one to send an SMS message.

The sketch uploaded sucesfully but it got stuck on connecting.

I swapped the new SIM card for the one I use in my phone and that one worked. So I tried the new SIM card in a phone and it worked fine. I put the new SIM back into the Arduino and tried the sketch again, and still no joy using the new SIM card.

The top SIM does not work in the MKR 1400 but the bottom one does
The top SIM does not work in the MKR 1400 but the bottom one does

Going Forward

Overall the board was quick and easy to get going with. The hardest part is going to be figuring out why the SIM card isn’t working in it. Hopefully I can sort that and then get on with utilising the board in some projects.


18 thoughts on “My first day with an Arduino MKR GSM 1400”

  1. Hi,

    I am struggling to get MKRGSM working. Did you managed to figure out why one SIM is working and the other not?

    Did you have to attache any lipo battery or power form USB was enough to send SMS.

    Many thanks in advance,


  2. Hi Istvan,

    I haven’t figured out the SIM problem yet. I need to get more familiar with the functions available to the board so I can pinpoint where the problem is occuring. E.g. can it detect the SIM at all or is the problem when connecting to the network.

    So far I have just been using power via a USB cable.



  3. Ian did you figure it out? I am also struggling with getting the sim card to work.
    The program hangs on gsmAccess.begin(PINNUMBER)
    Thanks Jo

  4. Hi Jo,

    I haven’t had any proper time to look into it further.

    I did speak with a friend who gave a couple of suggestions which I’m yet to try

    1. Try putting the SIM in a phone and making a call to ensure it is completely active
    2. Is it because the SIM I have can be made into a Nano SIM and this is somehow stopping the connection from working

    What I really need to find a way of debugging is wether the SIM can be detected at all or is it being blocked at the network level.



  5. I’ve exactly the same problem : my nanoSim in a microSim adapter don’t work where it was working in my cell phone.
    I’ve tried with the phone of my wife that work with a real microSim and the MKDR GSM work since the first time !! Don’t understand.
    I’ll check deeper as soon I can.

  6. From the arduino specs

    During cellular transmissions, the peak current required by the board will exceed 500mA. This is in excess of what can be sourced by a standard USB port, so it is MANDATORY to have a 1500 mAh or higher LiPo battery plugged all the time, the current provided by the USB port will be supplemented by the battery. When powering the board using Vin, a 5V power supply that can supply at least 2A is required

  7. That is useful to know, although doesn’t quite explain why one sim card would work and not the other.

    When I get some time I’ll try both sim cards with the board powered by an external source.

  8. I’ve only tried two SIM cards. Both were from GiffGaff but only one of them worked in the Arduino board and that was the older one.

    If you find SIMs that work it would be great to hear which ones they are.

  9. Hi, Ian. Can we do not attach the antenna to MKR GSM? Is it possible to work?

  10. I had trouble the first time. It’s a bit fiddly and you just have to apply a bit of pressure to make it the antenna clip onto the board.

  11. Hi, i have a problem with a nano sim with adapter. I have two kinds of nano sim, but one works ok, and the other don´t work. I read Ian have same problem, who can solve it?

  12. Hi Ian! Not sure if you’ve revisited this project but I haven’t been able to get mine to connect, even after inserting my personal SIM card. However, I don’t have an antenna. Is that mandatory and if so, do you mind sending a link for the one you have? Thanks in advance.

  13. I never got one of the SIM cards working and as I had one that worked didn’t have the time to figure out the non-working one.

    I’ve always used an antenna which is the one that came with the board. Looks like you can get it from the Arduino store

  14. The only SIMs that I can get to work reliably in the 2 MKR GMS 1400 that I have are from Arduino and Things Mobile, but had one of the Things SIMs I was using be somewhat problematic, sometimes getEpoch() was 17 years slow and at other it would go cause the MKR go into a reboot loop. (Had the reboot loop with Vodafone too.)

    Thing support was responsive but not much help.

    The Arduino SIM would not send SMS to other networks and as I am using the MKR to work as an alarm for a 24/7 pump test and need to SMS mobile phones was not much use.

  15. Thanks for your input Martin.

    Sadly I haven’t used this board as much as I expected when I first got it but it’s still useful to hear other people’s experiences.

  16. I too have been struggling with the MKR GSM 1400.

    I have gotten it to connect a couple times, but they have seemed like a fluke. Mostly just using the ‘getting started’ sketch code that you can find places as well as the Example Sketch code that comes with library. Often it will just not connect or will hang.

    Has anyone had to set or fiddle with which bands are used? I can often switch the bands, but isn’t completely consistent and not really sure it is actually successfully setting it. Not sure I should be doing this in the first place either.

    Has anyone had any breakthroughs?

    – SIM provided by
    – I am using an antenna (that was sold with it)
    – I have a 2100mAh LiPo connected (and with the connector flipped around so that the ground wire is closest to the header)
    – I added a 300uF cap between Vcc and gnd
    – I can sometimes successfully run the GSMScanNetworks example sketch, but sometimes it [seemingly] hangs.

    Any thoughts? Thanks

  17. This board has been nothing but trouble for me. I was hoping for a small project to send a text message but have been struggling for about a month now. I finally got to send a sms when I switched to a Hollogram sim but my joy was short lived as now my MacBook Pro doesn’t seem to recognize the board any more. So frustrating!

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