a device you can use like tracker or node of CAT-M1/NB1/GSM

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following the line of the last project (square inch tracker) I come again with other tracker.

Global IoT Modem
Battery charger

I'm very in love with tracking devices and the solutions they can reach like never lose your pet (I have a cat) maybe track people or cars and the importance of these devices becoming smaller every day.

my goal with this project is

Use a combination of components like Modems and GPS modules connected to a MCU to send an accurate location to other device.

The specs are the follows

USB port to charge, power and communicate to the MCU

Battery charger

status led indicator

Modem LTE Cat M1/Cat NB1/EGPRS






Schematics for uTracker

Adobe Portable Document Format - 606.31 kB - 06/07/2019 at 16:54


  • back to the project

    Raúl Luna11/16/2019 at 18:36 0 comments

    Hi all!

    After a few days traveling Europe and very busy days in the office, Im back to this project, now I have everything I need to drive this piece of hardware to the end.

    I had some troubles with the pc so I lose the last firmware I write... need to write a new one

    with some luck I think I can make some test in field the next month.

  • GPS problem/solution

    Raúl Luna07/17/2019 at 17:34 0 comments

    Hello guys, in the latest tests on the GNSS I detected some problems due to poor signal, the position not always be accurate, I reviewed the pcb design and the schematics and at the first look everything looked like be ok.

    after a few hours I realized that I don't have any capacitors of 100pf on my components bags and the design needs a 100pf capacitor, so... what value are the capacitor that I placed on the pcb? I don't know jeje.

    Now I'm waiting for the arriving of that capacitors to test the GNSS again.

  • latitude, longitude

    Raúl Luna07/05/2019 at 00:52 0 comments

    Hi guys, today I finished the firmware layer who sends the data to the internet, I tested with a free account "cute cat" from CloudMQTT and now the broker is receiving the data of my actual location, latitude and longitude every 30 seconds.

    sorry about the image my cell phone camera is dying a little every day.

  • battery ok

    Raúl Luna06/29/2019 at 16:08 0 comments

    Almost forgot to test the battery management, I checked for the battery charge and operation over battery, seems to be ok but I need to test a little more, Im writing the adc code to read the voltage, I realize that I cant read a real value if the usb connector is plugged, I totally forgot to add a charger on/off feature to read the value no matter the state of the usb. I don't know how important is cuz the pins of the charger tell me every time the state "charging, standby, no battery" so, if you have the device plugged in we can know if the battery is full charged and when is unplugged the reads of the adc tell us if the battery are too low. 

    anyway... we are moving on and in the end I think we can have a functional device

  • Memory is working!

    Raúl Luna06/26/2019 at 22:17 0 comments

    after a few stumbles the data flash of the mcu is working, I defined only 100 bytes of space for the configuration and identification memory like apn, port, ip, serial number etc... all this memory are available for read and write from the user usb port.

    when I finish with this part I will write the code to assemble a chain of data and send every x minutes to a server (other modem connected to my pc).

    soon I will make some field test and then maybe a video.

  • The firmware

    Raúl Luna06/25/2019 at 21:28 0 comments

    right now I got working everything, last night I connect the uTracker with the GSM and CAT-M1 networks, unfortunately the NB-1 network are not available near to me so, nothing to do.

    the next step is write the application layer of the firmware, I don't really know how needs to work, I think the uTracker needs to have the feature to store data into the flash memory so I start for that.

    GNSS is working perfectly!

  • Its totally alive!

    Raúl Luna06/25/2019 at 01:07 0 comments

    after a few fixes due to my stupidity the uTracker is totally alive!.

    The first time, I could not make the usb work, the computer says I have a problem with the device, after a deep visual check I realized that I put a resistor instead of a capacitor in the ftdi, so I changed it and now works normally.

    Then... the Emulator don't recognized the target (MCU) I check again for some bad solder or something like that but i found nothing, I had to check the schematics and the pcb files and I found the problem...

    this area in the inner layers suppose to be a 3V3 area but I changed the clearance between  the holes and the copper layer and I did not realize that it was separated from the main area so the via hole is making contact with nothing.

    I fix this in the design but physically I had to solder a little wire between the pad and 3V3. 

  • The first one

    Raúl Luna06/24/2019 at 20:27 0 comments

    Ok, I finally finish of assemble the first uTracker and I think I'm a little more blind after solder 0402 size components.

    there is just a couple of capacitors and resistors missing but nothing important to test the major of features while that components arrive from the store.

  • the happiness box

    Raúl Luna06/21/2019 at 21:49 0 comments

    the pcb s just arrived to me.

    oh! man look at this beauty 

    I need to get all the components into a box and start to solder all of them, first I will solder the modem cuz he need a lot of heat and I don't want to de-solder other components in the process 

  • Almost here

    Raúl Luna06/19/2019 at 19:35 0 comments

    The PCB's almost here.

    next weekend will be very fun cuz I want to assembly a couple of PCB's, since I have to solder a lot of components I think I need go to the market and get a jar of soldering flux.

View all 16 project logs

Enjoy this project?



askhak wrote 10/20/2020 at 21:48 point

Did you finish the project?  Did you get the capacitors working? Looks really neat - nice small package

  Are you sure? yes | no

Raúl Luna wrote 03/19/2021 at 20:35 point

hey! I'm been a little away from here, but yes, project is working!

  Are you sure? yes | no

osman_korlu wrote 02/05/2020 at 19:20 point

hello I need a project like this 

A module using multiple eSIMs is required

to send and receive sms

can you help me

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Raúl Luna wrote 05/28/2020 at 19:16 point

Hello, last year I design a PCB  that can externally handle 2 sims by a mcu, shouldn't be a problem handle 2 or 3 more, please tell me more.

  Are you sure? yes | no

Trent Torkar wrote 06/13/2019 at 09:23 point

Looks good, have you assembled yet?

  Are you sure? yes | no

Raúl Luna wrote 06/19/2019 at 19:22 point

Thanks, I still waiting for the PCBs, I think they arrive to me by the weekend.

  Are you sure? yes | no

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