Square Inch Tracker

A device that can send a position, u can use this for track people, pets, cars...

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actually no big description for this project.

Global IoT Modem, Global eSIM, GPS module, Microcontroller and passive components that make everything works.

for years I've been dreaming with make a mini tracker, but components like modems and GPS/GNSS was too big for that project, in the last square inch contest I just stayed watching because in that moment was impossible fit all components in just one square inch, now I have this new opportunity and I introduce to all of you my one square inch tracker. 

This device are very simple, everything starts when plug the usb,  at this time the device starts to charge a battery through the TP4056 thats are configured for charge at 450mA, at the same time the whole circuit is feeded and microcontroller are ready for work.

Microcontroller operate Modem and GPS module.

When you plug usb to your computer the FTDI create a VCP so you can communicate with the microcontroller through a terminal like hyperterminal, putty, docklight... the commands for the device are not created yet, the idea is configure the device for first time, telling him ip address, port etc...    

microcontroller knows the state of the battery(charging/standby), in the beginning the mcu could read battery voltage but I couldn't fits that in one square inch so...

well I think this is all about my device i hope some of you are interested on follow this project until the end and I have to thank you for come to see.

Adobe Portable Document Format - 411.48 kB - 08/23/2018 at 21:14


schematics Altium files

x-zip-compressed - 55.50 kB - 08/22/2018 at 20:25



Bill of materials

ms-excel - 33.50 kB - 08/12/2018 at 01:12


  • 3 × CC0603MRX5R7BB106 CAP CER 10UF 16V X5R 0603
  • 8 × CC0402KRX7R7BB104 CAP CER 0.1UF 16V X7R 0402

View all 35 components

  • The other wait

    Raúl Luna3 days ago 0 comments

    yesterday the PCB's arrive to me in the morning, today I finished the assembly of one square inch tracker, unfortunately the microcontroller and the USB connector still missing and just 8 days left to the deadline.

  • The very end of the long wait

    Raúl Luna4 days ago 0 comments

    I so happy, PCB arrives to me this morning

    and the NB1 modules from QUECTEL comes in the same box.

    take a look on this beauty

    need to assembly one, MCU and USB connector still missing so I hope get those components before deadline

  • the long wait

    Raúl Luna09/15/2018 at 00:35 0 comments

    my long wait for the PCBs and QUECTEL modules is about to end, I've been thinking about the deadlines and oh man! if deadlines had stayed on September 10th I would no chance to finish the project.

    It seems that the modules and pcb's just arrived to TX US and are in transit to MTY MX I'm very excited.

  • the firmware situation

    Raúl Luna08/20/2018 at 16:26 0 comments

    after consulting the firmware situation with my pillow, I decided start writing the code on a MCU of the same family (RL78G13) so when the device arrives to me, I just make a new project, copy the code and modify the files for inputs and outputs. 

    There only a few days left for this crazy and fun contest ends, so, I will write a test code very very basic but as functional as possible.

  • problems and solutions

    Raúl Luna08/19/2018 at 21:06 0 comments

    I had some problems to get the BC68 module from dealers in my country, fortunately I know some guys that works on QUECTEL and by the last 4 days I've been trying get the module directly from QUECTEL headquarters, finally they told me "OK we will send to you a module" Im so happy, the module heads to the PCB manufacturer and then comes to me.

    it's time to start thinking about the firmware.

  • PCB ready

    Raúl Luna08/14/2018 at 16:06 2 comments

    I finished routing, now the PCB is ready to be manufactured

  • Sunday

    Raúl Luna08/12/2018 at 15:11 0 comments

    today is sunday in my country and my girlfriend wants to see a movie, I'll be back, the PCB are almost ready for send to manufacturer.

  • hard times

    Raúl Luna08/11/2018 at 15:50 0 comments

    looks like everything fits in one square inch, but the pcb is not routed... yet

  • time of truth

    Raúl Luna08/10/2018 at 16:26 0 comments

    time to see if everything fit on one square inch

  • schematic time

    Raúl Luna08/10/2018 at 15:36 0 comments

    start to design schematics

View all 11 project logs

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Jan wrote 3 days ago point

Hi Raul!

Very interesting project. Do you have any info on power consumption, accuracy etc? Are you planning on summarizing those things in a log some day?

  Are you sure? yes | no

Raúl Luna wrote 3 days ago point

Hi Jan, I can made estimation about the power consumption in relation with the datasheets of the modules but I could make some mistake with some calculation and  the results can be different in a real measurement.

When all the missing components arrive to my lab the first thing to do for me are write a basic firmware, so, in that moment I can measure the power consumption in transmission and reception, standby, etc.

Right now, I can summarize things like accurate of the GPS/GNSS module and the freq of the modem because that information are available in the datasheets of the modules.

Thank You for your interest.

  Are you sure? yes | no

Nicolò wrote 09/02/2018 at 14:05 point

I searched a little on the internet but I did not understand how these eUICC work

They seem to be chips but I do not understand who sells them.

  Are you sure? yes | no

Raúl Luna wrote 09/02/2018 at 16:12 point

Hi Nicolò, eUICC (embedded universal circuit card) is not a form factor in hardware that is commonly mistaken, it refers to the fact that you can have more than one profile on your sim card, commonly normal sim cards have 64KB or 128KB of memory, this one have 512KB so you can host more than one profile, so, you can manage multiple mobile network operator subscriptions.

Usually the mobile network operators will not provide this (in my case on my country) but you can buy this sim card in gemalto or EMnify, they also provides to you the way to manage this profiles remotely.

I hope I've helped

  Are you sure? yes | no

Nicolò wrote 09/02/2018 at 19:46 point

But on your board you don't have a SIM tray or at least it seems not.
But that module must be connected to a SIM or something right?

  Are you sure? yes | no

Raúl Luna wrote 09/03/2018 at 01:16 point

yes, the module have a sim card connected, but this sim card is an embedded sim and is soldered to the pcb, if you see the sch files in the modem sheet you can see the "U5" component, that is the sim card.

  Are you sure? yes | no

Raúl Luna wrote 09/02/2018 at 16:26 point

I can see that you work on a project that involves a modem, if you want, I could join and help with the communication part I have years of experience in that area.

  Are you sure? yes | no

Nicolò wrote 09/02/2018 at 19:54 point

Yea, why not!
The project will be released as Open Source once done.
I'm a hobbyist, I learned all the electronics by myself.
Every little bit helps right now.

  Are you sure? yes | no

Raúl Luna wrote 09/03/2018 at 01:19 point

I just joined into your project

  Are you sure? yes | no

cyrexxx wrote 08/23/2018 at 21:04 point

I see you are having trouble with the printing port labels (going blank) in the Sch output.
there is an easy fix for this 
  go to DXP>> Preferences>>Schematic>>General>> disable - Render Text with GDI+

  Are you sure? yes | no

Raúl Luna wrote 08/23/2018 at 21:17 point

Thank you! I changed the files now are ok.

  Are you sure? yes | no

Phillip Scruggs wrote 08/20/2018 at 18:52 point

Great looking project. Ill need to look into Global IoT Modems more as I am only used to using a GSM modem/SIM card for projects.

  Are you sure? yes | no

Raúl Luna wrote 08/22/2018 at 14:52 point

in fact, is the same thing, a modem and sim card, but this modem is NB-IoT LTE based and works in a lot of frequencies making him a global module, the problem is that not all countries have this network, I live in MTY MX and I will cross the border into Texas for make the tests cuz in Mexico NB1 will not ready until the next year.

the sim card is an "eSIM / eUICC" that can manage a lot of profiles, usually a normal sim card have 64k or 128k this one have 512k and its form factor is an MFF2, so, we can connect with many operators, in my case I use EMnyfy sim card and establish connection with TELCEL and MOVISTAR in Mexico, AT & T, Virgin Mobile and T-Mobile in the USA.

Thank you for your interest, feel free to ask me about this

  Are you sure? yes | no

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