www.arrow.com

[JZela]

Hello,

I had recently purchased the TESEO-LIV3F GPS module from Arrow electronics.

https://www.arrow.com/en/products/teseo-liv3f/stmicroelectronics

 I have read the datasheet carefully before purchasing this module and appeared to be very similar to the Ublox Max 7c module. The pin outs were the same and performance and application appeared the same so I ordered ONE to test.

I build small GPS tracking circuits using either Ublox Max7 c or a more generic types such as these - 

https://www.aliexpress.com/item/GP-02-GPRS-Series-GPS-BDS-Compass-ATGM336H-Satellite-Positioning-Timing-Module-GP02-PCB-IOT-Artificial/32831293547.html?spm=a2g0s.9042311.0.0.13394c4dFIl0xu

So far,these modules work perfeclty in my circuit but now wondering what is different about the TESEO-LIV3F ?

I am using same voltage ratings (3.3v) in this circuit well within the operating specs.I have 1PPS on time pulse according to my Logic Probe,but not holding the circuit in proper time if at all.I am very frustrated and have been trying many things around the circuit.My circuit designs are always the same identical builds and never had an issue until applying this particular GPS MODULE.So my question is basically...is this TESEO-LIV3F compatible to replace the other GPS modules I have mentioned? If not,can I do something different to get it working properly? Your reply will save me a lot of time if I can find a solution to this issue.

Thank you.

Jim

[Karim RAMSI]

​Hello Jim,

Are you using the same board for all parts you mentioned?

If yes, allow me some comments:

Teseo-Liv3F embeds flash memory and TCXO and support Galileo, Beidou and QZSS.

Teseo-LIV3F doesn't embed LNA and Saw filter you need to add them to increase the sensitivity to -163dBm (intrinsic sensitivity is -158dBm without LNA and SAW filter is needed only in case of coexistence with other RF communication like BT, Wifi, etc ...)

RF input of Teseo-LIV3F is matched to 50ohm (direct connection to antenna).

In case you need to achieve -163dBm, please refer to following link, where you can find datasheet, schematic and BOM as well as the layout rules)

https://www.st.com/content/ccc/resource/technical/document/user_manual/group0/a5/d6/03/c4/b2/26/46/d4/DM00399112/files/DM00399112.pdf/jcr:content/translations/en.DM00399112.pdf

Hope it helps.

For more information and support you can contact me on karim.ramsi@st.com.

Kind regards

Karim

[JZela]

I was looking at the datasheet and did see the additional filtering at VCC and suggest I use this for this module.

The other GPS do not require these additional components and must be what is happening here as why it is not working,or not well.

The circuit does use an Si5351 RF chip and first suspected some sort of RFI interacting with the Tesio causing this to malfunction.I have had this occur using Ublox but was resolved by using 1 uf caps on VCC to voltage regulator V+/GND which resolved the issue.Going to dig up some things and try this mthod that you mention as well as in the datasheet.

Thanks for the info.

Just to be clear...we are referring to FIGURE 5 in the manual ?

Jim

[Karim RAMSI]

​Thanks for the feedback.

Yes I am referring to figure 5 and also figure 12 with schematic.

Best regards

Karim

[JZela]

So looking at my PCB schematic,I do not use this filtering at all. Also...my antenna is simply a 45mm length of wire directly connected to PCB from Pin 11.

Notice I do not have Pin 6 connected...I may also connect that to VCC like figure 12 is showing.

I need to find proper cap/choke values yet. Not sure if I need the additional circuitry for antenna? Looks I will need to reinvent the PCB to use this module.

For only 4 bucks each,maybe easier and wise to just use the Chinese modules I have been using that work fine on my existing PCB. Not saying the Tesio is a bad module,just not feasible for my current design and purpose.Just an FYI... I build and float these small circuits around the earth on balloons which are tracked using a network already in place. But since I already have this module,will see about using it for my test gear in which I can use a GPS for it anyhow.

Thank you for all the help pointing these things out...saved me a lot of time.

https://www.qrp-labs.com/flights/u3s22.html

Jim

[Karim RAMSI]

Hi Jim,

VBAT is the supply for the low power domain backup: backup RAM and RTC.

VCC-IO can be connected to VCC easily ( via wire).

In term of precision and accuracy and multi constellation, Teseo-Liv3F is the best in the market.

If you use it on Balloons, altitude accuracy of Teseo-Liv3f is the also the best.

Any feedback when using our solution is more than appreciated.

Best regards

Karim

[JZela]

Karim,

Here is the part I can not understand.

When the GPS arrived,I could clearly see it was of very good quality just in physical appearance. Like Ublox or the Generic modules,I simply placed it onto PCB and soldered it into the existing circuit.From there,I power the system up for a test run.This module was working and I allowed it to run for several hours.I noticed the Tesio was far more stable than the other GPS modules I use,including the Ublox.Speed and altitude was far more stable when it was sitting still where the others sometimes showed speeds and altitude variations.So I did see a much more stable operation from this module. I then assembled the solar cells and casing that holds the payload together...when I tested it during a sunny day,it would not power up at all.After checking connections...etc,had to dismantle everything so as I could diagnose why suddenly it was no longer working.Since...I can not get the GPS to do anything or lock signals.A few days ago I removed this module from my tracking PC and re-soldered to a blank PCB where I can focus on GPS only.At one point,it seemed to start working using the U-Center software and my FTDI interface...but was not getting a FIX. I felt maybe a bad location so tried various other locations for better view to sky. I have not had any luck and actually does not even do that much anymore.

I wonder if the RFI messed up the firmware in the GPS module somehow ? Will goof around with it more and see if I an get it working.

Thank you again for the help.

Jim

[Francesco Virlinzi]

Hi

In the module @ https://www.aliexpress.com/item/GP-02-GPRS-Series-GPS-BDS-Compass-ATGM336H-Satellite-Positioning-Timing-Module-GP02-PCB-IOT-Artificial/32831293547.html?spm=a2g0s.9042311.0.0.13394c4dFIl0xu

the pins#7 is declare 'NC' while for Teseo-LIV3F it is the VCC_IO this means 3.3V has to be there to guarantee a correct IO managements.

> I wonder if the RFI messed up the firmware 

What do you mean with "RFI"?

Do you have PPS blinking and NMEA stream?

What do you read in a generic $GPGSV message? (in details the CN0 fields)

Thanks

Regards

Francesco

[JZela]

When I say RFI this is because the circuit the GPS is mounted to also has an Si5351 chip onboard that sends the RF to be received by radio.In the past,I had issues with 5351 and GPS interfering with each other and learned I needed to isolate this RF using 1uf caps on the power supply to each component...mainly at the regulator which is a SOT23 type 3.3v LDO. Once these caps were installed,everything worked perfectly and have been doing this ever since.However,I am not at all familiar with this GPS module and just a thought,it mat react differently to RFI from the Si5351 chip.Like i mentioned,it was working when first assembled,then when it was sealed and ready to fly,it was tested in real time using solar power and stopped working altogether.Now,disassembled, I am now testing this GPS on a PCB all by itself using FTDI method into U-CENTER software.It started to work and was getting satellites,but no FIX...now ,I do not even get that much from it.It may now be damaged after all the soldering / desoldering. No big deal...I have bought replacements and will mess around with it after I get the main project finished.Like I said,this was a test run GPS since it was readily available from Arrow which ships free over night and was convenient for me as back up.I was hoping this module was like the others and drop in,solder and done...not the case.

Jim