STA8089 GA - Cannot activate IF pins to verify front-end functionality

[Armin Choopani]

I hope you have a great day

I’m Armin Choopani, Studying Electrical Engineering. I’ve been assigned a project which is setting up GNSS module. I decided to use the STA8089 GA IC. I’ve designed a matching circuit for its LNA pin. But Unfortunately I cannot verify its functionality (Front-end gain and NF), because I cannot find appropriate command to activate IF pins. I’ve read all NMEA file. But there wasn’t any command related to IF pins. I was wondering if you could help me to find this command. This problem halted my whole project, because I cannot verify anything.

Thank you all

[Francesco Virlinzi]

Ciao Armin

Which IC are you using? STA8090 is not enough.

ST provides:

• STA8090WG (WLCSP)
• STA8090FG (BGA)
• STA8090EXG (bigger BGA)

I don't understand what you mean with ' I cannot find appropriate command to activate IF pins'.

IF pins is always but to check the quality of your external RF-path you should have a 'GPS simulator'.

It's a tool which provide a well defined satellite signal with a constant fixed power with this signal you can test the RF-path using the NMEA command '$PSTMFRTESTON' which reports information only on one satellite (the same you programmed on the GPS-Simulator) and where you can check the CN0.

Just some question:

• who give you access on a Teseo IC?
• why not using a Teseo-LIV3F which is much more easy to use?

Thanks

Regards

Francesco

[Armin Choopani]

Thanks for your kind response Francesco

First of all, the project, which is a university-industry project, was given to me by my professor and he give me some data on it. Second, honestly speaking, I don't know what is Teseo-LIV3F. On the other hand my professor suggested me to use this IC (the IC I used is STA8089 GA not 8090, excuse me). By the way, I use a GSG-5 Series multi-function GNSS simulator with the power of -100 dBm (satellite ID-007). Also I used a differential to single ended amplifier to see the IF output but nothing was shown on the spectrum analyzer. On "pin by pin guideline" that I have, it is mentioned that "To enable the analog signal output a software command is required (refer to NMEA commands document)" but nothing is mentioned in NMEA file. You said "IF pins is always", you mean IF pins is always on and no software command is necessary?

Sincerely

Armin

[Francesco Virlinzi]

Ciao Armin

Teseo-LIV3F is the module ST presented in the market few weeks go:

https://www.st.com/content/st_com/en/products/positioning/gnss-modules/teseo-liv3f.html

it's designed to be easy to use.

On STA8089GA it's a QFN Automotive grade.

Just a question

Are you planning an external SQI flash? If so you could plan the STA8089FG which has an internal flash and ... less work for you;-)

While if you don't want any SQI-flash (internal or external) you have to 'enable' one of the configuration internally to the chip.

This is possible setting 4 gpios (boot0, boot1, boot2, boot3) in predefined configuration (using just some small pull-up or pull-down resistor in some pins)

Based the configuration you select you will use UART-0 or UART-2, board-rate etc....

The NMEA commands to test the RF-Path is "$PSTMRFTESTON" have a look @ https://www.st.com/resource/en/user_manual/dm00495927.pdf

In attach a reference schematic for STA8089GA, it should help.

Regards

Francesco

[Armin Choopani]

Grazie Francesco

I used an external flash (Winbond, W25Q16JBSNIQ).

Also I used same schematic you sent. As you said, I used a GPS simulatorThe spectrum Output is shown below

As you see, there is no signal around 4MHz (IF frequency). There is just a signal around 16MHz and its harmonics which I don't know where they come from! maybe leakage from PPS. But sometimes the satellite 7 is shown on the software and sometimes not.

And something more strange is the CPU usage which never goes further 10 percent (even when the IC detect satellite 7)

As you see something goes wrong in my test bench which I cannot find. I used $PSTMRFTESTON but again nothing was shown at the output of IF pins. Also the differential to single ended structure I used is attached.

I have tried different commands of NMEA but again nothing interesting happened. I don't know what should I do anymore!

I hope you don't get confused with lots of pictures which I attached =)

Best regards

Armin

[Francesco Virlinzi]

Ciao Amir

I assume you programmed the external flash with a Teseo-Binary and you are now running from flash.

The commands as reported in the manual:

"The GPS engine will restart in the RF test modality. This RF test forces the GPS to acquire the process only on the provided satellite’s id"

Sorry but in your schematic the signal coming from antenna (or simulator) has to go in the pad 'LNA_IN'

TP_IF_N and TP_IF_P are for internal usage (left not connected in the schematic)

With the PSTMRFTESTON you can evaluate the CN0 of a specific satellite which gives you a feedback of RF-path performance.

Regards

Francesco

[Armin Choopani]

Dear Francesco

1-Yes your assumption is true.

2- In pin by pin guideline it is mentioned |"Pins 5 and 6: TP_IF_P and TP_IF_N: These pins are used only for debug purpose. We suggest to bring out them only for

the first board release ensuring the possibility to check the RF and IF chain (on the RF section) in case of issues. To enable the analog signal output a software command is required (refer to NMEA commands document). An external Differential to single ended output buffer should be needed to interface the system to Spectrum Analyzer. Without these two outputs it is not possible to measure the overall RF/IF Noise Figure for debug and RF matching."

I used IF pins to determine Front-end functionality!

3-The signal coming from Antenna goes to LNA_IN pad (after a SAW filter) in my design too.

Another question. I set the CN0 of the GPS simulator 40dB/Hz. By using PSTMRFTESTON on satellite 7 sometimes I receive 36dB-Hz and sometimes nothing without doing anything.

Do you have any idea why this happens?

Also when I connect antenna nothing is received, even not a satellite.

Best regards

Armin

[Francesco Virlinzi]

Ciao Armin

Just a question: which binary did you install in the flash-memory?

The installed binary has to be in-line with the TCXO frequency you are using.

You can select the correct binary version based on the file name:

• xxxx_BOOT26 for TCXO 26MHz
• xxxx_BOOT48 for TCXO 48MHz

etc.

Ciao

Francesco

[Armin Choopani]

Hi Francesco

The "STA8089_4_5_10_BOOT26" is installed in the flash-memory and the TCXO frequency is 26MHz too (I use $PSTMGETPAR,1245 and the result is PSTMSETPAR,1245, 0X00000000*51 which means 26MHz TCXO).

But when I use $PSTMGETSWVER command, I get a weird answer.

I don't understand why the IC sends back STA8090 (as I said the IC I used is STA8089 GA).

Best Regards

Armin

[Francesco Virlinzi]

Ciao Armin

Sorry I had a busy week.

Looking your reports:

> STA8089_4_5_10_BOOT26 -> OK

> which means 26MHz TCXO -> Perfect

This means the binary and the HW-configuration are aligned.

On "STA8090_...622c..." isn't an issue, STA8090 and STA8089 are both Teseo_3, they sit on the same wafer ... they have only package difference.

Do you have still satellites issue?

Thanks

Ciao

Francesco