TESEO LIV3F: Antenna RF path

[vin883]

Hi,

I just designed a pcb with LIV3F module. I tried to follow layout instructions but I'm not RF expert. I can read through the USART bus but every values (GPGGA, GPVTG, etc.) are set to 0, as if there is no input RF signal. 

Herein below schematic design and my Eagle files, hope someone could point out what mistake I did?

[vin883]

Uart catch from module looks like this:

$GPGGA,000107.000,0000.00000,N,00000.00000,E,0,00,99.0,10

[GalaxyQuest]

Hi,

Some basic questions before we dig a bit deeper,

Can you please check if there is voltage on the LNA?

More of a fundamental question, are you testing this outside? 

Can you also show us what is xxGSV message is looking like?

[vin883]

Hi GalaxyQuest,

Thanks for your reply!

I tested inside and outside, same result.

VCC_RF and ANT_OFF got 3.3V, at least on pcb traces and pads, couldn't test on LNA pins itself since package is so small (BGA).

Well, I have no xxGSV (GPGSV, GLGSV, GAGSV, PQGSV) messages at all!

Only GPGGA, GNGSA, GPGGL, GPVTG, GPRMC...

[GalaxyQuest]

Hi,

Looking at the antenna datasheet, could you confirm if you have followed the guidelines mentioned in page.2 of the attached document -  the antenna datasheet. 

Eg: there are ground vias between the antenna and the edge of the board.

You can enable GSV messages in the register settings by the following command,

$PSTMSETPAR,1201, 0x80000,1

$PSTMSAVEPAR

$PSTMSRR

[vin883]

Hi,

There are indeed ground vias between the chip antenna and the board's edge (see below)

Il also tried replacing ceramic antenna by patch and screw mount SMA antennas with no effect...

Thanks for the instructions, I will try enabling GSV messages,

[vin883]

Hi,

I also tried with an active antenna directly tied to LIV3F RF_IN with no effect. So maybe it's a software issue? I previously worked with a X-NUCLEO-GNSS1A1 kit, which by default outputted every NMEA frames...

BTW, I tried enabling GSV messages, commands seem to be acknowledged (see below), but no xxGSV messages are showing up

[vin883]

Hi, to be sure on the RF issue or not, I tied all RF components from a X-NUCLEO-GNSS1A1 evaluation board to my custom board. So RF path from eval board is feeding the RFin of my custom board. 

The 2 boards are running simultaneously. Eval boards frames are correct, custom board's are not. So we can tell it is not an RF path design issue, right?

(compared logs below)

*********************** From X-NUCLEO-GNSS1A1

$GPRMC,094355.000,V,3733.09485,N,01417.88001,E,0.0,0.0,121222,,,N*7E
$GPGGA,094355.000,3733.09485,N,01417.88001,E,0,00,99.0,760.94,M,0.0,M,,*69
$GPVTG,0.0,T,,M,0.0,N,0.0,K,N*02
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GPGSV,1,1,02,14,29,160,,22,15,173,,,,,,,,,*73
$GPGLL,3733.09485,N,01417.88001,E,094355.000,V,N*49
$PSTMCPU,23.55,-1,49*4E
$GPRMC,094356.000,V,3733.09485,N,01417.88001,E,0.0,0.0,121222,,,N*7D
$GPGGA,094356.000,3733.09485,N,01417.88001,E,0,00,99.0,760.94,M,0.0,M,,*6A
$GPVTG,0.0,T,,M,0.0,N,0.0,K,N*02
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GPGSV,1,1,02,14,29,160,,22,15,173,,,,,,,,,*73
$GPGLL,3733.09485,N,01417.88001,E,094356.000,V,N*4A
$PSTMCPU,19.61,-1,49*40

**************************** From custom board

$GPRMC,000507.000,V,0000.00000,N,00000.00000,E,0.0,0.0,030917,,,N*78
$GPGGA,000507.000,0000.00000,N,00000.00000,E,0,00,99.0,100.00,M,0.0,M,,*6E
$GPVTG,0.0,T,,M,0.0,N,0.0,K,N*02
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GPGLL,0000.00000,N,00000.00000,E,000507.000,V,N*43
$PSTMCPU,30.61,-1,49*4B
$GPRMC,000508.000,V,0000.00000,N,00000.00000,E,0.0,0.0,030917,,,N*77
$GPGGA,000508.000,0000.00000,N,00000.00000,E,0,00,99.0,100.00,M,0.0,M,,*61
$GPVTG,0.0,T,,M,0.0,N,0.0,K,N*02
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GNGSA,A,1,,,,,,,,,,,,,99.0,99.0,99.0*1E
$GPGLL,0000.00000,N,00000.00000,E,000508.000,V,N*4C
$PSTMCPU,19.23,-1,49*46

[GalaxyQuest]

Hi Vincent,

Are you connecting RF-IN path from EVAL board directly to the RF_IN pin?

Just based on what you wrote, it does not seem that way.

Could you please check status of RESET pin, I hope it is a steady high and not toggling?

[vin883]

Are you connecting RF-IN path from EVAL board directly to the RF_IN pin?

Yes I did! 

Concerning Reset Pin, it was left floating. I did connect it to 3.3V to give it a try but did not change anything.