GPS-RTK-SMA Breakout - ZED-F9P (Qwiic) doesn't provide GPS location data

GPS/GNSS Development Boards
1

Hey team,

We bought some GPS RTK Kits(https://www.sparkfun.com/products/18292) last July and they work very well. However we recently purchased another one RTK board(https://www.sparkfun.com/products/16481) and it seems not providing GPS location data.

Here is how I tested it, basically I have a Raspberry PI 4 Model B connects to the ZED-F9P board then connects to an antenna.

If using the ZED-F9P we purchased last year, it works fine, gives me the location data, however if using the recently purchased one, the location data is empty.

Below is the code snippet:

import sys

sys.path.insert(0, ‘./lib’)

import time

import serial

import pynmea2

ser = serial.Serial(

port=‘/dev/ttyACM0’,

baudrate=9600,

parity=serial.PARITY_NONE,

stopbits=serial.STOPBITS_ONE,

bytesize=serial.EIGHTBITS,

timeout=1)

while 1:

x=ser.readline()

print(‘start’)

print(x)

print(‘end’)

time.sleep(5)

Below is the working RTK output:

carlton@raspberrypi:~/gps $ python test.py

start

b’$GNRMC,015427.00,A,3343.15216,S,15057.70243,E,0.051,190723,A,V*04\r\n’

end

start

b’$GNVTG,T,M,0.051,N,0.094,K,A*34\r\n’

end

start

b’$GNGGA,015427.00,3343.15216,S,15057.70243,E,1,12,0.72,95.3,M,19.7,M,*6E\r\n’

end

start

b’$GNGSA,A,3,05,14,27,04,20,09,30,1.17,0.72,0.92,1*01\r\n’

end

start

b’$GNGSA,A,3,1.17,0.72,0.92,2*0B\r\n’

end

start

b’$GNGSA,A,3,05,30,03,02,08,1.17,0.72,0.92,3*05\r\n’

end

start

b’$GNGSA,A,3,24,21,09,33,16,14,1.17,0.72,0.92,4*03\r\n’

end

start

b’$GPGSV,2,1,07,04,16,035,15,05,13,237,21,09,46,025,21,14,51,295,29,1*68\r\n’

end

start

b’$GPGSV,2,2,07,20,16,267,28,27,11,141,13,30,59,209,27,1*5D\r\n’

end

start

b’$GPGSV,1,1,01,04,16,035,14,5*51\r\n’

end

start

b’$GPGSV,1,1,04,05,13,237,17,14,51,295,18,27,11,141,16,30,59,209,19,6*6C\r\n’

end

start

b’$GPGSV,2,1,06,02,01,066,07,61,140,08,37,116,13,07,222,0*6B\r\n’

end

start

b’$GPGSV,2,2,06,13,07,222,17,05,351,0*60\r\n’

end

start

b’$GLGSV,3,1,11,65,15,005,66,60,323,67,43,226,68,00,203,0*72\r\n’

end

start

b’$GLGSV,3,2,11,68,00,203,75,03,122,76,46,162,77,47,240,0*74\r\n’

end

start

b’$GLGSV,3,3,11,77,47,240,78,04,282,85,14,133,0*46\r\n’

end

Then here is the non-working output:

carlton@raspberrypi:~/gps $ python test.py

start

b’$GNRMC,V,N,V*37\r\n’

end

start

b’$GNVTG,N*2E\r\n’

end

start

b’$GNGGA,0,00,99.99,*56\r\n’

end

start

b’$GNGSA,A,1,99.99,99.99,99.99,1*33\r\n’

end

start

b’$GNGSA,A,1,99.99,99.99,99.99,2*30\r\n’

end

start

b’$GNGSA,A,1,99.99,99.99,99.99,3*31\r\n’

end

start

b’$GNGSA,A,1,99.99,99.99,99.99,4*36\r\n’

end

start

b’$GPGSV,1,1,00,0*65\r\n’

end

start

b’$GLGSV,1,1,00,0*79\r\n’

end

start

b’$GAGSV,1,1,00,0*74\r\n’

end

start

b’$GBGSV,1,1,00,0*77\r\n’

end

start

b’$GNGLL,V,N*7A\r\n’

end

start

b’$GNRMC,V,N,V*37\r\n’

end

start

b’$GNVTG,N*2E\r\n’

end

start

b’$GNGGA,0,00,99.99,*56\r\n’

end

start

b’$GNGSA,A,1,99.99,99.99,99.99,1*33\r\n’

end

You can check the attachments for reference, thanks for the help.

Success: https://carlton-public.s3.ap-southeast- … ccess.jpeg

Failure:https://carlton-public.s3.ap-southeast- … ilure.jpeg

2

Hi,

Just for information, the ZED-F9P defaults to 38400 baud, not 9600. But that only applies on true Serial (UART) connections - not USB.

Are you using the same antenna - with the same cable - in both tests? The new ZED is working correctly, but it is not getting a signal from the antenna. Please check the antenna connections and that the antenna has a clear view of the sky.

I hope this helps,

Paul

3

Hey Paul,

Yeah, I am using the same raspberry PI and antenna(ublox) which is also part of this kit https://www.sparkfun.com/products/18292.

All the other hardware(Raspberry PI, antenna, cables) and environment remain the same except I simply switch the ZED-F9P boards when doing these two tests.

Regarding the antenna connection, I am pretty sure it’s plugged in very well.

I changed the baudrate to 38400, still no GPS datahttps://carlton-public.s3.ap-southeast- … 38400.jpeg

4

Hi,

It looks like it is working - a little. You have the correct time in the GGA message. And the GSV messages contain some information about the satellites. Check the antenna has a clear view of the sky - and give it more time. It can take about a minute to get a fix - from a “cold start”.

Best wishes,

Paul

5

Hey Paul,

Thanks for the prompt reply, yeah, it’s a clear view of the sky, I also waited for around 10 minutes for it to get warm, but still no good, still shows the correct time.

I noticed that on the working board, the pps yellow light is flashing, but on the non-working board, the yellow light is off, any thoughts? much appreciated

6

Hi,

Maybe it is getting a signal - but only a very weak one? The u-blox antenna is active, it needs 3.3V to work correctly. If the 3.3V is not present, it may still work but the signal will be very, very weak. You can check with a multimeter. Take anti-static precautions, and then carefully measure the voltage between the SMA center pin and GND. You should see close to 3.3V DC. If it is close to 0V, it indicates a problem with the resistor and inductor that provide the power. Maybe one of them has a bad solder joint?

I hope this helps,

Paul

7

Hey Paul,

Thanks again for the reply, we are a mainly software company so we don’t have that multimeter or much hardware knowledge, when you mention “it indicates a problem with the resistor and inductor”, do you mean it’s the board’s problem? if so can we return it back for check and get a replacement? Thanks

8

Hi,

Please fill in the form at: https://www.sparkfun.com/returns . Thank you.

Best wishes,

Paul