GPS component mistake?

For Flowcode users to discuss projects, flowcharts, and any other issues related to Flowcode 7.

Moderator: Benj

radist73
Posts: 36
Joined: Mon Dec 22, 2014 10:04 pm
Location: TALLINN
Has thanked: 5 times
Been thanked: 2 times
Contact:

GPS component mistake?

Postby radist73 » Tue Aug 07, 2018 12:32 pm

Hi,
Just tryed GPS component to read Latitude and Longtitude, but seems as Latitude read fail and really it have read Altitude.
Longtitude read show 24, 774 (Tallinn, Estonia) it is OK result, But Latitude read is between 5,xxx and 6,xxx, but need to be a 59,430. Before any steps of update it works fine (~1 year ago).
ReadLatitude and ReadAltitude give the same result. Data in GPS receiver output is ok.
Could you check it?
My flowchart attached.
Master side every 15sec ask for GPS cootdinates of slave side by RF LoRa transceiver connected to UART1

Thanks!
Attachments
RX3_26k22.fcfx
(24.92 KiB) Downloaded 38 times

User avatar
Benj
Matrix Staff
Posts: 14371
Joined: Mon Oct 16, 2006 10:48 am
Location: Matrix TS Ltd
Has thanked: 4447 times
Been thanked: 4145 times
Contact:

Re: GPS component mistake?

Postby Benj » Wed Aug 08, 2018 11:46 am

Hello,

I can't see any problems in the component source. Are you using the latest (v7.3) and have you applied the fixes listed here.

viewtopic.php?f=63&t=19743

radist73
Posts: 36
Joined: Mon Dec 22, 2014 10:04 pm
Location: TALLINN
Has thanked: 5 times
Been thanked: 2 times
Contact:

Re: GPS component mistake?

Postby radist73 » Fri Aug 10, 2018 3:12 pm

Hi,
Now I have made a simple program with PIC18F26K40, I2C LCD and GPS module for testing. It start working with Software i2c.
But position read is strange. Longtitude is stable 24,774xxx but Latitude hops between 59,096 and 60,430 (it is approx. 200km distance) Right value must be 59,429

User avatar
petesmart
Valued Contributor
Valued Contributor
Posts: 395
Joined: Thu May 06, 2010 11:42 am
Location: Sydney, Australia
Has thanked: 190 times
Been thanked: 140 times
Contact:

Re: GPS component mistake?

Postby petesmart » Fri Aug 10, 2018 10:17 pm

Hi,

Sounds like a GPS problem rather than a coding/component problem.

As a suggestion, check the number of satellites that your GPS device can see...I think you need at least 8 to get a solid reference for longitude. Sometimes the GPS device can not see a wide enough arc of the sky, I often use an external antenna when I’m developing in the lab...

From memory I think the component allows you to check no of satellites visible..

Edit...I also note in your post that you have a LORA transceiver operating simultaneously....I would turn off the LORA device and re test GPS stability to check your not getting any RF interference or GPS rx front end overload....even though both device might not be on the same frequencies, harmonics often fall within rx passband of the GPS rx..if this is the case then the GPS will definitely be unstable...

Once we prove this is the case or not, then we can look at RF design


See how you go..

Best

Pete
sorry about that Chief!

radist73
Posts: 36
Joined: Mon Dec 22, 2014 10:04 pm
Location: TALLINN
Has thanked: 5 times
Been thanked: 2 times
Contact:

Re: GPS component mistake?

Postby radist73 » Sun Aug 12, 2018 11:54 am

Hi,
Thanks for answer.
My last test program have only GPS and LCD, file attached, and have same problem.
I have tested GPS with LCD about year ago, when just purchased FC7, it works fine. GPS receiver send out position data only if it receive signals from needed number of satellites, I have tested it in different places and outside.

Edit: will test other type of GPS receiver, may be problem in chineese GPS device (2pcs tested, result is same)
I have this model https://m.banggood.com/GPS-Module-with- ... 00984.html
Attachments
TX3_25K42_LCD_GPS.fcfx
(25.58 KiB) Downloaded 41 times

radist73
Posts: 36
Joined: Mon Dec 22, 2014 10:04 pm
Location: TALLINN
Has thanked: 5 times
Been thanked: 2 times
Contact:

Re: GPS component mistake?

Postby radist73 » Mon Aug 13, 2018 1:28 pm

Just checked it again, GPS receiver connected to PIC and receiver output connected to Terminal. In terminal window GPS signal have stable fixed values, but LCD show fixed Longtitude value and unstable 59,xxx-60,xxx latitude value... :(

kersing
Valued Contributor
Valued Contributor
Posts: 1873
Joined: Wed Aug 27, 2008 10:31 pm
Location: Netherlands
Has thanked: 530 times
Been thanked: 1040 times
Contact:

Re: GPS component mistake?

Postby kersing » Mon Aug 13, 2018 2:20 pm

It might help for debugging if you provide output from the GPS as seen in the terminal.
“Integrity is doing the right thing, even when no one is watching.”

― C.S. Lewis

User avatar
Benj
Matrix Staff
Posts: 14371
Joined: Mon Oct 16, 2006 10:48 am
Location: Matrix TS Ltd
Has thanked: 4447 times
Been thanked: 4145 times
Contact:

Re: GPS component mistake?

Postby Benj » Mon Aug 13, 2018 4:38 pm

Hello,

Can you output the number of satellites.

Could it be that when connected to the PC you are getting many more satellites then you are when connected to PIC?

Are you running the GPS module inside or outside?