myGPS.hnrPVT.nano outputting -1 all the time?

[bvernham]

Subject of the issue

Describe your issue here. If you reference a datasheet please specify which one and in which section (ie, the protocol manual, section 5.1.2). Additionally, screenshots are easy to paste into github.

Your workbench

• What development board or microcontroller are you using?
• due
• What version of hardware or breakout board are you using?
• sparkfun m8u
• How is the breakout board wired to your microcontroller?
• Serial3
• How is everything being powered?
• Due on board 5v ps
• Are there any additional details that may help us help you?

Steps to reproduce

Tell us how to reproduce this issue. Please post stripped down example code demonstrating your issue.
Serial<<myGPS.hnrPVT.nano<<"\n";
hnrPVT always returns -1 for nano

Expected behavior

Tell us what should happen
nano should have a real varying value

Actual behavior

Tell us what happens instead
hnrPVT always returns -1 for nano

[PaulZC]

Hi Bruce (@bvernham),

Looking at the code, nano is being extracted correctly. So I don't see a problem there.

Also, -1 is a valid value for nano. nano is actually an offset in the range -1e9 .. 1e9 nanoseconds (ie. +/- 1 second). It is a signed long (int32_t). You need to add it to iTOW to get the time now with nanosecond resolution - and you'll need 64-bit math to do that. (I'm not sure if the DUE implements 64-bit signed integers?)

All the best,
Paul

[bvernham]

Ok that makes some sense.  So with the hnr messages there is no easy way to get millisecond like the nav-pvt?On Jan 7, 2021 1:44 AM, Paul <notifications@github.com> wrote: Hi Bruce (@bvernham), Looking at the code, nano is being extracted correctly. So I don't see a problem there. Also, -1 is a valid value for nano. nano is actually an offset in the range -1e9 .. 1e9 nanoseconds (ie. +/- 1 second). It is a signed long (int32_t). You need to add it to iTOW to get the time now with nanosecond resolution - and you'll need 64-bit math to do that. (I'm not sure if the DUE implements 64-bit signed integers?) All the best, Paul —You are receiving this because you were mentioned.Reply to this email directly, view it on GitHub, or unsubscribe.

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[PaulZC]

iTOW is in ms. Try uint16_t millisecs = hnrPVT.iTOW % 1000;

[bvernham]

Thanks,,,On another subject I seems to be struggling with the serial communication now. I am running the the auto HNR message @ 10 hz on serial3 and sometimes hnrATT will pop up and true multiple times for each time PVR and DYN become true? Buffer overrun? Communication issue? How would I know if there is a checksum error? I know it is off subject but I have been thinking of opening another issue but if there is a simple resolution I would like to avoid another "issue". Thanks

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---------- Original Message ---------- From: Paul <notifications@github.com> To: sparkfun/SparkFun_Ublox_Arduino_Library <SparkFun_Ublox_Arduino_Library@noreply.github.com> Cc: bvernham <bvernham@juno.com>, Mention <mention@noreply.github.com> Subject: Re: [sparkfun/SparkFun_Ublox_Arduino_Library] myGPS.hnrPVT.nano outputting -1 all the time? (#174) Date: Thu, 07 Jan 2021 05:08:58 -0800 iTOW is in ms. Try uint16_t millisecs = hnrPVT.iTOW % 1000; &mdash; You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

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[PaulZC]

Hey Bruce,
Buffer overrun. You need to make sure you are calling checkUblox fast enough to prevent the data overrunning the serial receive buffer. v2.0 will make this easier for you - and I'm almost done there... Almost...
Paul

[bvernham]

I used Serial3.availible()>3 every loop but it seems make things worse?I am using millis timer which is 1/16th of the update rate which seems excessive (100 ms/16) which I woud think it would be enough. Due buffer size is 64 bytes but can be increase by tweaking the core files. The HNR messages are 72 + 36 + 32 is 140 bytes so go with 256 bytes? Any thoughts would be helpful. Thanks Bruce

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---------- Original Message ---------- From: Paul <notifications@github.com> To: sparkfun/SparkFun_Ublox_Arduino_Library <SparkFun_Ublox_Arduino_Library@noreply.github.com> Cc: bvernham <bvernham@juno.com>, Mention <mention@noreply.github.com> Subject: Re: [sparkfun/SparkFun_Ublox_Arduino_Library] myGPS.hnrPVT.nano outputting -1 all the time? (#174) Date: Thu, 07 Jan 2021 06:28:21 -0800 Hey Bruce, Buffer overrun. You need to make sure you are calling checkUblox fast enough to prevent the data overrunning the serial receive buffer. v2.0 will make this easier for you - and I'm almost done there... Almost... Paul &mdash; You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

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[PaulZC]

Time to reach for the calculator... 140 bytes is 1400 bits (at 8+1+1 bits/char). Divide by your Baud rate to find out how long the data takes to arrive. Your buffer needs to be large enough and you need to call checkUblox often enough to stop the buffer overflowing.

[bvernham]

1400/115200 = 0.01215277777777777777777777777778 I am checking every 6 ms. Why wouldn't Serial3.availible()>0 do the trick? Only call get when there is data in the buffer and do that every loop. I looked in checkublox and that is all it does is check the same thing, right? Thanks Bruce ---------- Original Message ---------- From: Paul <notifications@github.com> To: sparkfun/SparkFun_Ublox_Arduino_Library <SparkFun_Ublox_Arduino_Library@noreply.github.com> Cc: bvernham <bvernham@juno.com>, Mention <mention@noreply.github.com> Subject: Re: [sparkfun/SparkFun_Ublox_Arduino_Library] myGPS.hnrPVT.nano outputting -1 all the time? (#174) Date: Thu, 07 Jan 2021 07:06:26 -0800 Time to reach for the calculator... 140 bytes is 1400 bits (at 8+1+1 bits/char). Divide by your Baud rate to find out how long the data takes to arrive. Your buffer needs to be large enough and you need to call checkUblox often enough to stop the buffer overflowing. &mdash; You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

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[PaulZC]

If your serial buffer is 64 bytes, at 115200 Baud it will fill up in 5.6ms. Try 3ms to provide some margin?

[bvernham]

Serial buffer was originally 128 I increased to 512 and move the get statements into serialeventrun() which seems to help. I can get up to about 25 hz before I start seeing the repeats. Maybe now I need to increase the UART baud rate again. iTOW was exactly what I was looking for and work as exacted. I just wish I could find a good way to confirm the due memory usage after the compile is complete. Thanks for all help. ---------- Original Message ---------- From: Paul <notifications@github.com> To: sparkfun/SparkFun_Ublox_Arduino_Library <SparkFun_Ublox_Arduino_Library@noreply.github.com> Cc: bvernham <bvernham@juno.com>, Mention <mention@noreply.github.com> Subject: Re: [sparkfun/SparkFun_Ublox_Arduino_Library] myGPS.hnrPVT.nano outputting -1 all the time? (#174) Date: Thu, 07 Jan 2021 07:36:20 -0800 If your serial buffer is 64 bytes, at 115200 Baud it will fill up in 5.6ms. Try 3ms to provide some margin? &mdash; You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe.

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