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Cherokeecruiser
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Joined: 25/02/2015
Location: Australia
Posts: 25

Posted: 03:14am 27 Feb 2017

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Hi Everyone

I have a question regarding the GPS function. On my MM extreme (100 pinner) The GPS function works perfectly on com1 and com2. If I open com 3 as gps, and a valid gps signal is connected, the function never returns a valid signal and If I open Com 4 as GPS the cpu crashes. If I open com3 and com4 as a normal serial port with a GPS connected i can read perfect GPS data from the buffer. Is the function limited only to com1 or com2

I am curious if I have missed something, or whether anyone else has observed this behaviour

Thanks

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 8600

Posted: 04:02am 27 Feb 2017

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Looks like a cut and paste error - I'll post a corrected version late today

UPDATE

Are you using the BACKPACK144? If so you mustn't use COM4 unless you remove the PIC16F1455 as otherwise you have two outputs driving against each otherEdited by matherp 2017-02-28

Cherokeecruiser
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Joined: 25/02/2015
Location: Australia
Posts: 25

Posted: 02:53am 28 Feb 2017

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Hi Matherp

Thanks for the reply and just confirming I'm not using a BACKPACK144 - it is aboard of my own design, with com3 dedicated to the gps , (com4 to ESP8266 , com 2 to emic speech module and com1 to SIM 5320 - com 1 and 2 yet to be populated!)

Thanks again for all your and Geoff's hard work in producing such a fantastic device.

Cherokeecruiser
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Joined: 25/02/2015
Location: Australia
Posts: 25

Posted: 04:31am 12 Mar 2017

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I think I may have found an anomaly with the GPS function. If the GPS has a valid signal I can open a com port as GPS successfully. If the GPS hasn't acquired a signal, opening any com port as GPS causes the micromite to hang.

I have a simple program running in which I sync the system time with the gps time every time it starts. If the GPS has a good view of the sky and has been powered on, the program runs successfully. If i put the gps module in a filing cabinet where it gets no signal the running program crashes after about 10 seconds with a CPU Exception #0 at address 0x9D0D68E4

It is happening on a Micromite extreme 100 Pin with the latest release 5.3.13

matherp
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Joined: 11/12/2012
Location: United Kingdom
Posts: 8600

Posted: 05:08am 12 Mar 2017

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I'd hoped I'd trapped this issue which I saw on one of my GPS but clearly not.

The problem is that different GPS units seem to send different versions of the messages if the signal is non-valid. The parser tries to interpret them but if they are syntactically incorrect it can cause this error.

To fix this I need you to read the incoming signal using a normal serial port and post the full text of the messages RMC and GGA when the signal is NOT valid. Then I can try and find the bit of the parser that is failing

Cherokeecruiser
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Joined: 25/02/2015
Location: Australia
Posts: 25

Posted: 02:49pm 12 Mar 2017

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GPS Module - SKM53

Full text of RMC and GGA text working and not working follows:

WORKING - VALID FIX
$GPRMC,002638.000,A,2723.9971,S,15302.8100,E,0.00,244.15,130317,,,A*73
$GPGGA,002639.000,2723.9971,S,15302.8100,E,1,7,1.35,-1.3,M,37.3,M,,*69
$GPGSA,A,3,25,02,05,12,20,29,24,,,,,,2.58,1.35,2.20*06
$GPGSV,3,1,11,12,81,020,24,05,57,067,31,50,56,342,,25,52,224,27*73
$GPGSV,3,2,11,02,43,146,40,20,34,354,16,29,28,232,37,24,15,336,24*7E
$GPGSV,3,3,11,06,07,132,,19,04,090,,31,02,223,*4E

NOT WORKING - NO VALID FIX
$GPRMC,003324.000,V,2723.9908,S,15302.8300,E,0.00,0.00,130317,,,N*68
$GPGGA,003325.000,2723.9908,S,15302.8300,E,0,0,,-6.0,M,37.3,M,,*77
$GPGSA,A,1,,,,,,,,,,,,,,,*1E
$GPGSV,3,1,11,12,78,017,,05,58,073,,25,55,227,,02,41,145,*7A
$GPGSV,3,2,11,20,38,354,,29,29,229,,24,13,338,,06,04,131,*77
$GPGSV,3,3,11,19,03,087,,31,03,225,,21,02,298,*4B

matherp
Guru

Joined: 11/12/2012
Location: United Kingdom
Posts: 8600

Posted: 01:59am 13 Mar 2017

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I've replaced the GPS parser with a different, simpler, version.

Please download the new firmware and let me know if this helps - no change in version number

I've also added some new functionality when the GPS is "open"

PRINT #GPS,"$GPScommand*"

This sends the quoted string to the GPS. Note that the string must start with "$" and end with "*" characters. The checksum is calculated automatically.

This should make it easy to send configuration commands to the GPS

Of course if you change baudrate you will need to CLOSE GPS and re-open it.

Edited by matherp 2017-03-14

Cherokeecruiser
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Joined: 25/02/2015
Location: Australia
Posts: 25

Posted: 04:56am 13 Mar 2017

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Quick testing only (due to the late hour here) - seems to have fixed the problem completely

Thanks again

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