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[SOLVED] SIMCOM SIM548c-EVB with SIM908C gives wrong Latitude from AT-CGPSINFO=2 command

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Johanvz

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Hello everyone,

I'm new to working with SIMCOM units and I have a question to anyone that knows the SIM908 module. I'm currently working with it on the SIM548C-EVB board and I am getting the wrong GPS latitude reading.


The commands and output:

AT+CGPSSTATUS?
+CGPSSTATUS: Location 3D Fix

OK
AT+CGPSINF=2
2,065540,1564.857861,S,2450.196523,E,1,9,0.918522,1536.112427,M,22.779541,M,,000
OK

Now for the Latitude, the value 1564.857861,S is incorrect? As it is in the format ddmm.mmmmmm but the minutes part is out of range as it should not be more than 60 anyway. Ontop of that, the actual value that I am expecting is 2604.851567,S and not 1564.857861,S. The longitude value is 100% correct.

If I look at the output ont he debug port, the values are all correct, so it is just from the AT command when I query the value that it is incorrect.

Sample from debug UART:

$GPGGA,074001.000,2604.851567,S,02450.202795,E,1,8,1.00,1548.101,M,22.780,M,,*7E
$GPGLL,2604.851567,S,02450.202795,E,074001.000,A,A*45

Any suggestions would be welcome.

Oh, the version info:
AT+GSV
SIMCOM_Ltd
SIMCOM_SIM908
Revision:1137B02SIM908M64_ST

Thanks in advance for you help.
 

Johanvz said:
Hello everyone,

I'm new to working with SIMCOM units and I have a question to anyone that knows the SIM908 module. I'm currently working with it on the SIM548C-EVB board and I am getting the wrong GPS latitude reading.


The commands and output:

AT+CGPSSTATUS?
+CGPSSTATUS: Location 3D Fix

OK
AT+CGPSINF=2
2,065540,1564.857861,S,2450.196523,E,1,9,0.918522,1536.112427,M,22.779541,M,,000
OK

Now for the Latitude, the value 1564.857861,S is incorrect? As it is in the format ddmm.mmmmmm but the minutes part is out of range as it should not be more than 60 anyway. Ontop of that, the actual value that I am expecting is 2604.851567,S and not 1564.857861,S. The longitude value is 100% correct.

If I look at the output ont he debug port, the values are all correct, so it is just from the AT command when I query the value that it is incorrect.

Sample from debug UART:

$GPGGA,074001.000,2604.851567,S,02450.202795,E,1,8,1.00,1548.101,M,22.780,M,,*7E
$GPGLL,2604.851567,S,02450.202795,E,074001.000,A,A*45

Any suggestions would be welcome.

Oh, the version info:
AT+GSV
SIMCOM_Ltd
SIMCOM_SIM908
Revision:1137B02SIM908M64_ST

Thanks in advance for you help.
Click to expand...

Your module's version is B02, pls update to B03, it can solve your problem.
 
Hi, do you know where i can find the firmware and the updater tool ?. Thanks in advance.
 

I've got the b02 version of the firmware, im not who opened this thread, but i had similar problems.
I found out, the data showed by the device was indeed correct, the problem was the format. The datasheet says than the coordinates are in format ddmm.mmmm , and that's wrong. The given format by the device is mmmm.mmmmm. After a while i realized that, and coulde parse the coordinates correctly. Im working on a gps tracker, for an academic assignment. I dont think i will update the firmare due to damage something, time is running, and this devices are rare and expensive in argentina (~70 u$s). But, it would be usefull to anyone who google "how to" or "where to", to upload the tools somewhere.
There is not much usefull information out there, and it could be great, if we start sharing info and "walkthroughts" about how to use sim908.
Thanks in advance, and apologies for my english.
 

gosurata said:
I've got the b02 version of the firmware, im not who opened this thread, but i had similar problems.
I found out, the data showed by the device was indeed correct, the problem was the format. The datasheet says than the coordinates are in format ddmm.mmmm , and that's wrong. The given format by the device is mmmm.mmmmm. After a while i realized that, and coulde parse the coordinates correctly. Im working on a gps tracker, for an academic assignment. I dont think i will update the firmare due to damage something, time is running, and this devices are rare and expensive in argentina (~70 u$s). But, it would be usefull to anyone who google "how to" or "where to", to upload the tools somewhere.
There is not much usefull information out there, and it could be great, if we start sharing info and "walkthroughts" about how to use sim908.
Thanks in advance, and apologies for my english.
Click to expand...

Hi, gosurata,
I can understand you.Never mind!
If you do not want to update the firmware, pls get the GPS information from GPS/DBG-TXD、GPS/DBG-RXD, but not AT.
 

Echo wang said:
Hi, gosurata,
I can understand you.Never mind!
If you do not want to update the firmware, pls get the GPS information from GPS/DBG-TXD、GPS/DBG-RXD, but not AT.
Click to expand...

I dont understand this: i am reading the gps from the serial port, (RXD, TXD), the data im reading is correct why should i use GPS-DBG port? . I have just to adjust the parsing program i will use to adquire that data, because of the "error" in the format given by the device (but i suspect than the problem was in the translation of the documentation).
After i finish some part of the project i am working, i try to upload there, with some points. It could help future developers to get a "start point" to get a functional sim908, without the evaluation kit. (I am working without it, i just -welded- little coper wires from the chip pins, to a square test board surronded by pins). Until then thanks you very much!.
 

gosurata said:
I dont understand this: i am reading the gps from the serial port, (RXD, TXD), the data im reading is correct why should i use GPS-DBG port? . I have just to adjust the parsing program i will use to adquire that data, because of the "error" in the format given by the device (but i suspect than the problem was in the translation of the documentation).
After i finish some part of the project i am working, i try to upload there, with some points. It could help future developers to get a "start point" to get a functional sim908, without the evaluation kit. (I am working without it, i just -welded- little coper wires from the chip pins, to a square test board surronded by pins). Until then thanks you very much!.
Click to expand...

Hi, Gosurata, yes, you are correct.But there is bug in B02 version, if the data out of from TXD RXD, the fomate is wrong. if out from GPS/DBG, it's right. B03 version has corrected it.
 

Echo wang said:
Your module's version is B02, pls update to B03, it can solve your problem.
Click to expand...

I have B03 firmware, but similar problem:

AT+GSV
SIMCOM_Ltd
SIMCOM_SIM908
Revision:1137B03SIM908M64_ST

OK
AT+CGPSINF=0
0,-116.307060,5146.339662,71.616142,20120731145145.000,257,12,0.000000,88.816719
OK
AT+CGPSINF=32
32,150007.000,A,5146.339662,N,116.307060,W,0.00,88.82,310712,,E,A
OK
Click to expand...

My location should be 51.77XXXX,-1.27XXXX

I have to use AT commands to poll GPS, due to limited number of async ports in the existing hardware platform I am using.
 

Hi, Markwj, pls offer a e-mail to me, I send the file to you about your question.


markwj said:
I have B03 firmware, but similar problem:



My location should be 51.77XXXX,-1.27XXXX

I have to use AT commands to poll GPS, due to limited number of async ports in the existing hardware platform I am using.
Click to expand...
 



markwj said:
Got the document. Thanks. Very useful.

I see the problem is the SIM908 gives the coordinates in ddmm.mmmmmm format, but my other tools gives it in decimal. Converting the degrees and minutes with https://transition.fcc.gov/mb/audio/bickel/DDDMMSS-decimal.html/ shows them to match, so I'm happy and can now work out how to do that in PIC 8bit code...
Click to expand...

Hello this is very helpful!

Can you say to me something about Altitude?
Is it in meter? In which format is it?

thank you again..

Marco
 

Can u please tel me what is cost of sim548-evb board and where did u buy. I am also in need of it. And what about sim908, which one is best sim548c or sim908
 

rajath s said:
Can u please tel me what is cost of sim548-evb board and where did u buy. I am also in need of it. And what about sim908, which one is best sim548c or sim908
Click to expand...

Hi, rajath, both SIM548 and SIM548C have been phased out for 2years, there is SIM908 and SIM908C only. SIM908 is SMT module, SIM908C is DIP module. we have stock of SIM908 and SIM908C EVB KIT, for detail, pls send e-mail to me: Echo.Wang@haozetech.com
 
hi everyone, not wanting to necro a thread but im having the same problem...here what i do...

Code: 
AT+CGMR

                                                                     
                                                                                
Revision:1137B03SIM908M64_ST

                                                
                                                                                
OK
                                                                            
AT+CFUN=0

                                                                   
                                                                                
OK
                                                                            
AT+CGPSPWR=0

                                                                
                                                                                
OK
                                                                            
AT+CGPSPWR=1

                                                                
                                                                                
OK
                                                                            
AT+CGPSRST=0
                                                                  
              
                                                                
OK
                                                                            
AT+CGPSSTATUS?
                                                                
                
                                                              
+CGPSSTATUS: Location Unknown
                                                 
                               
                                               
OK
                                                                            
AT+CGPSSTATUS?
                                                                
                
                                                              
+CGPSSTATUS: Location Unknown
                                                 
                               
                                               
OK
                                                                            
AT+CGPSSTATUS?
                                                                
                
                                                              
+CGPSSTATUS: Location Unknown
                                                 
                               
                                               
OK
                                                                            
AT+CGPSSTATUS?
                                                                
                
                                                              
+CGPSSTATUS: Location 3D Fix
                                                  
                              
                                                
OK
                                                                            
AT+CGPSINF=0
                                                                  
              
                                                                
0,-923.540373,3922.181532,99.735992,20130408124722.000,32,9,0.000000,0.000000
 
OK

my current latitude is 39.369711 and long is -9.392495

is this firmware bugged? something else?...cant get it....
 

dismiss my last topic....

GPS sends coords in DDDMM.MMMMMM

No seconds....

RTFM trough the end at its best...
 
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