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GPS Tracker using SIM908

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Hi Echo Wang,

Nice to get in touch with Simcom expert, I just sent you a private message for further discussion.

Thx, Ichan.
 

Hello,
I have a problem with my sim908.
The AT+CGMR command give me Revision:1137B02SIM908M64_ST
Where can I download a newer firmware for sim908 ?
Thank You
 

unix19x86 said:
Hello,
I have a problem with my sim908.
The AT+CGMR command give me Revision:1137B02SIM908M64_ST
Where can I download a newer firmware for sim908 ?
Thank You
Click to expand...

Yes, B02 is old version, there are some bug in it.
You can ask the newer version from the company you buying from.
Also we have it. I can send to you
 

Hi Echo wang,
i also buying the 1137B02SIM908M64_ST version and i want to update it.
can you send it?
 

I had an the same problem: module SIM908 return "Location Unknown" when i typed "AT+CGPSSTATUS?". Just conect pin 75 and 76 (V_ANT_IN and OUT) you will have the good result.
I hope it would helpful!
 

Hello Echo wang!

I am also working at a project at the moment and I am using the SIM908. I got the same problem with the GPS -> "Location Unknown".
I already connected the GPS-VANT-IN with VBAT. In this case the problem is the same "Location Unknown".

My firmware version is 1137B04SIM908M64_ST

I really need help please.

Greets from Austria
 

Serpent said:
Hello Echo wang!

I am also working at a project at the moment and I am using the SIM908. I got the same problem with the GPS -> "Location Unknown".
I already connected the GPS-VANT-IN with VBAT. In this case the problem is the same "Location Unknown".

My firmware version is 1137B04SIM908M64_ST

I really need help please.

Greets from Austria
Click to expand...
I have just finished my project, that use SIM908 to get coordinates. I have the same problem : "Location Unknow" although every thing is OK in my design.
I killed 2 SIM908 modules, after that i found the fault is :
The Battery Charging Design in the SIM908 module is so bad, when i supply 5VDC to the VCHG pin, it will kill the GPS part of the module, another part is still OK.
I send an email to SIMCOM, but the request just is the Hardware design Document, the Document i read very carefully before design.
VERRY DISSAPONTED ABOUT THIS COMPANY!
Temporary Solution: don't use Charger Part of the Module, use LM3568 to charge for the Battery.
Best Solution : Never use SIM908 in your product, find another things like: Holux....

Sorry because my bad English.
 

Ou that's bad!
I am not charging the battery while it is in use.
Yesterday I tried to charge the battery! Everything worked very well.

I guess in my case that the "Location Unknown" error is not caused by the charging design, becuse the error already occured before
I tried to charge the battery.

After you damaged 2 SIM908, worked the third one with GPS?

No problem because of your english skills, my skills aren't perfect too ;)
 

Serpent said:
Ou that's bad!
I am not charging the battery while it is in use.
Yesterday I tried to charge the battery! Everything worked very well.

I guess in my case that the "Location Unknown" error is not caused by the charging design, becuse the error already occured before
I tried to charge the battery.

After you damaged 2 SIM908, worked the third one with GPS?

No problem because of your english skills, my skills aren't perfect too ;)
Click to expand...


Hi, pls check whether it match about voltage of GPS-ANT and GPS.
Have you put the antenna outside of the room?
 

Echo wang said:
Hi, pls check whether it match about voltage of GPS-ANT and GPS.
Have you put the antenna outside of the room?
Click to expand...

The GPS VANT IN pin is connected with vbat (3.7 volts). this voltage can also be measured at the rf-con on the sim908 . so the battery supplies the gps antenna. it is an active antenna. voltage range 3-5V
do you have another suggestion what I could test ?

And yes, i also tested it outside for 10 minutes :)
 

Serpent said:
Ou that's bad!
I am not charging the battery while it is in use.
Yesterday I tried to charge the battery! Everything worked very well.

I guess in my case that the "Location Unknown" error is not caused by the charging design, becuse the error already occured before
I tried to charge the battery.

After you damaged 2 SIM908, worked the third one with GPS?

No problem because of your english skills, my skills aren't perfect too ;)
Click to expand...

Hi Serpent!
I'm not sure your problem is the same with mine,
but after i damaged 2 SIM908 modules, the third still work until now,
i don't use the charging fucntion of SIM908,
i use external charging module which has been designed by myself , use LM3568 , it's output is connected paralel with Li-ion Battery.
 

BuiPhamDuc said:
Hi Serpent!
I'm not sure your problem is the same with mine,
but after i damaged 2 SIM908 modules, the third still work until now,
i don't use the charging fucntion of SIM908,
i use external charging module which has been designed by myself , use LM3568 , it's output is connected paralel with Li-ion Battery.
Click to expand...

Hi BuiPhamDuc,

ok thanks for your respond. But the GPS also didn't work before I charged the battery the first time with SIM908.
I used to charge the battery external with a battery manager (Intelli BiPower).

Does anybody else have any ideas?
 

Ichan said:
Hi Echo Wang,

Nice to get in touch with Simcom expert, I just sent you a private message for further discussion.

Thx, Ichan.
Click to expand...

I am to this forum. Can somebody suggest a SIM 908 evaluation board? I am looking for something that is low cost and easy to work with.

thanks
 

chibane said:
I am to this forum. Can somebody suggest a SIM 908 evaluation board? I am looking for something that is low cost and easy to work with.

thanks
Click to expand...

Hi chibane!

I am sorry but I can't suggest you a evaluation board :( . I built my board myself.


@BuiPhamDuc:

I replaced my old SIM908 with a new one, because the old one broke down.
The cause was, as you already said, the charging circuit.

It worked fine and I charged the battery. Two days later I wanted to
continue programming but the SIM908 didn't start anymore.

So I replaced it.
Everything works again and I want to say to everybody: "Don't use the charging circuit! It will damage your SIM908!"

So back to my problem. It's a new SIM908 and the GPS responds again: "Location Unknown".

What I am doing wrong? Can somebody help me please? Or BuiPhamDuc, can you post your steps (at-commands) to turn on the gps and get the coordinates? It would be very nice :)
 
Last edited:

Serpent said:
Hi chibane!

I am sorry but I can't suggest you a evaluation board :( . I built my board myself.


@BuiPhamDuc:

I replaced my old SIM908 with a new one, because the old one broke down.
The cause was, as you already said, the charging circuit.

It worked fine and I charged the battery. Two days later I wanted to
continue programming but the SIM908 didn't start anymore.

So I replaced it.
Everything works again and I want to say to everybody: "Don't use the charging circuit! It will damage your SIM908!"

So back to my problem. It's a new SIM908 and the GPS responds again: "Location Unknown".

What I am doing wrong? Can somebody help me please? Or BuiPhamDuc, can you post your steps (at-commands) to turn on the gps and get the coordinates? It would be very nice :)
Click to expand...

Hi, @serpent, how long did it take to get ""Location Unknown"?

- - - Updated - - -

chibane said:
I am to this forum. Can somebody suggest a SIM 908 evaluation board? I am looking for something that is low cost and easy to work with.

thanks
Click to expand...

Hi,@Chibane, we have SIM908 evaluation board from SIMCOM, but I am not sure it meet your estimate price.
 

Serpent said:
Hi chibane!

I am sorry but I can't suggest you a evaluation board :( . I built my board myself.


@BuiPhamDuc:

I replaced my old SIM908 with a new one, because the old one broke down.
The cause was, as you already said, the charging circuit.

It worked fine and I charged the battery. Two days later I wanted to
continue programming but the SIM908 didn't start anymore.

So I replaced it.
Everything works again and I want to say to everybody: "Don't use the charging circuit! It will damage your SIM908!"

So back to my problem. It's a new SIM908 and the GPS responds again: "Location Unknown".

What I am doing wrong? Can somebody help me please? Or BuiPhamDuc, can you post your steps (at-commands) to turn on the gps and get the coordinates? It would be very nice :)
Click to expand...

Hi, Serpent, there is a GPS testing tool, for checking SIM908, are you interested in it?
Normally the first time using, it will take 2min to fix the locate.
 

is sim908 module is capable to give location during transportation. actually i wanted to install it on my car to detect location of my car while it is moving
 

Echo wang said:
Yes, B02 is old version, there are some bug in it.
You can ask the newer version from the company you buying from.
Also we have it. I can send to you
Click to expand...

I have another kind of problem: I am trying to help in a GPS tracking poject, and we need the older firmware for testing and comparing purposes. Could we get the 1137B02SIM908M64_ST firmware from somebody? At the moment we have 1137B03SIM908M64_ST. The guys asked me to search for the firmware and we would really appreciate if someone could help us out.

Thanks in advance!
 

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