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SIM908 problem SIMCARD

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diepvu1805

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Hi all,
I am using SIM908 modem. I have some issue with SIMCARD. I connect LED to pin NETLIGHT (SIM908)
After power on SIM908 modem, I saw this LED blink. SIM908 seem ran. But Voltage on SIM_VDD pin: 0V. BUt as follow SIM908's datasheet, voltage on this pin:1.8V or 3.3V.
I can explain that.
Pls, help me.
Thank you very much,
 

diepvu1805 said:
Hi all,
I am using SIM908 modem. I have some issue with SIMCARD. I connect LED to pin NETLIGHT (SIM908)
After power on SIM908 modem, I saw this LED blink. SIM908 seem ran. But Voltage on SIM_VDD pin: 0V. BUt as follow SIM908's datasheet, voltage on this pin:1.8V or 3.3V.
I can explain that.
Pls, help me.
Thank you very much,
Click to expand...

Pls check whether the pin can meet the diagram? It seems the module can work now.
 

Hi diepvu,
Could you tell me how did you solve this problem, i had the same problem with SIM900 some time ago and couldnt solve it (went back to sim548)
Thanks
Rod
 

Rod_O said:
Hi diepvu,
Could you tell me how did you solve this problem, i had the same problem with SIM900 some time ago and couldnt solve it (went back to sim548)
Thanks
Rod
Click to expand...

Hi, Rod, have you got the same question with diepvu1805?

- - - Updated - - -

Rod_O said:
Hi diepvu,
Could you tell me how did you solve this problem, i had the same problem with SIM900 some time ago and couldnt solve it (went back to sim548)
Thanks
Rod
Click to expand...

Hi, Rod, have you got the same question with diepvu1805?
 

Hi....

When I turn on de module without SIM card I can work in it without problems, send AT commands, get GPS data.

But when I put the SIMcard and turn on the module it giveme this:

RDY
+CSMINS: 1,1
+CFUN: 1
+CPIN: READY
+CREG: 0
+CREG: 2
GPS Ready
Call Ready
+CREG: 1

And then shuts down! And i can't do anything else.
My firmware: Revision:1137B02SIM908M64_ST

So, anybody can help me with this....

Thanks a Lot!
 

Hi Andres,
I can assure you that's a power supply problem.
I use to have the same problem with the old sim300.
Use a cellphone batterie to test this, and get back to us with the result.
Good luck
rODRIGO
 

Hi Rodrigo.

I'm using a Cell Battery from Nokia, 3.7V at VBAT pin, when the SIM Card is on VBAT pin at 3.6V...

Do you think that i have to change this battery??

If you can please contact me by private msg to talk in our native language ;)
 

andresnavas said:
Hi Rodrigo.

I'm using a Cell Battery from Nokia, 3.7V at VBAT pin, when the SIM Card is on VBAT pin at 3.6V...

Do you think that i have to change this battery??

If you can please contact me by private msg to talk in our native language ;)
Click to expand...


pls add the battery to 4.2V ,then try again.
 

I prefer talking through here so if anyone have the same problem, they can find the solution.
Pero podemos hablar en español igual ;D
Prueba cambiar la bateria como sugiere Echo Wang, y nos avisas.
Suerte
 
HI. Trying using a External Power Supply 4.2V and 4.38V both at @ 3A

Same problem!!.... :(
 

mmMMm.. Bad thing.
Maybe the programm you are running ? Can you post both tthings to see if i can find the problem??
Suerte
Rod
 

I'm not running any program, for now i'm opertating the module by an RS232 to USB converter to my PC using a terminal (TeraTerm).

I just start the module with the SIM card in position and have this from the module:
RDY
+CSMINS: 1,1
+CFUN: 1
+CPIN: READY
+CREG: 0
+CREG: 2
GPS Ready
Call Ready
+CREG: 1
Then the module shut down...

If I don't put the SIM card the module starts normaly:
RDY
+CSMINS: 1,1
+CFUN: 1
+CREG: 0
+CREG: 3
GPS Ready
And then it stills on and i can work with it and check GPS por example...

:-?
:sad:
 

Hi Andres,
Defenietly is your power source, because when the the moduñe tries to connect with the nearest cellphone antenna, it drains a lot of current (max 2A) during burst.
And that problem is very common. The power source can not change it's voltage output during burst and that's very tricky, so focus on that.
Im sure that's your problem, beacuse when you don't put the sim card, the module doesn't try to lock with the cellphone antenna, and that's why it doesnt shut off in those cases.
Good Luck
Rod
 
HI.

Problem solved! No need extra power... Only have to add a 4700uF capacitor near to VBAT pin. SIM908 working good...

For now, anyone has an example of use to send commands to a HTTP server?

Thanks a Lot!
 

Great Andres,
Happy to hear that.
I have not use HTTP server com with sim module sorry... Good luck and please keep sharing your goals (and problems)
Rod

andresnavas said:
HI.

Problem solved! No need extra power... Only have to add a 4700uF capacitor near to VBAT pin. SIM908 working good...

For now, anyone has an example of use to send commands to a HTTP server?

Thanks a Lot!
Click to expand...
 

andresnavas said:
HI.

Problem solved! No need extra power... Only have to add a 4700uF capacitor near to VBAT pin. SIM908 working good...

For now, anyone has an example of use to send commands to a HTTP server?

Thanks a Lot!
Click to expand...


Hi, andresnavas, I have it, how could I send to you?
 

andresnavas said:
HI.

Problem solved! No need extra power... Only have to add a 4700uF capacitor near to VBAT pin. SIM908 working good...

For now, anyone has an example of use to send commands to a HTTP server?

Thanks a Lot!
Click to expand...

Hello Andres,
Where did you add this capacitor..? is there a short rough sketch of the schematic that you can share perhaps ?
thanks
Stap

- - - Updated - - -

andresnavas said:
HI.

Problem solved! No need extra power... Only have to add a 4700uF capacitor near to VBAT pin. SIM908 working good...

For now, anyone has an example of use to send commands to a HTTP server?

Thanks a Lot!
Click to expand...

Hello Andres,
Where did you add this capacitor..? is there a short rough sketch of the schematic that you can share perhaps ?
thanks
Stap
 

I have similiar problem ( but not exactly ),

I use Sim548c and i suppose it is the same characteristic with sim900.
I posted new thread a while ago, https://www.edaboard.com/threads/270206/
Schema is shown in image
HTML: 
https://www.edaboard.com/attachments/82161d1351656747-sim548c-gsm.jpg
the device seems to work, i can see from the led attached to the status pin.
but the arduino seems hard to detect that the device is available so I can not use AT command and doesnt show RDY retun value from the terminal.
Please help to fix this.
 

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