sim voltage generation problem in gsm module

[gsmman]

Hi friends,

I am working with wavecom Q2686 module. My problem is that when the module is powered on , the module is not producing the voltage to drive my SIM card(sim vdd). i am using 8 pin sim card connector. I have connected with pc and checked the basic AT commands. The module is responding to the basic commands like AT , which return with OK. the sim interface in my board is same as given in the wavecom q2686 datasheet.

Please help me.

Thank you
Roy

 

[pranam77]

I am not sure about the said GSM module, but GSM module like the SIM300 powers the sim only when it is detected. In case you measure volatge at the sim socket without the sim, You'll not find the volatge...Cheers

 

[gsmman]

Exactly!
Its working !! []

 

[chethankp]

Hi,
I have designed th new board using q 2686 ,but its not working .. I have posted complete details in the following link https://www.edaboard.com/threads/189742/#post793374

pls help me.. I'm struggling too much to find out problem .

regards
raveesa

 

[Enlightenment]

Each flavor of SIM and Smart Card can work at different voltages. The manufacturer defines the voltage classes in which the device will work, which could be any 1 or 2 or all 3. Class A = 5V, Class B = 3V, Class C = 1.8V. Subscriber Identity Module - Wikipedia, the free encyclopedia

Since many SIM / Smart Cards are compatible with 2 voltages, either (5V and 3V) OR (3V and 1.8V), thus if you want to pick a single interface voltage, then 3V is probably the best choice across multiple vendors.

Most SIM and Smart Card readers will not supply power to them until after it physically detects the cards being inserted.

 

[chethankp]

Hi,

I have tested the sim with evaluation board its working there..
they drive that with 1.8v only..

But in my design its not working, even serial port is also not working(to connect to the PC to see the AT commands)..

what may be the problem..

regards
revee

 

[Enlightenment]

Please provide the following:
- Online link to the technical manual of that GSM module.
- Exact description of how you are attempting to connect computer to GSM module and other device to GSM module. Specify exactly what is connected to what and how you are connecting them. What is the wiring diagram between the devices?

Since none of us are standing right next you, then you need to provide exact descriptions, otherwise you are wasting both your time and our time.

 

[chethankp]

Hi,
Here are the full details .

Link to the development kit (which i have used as reference for my design) **broken link removed**
link to the tech specs of Q2686 module https://www.gprsmodems.co.uk/q2686/WISMO_Quik_Q2686_PTS.pdf ..

Connect with PC:
First I have bought the evaluation board for the q2686 and I connected to PC through RS232 cable .
we programmed the same SMS service program using M2M studio , it was working fine .. At commands was aorking on the com port.
Sencond: I have removed the module(which is programmed for SMS service) from the evln board and put in to my designed board,i have used the same connection cable b/w the PC and the module , here nothing was working. I was not receiving any commands at least startup mes of module. No SMS messages also.
I have followed same ckt which has given in the reference doc
Sch of my design https://www.edaboard.com/threads/189742/#post793374

 

[Enlightenment]

One of my concerns is the pins numbers on the DB9 on your schematic doesn't match the common pin2 and pin3 for transmit and receive. Maybe you numbered it differently, just a guess.

Use a scope / meter or some device to check each pin of your cable when it's plugged into your computer, but not your device. Send some chars from your computer, then determine which pin it shows up on the cable. Next plug the cable into your board. Repeat then walk the signal through your schematic. The characters from your comptuer should show up at the correct pins of U7 or you have a wiring problem.

Since I don't have a datasheet for part U7, I can't tell if it is wired correctly to the RS232 converter U8 chip. Do you have link to the datasheet for Q2686LOGIC U7 part???

Please revalidate and cross reference the pins of J18 to the RS232 cable. As I stated above, the pinout doesn't appear to match the common DB9 standard. I highly recommend that you number pins the same way on a schematic as they appear on the DB9 connector!!!! It is a BIG MISTAKE to number pins on a common connector in the wrong way, because it only causes confusion!!!

---------- Post added at 02:49 ---------- Previous post was at 02:36 ----------

The MAX3237E part has a working VCC voltage of 3.0V to 5.5V, but you are running it at 2.8V.

 

[chethankp]

Hi,
I didnt get the Exact datasheet of Q2686(I contacted vendor also), I got the reference manual to the same.
here is the link . **broken link removed**

I drove the max IC with 3.3 volt and I verified the wiring connection of DB9 and board side , all these connection are okay..
Still same problem is existing.

thanks and regards

 

[chethankp]

Hi ,
Thanks for the support.
Now I'm able to connect to PC and able to receive the respones for at commands .

Now I'm facing at the sim connection . its not detecting the SIM..

what may be the problem ..?

regards
chethan

 

[bornfree]

Exactly!
Its working !! []

Hi There,

I have the exact same problem but i have my Sim present pin connected. I still don't get any voltage on the SIM VCC. My Sim pins are connected directly to the Q2686 pins. Can some please help me fix this? Or just post the SIM interface circuit?

Thanks for you time