Telit SIM Card problem - Random shutdown

[Madnac]

Telit SIM Card problem

Hi,


I'm confronting to a problem with my Telit GM862 where i can't find any answer in manual and on Internet (after three months of search) :


The problem : sometimes, after four or five days, the modem shuts down and doesn't want to restart because he says there is no SIM Card present.


So, for launch again the modem, the only solution that i found is to eject/insert the SIM card to the modem (disconnected the batterie does not do nothing). Not very pratical...! So i tried many kind of test to see where this comes from (antenna, power, µC...), but nothing changed.

But a few days ago, i found something interesting where, i suppose, somebody could help me : when the modem shuts down (due to this bug) and when i try to restart, i notice that the voltage of SIMVCC has irregular value like 1V to 3V at 1Hz... If i eject/insert SIM card, everything goes right and SIMVCC indicates 3V directly.

So i suppose that SIM Card is temporarily damaged by interference or something (i tried to interchange the 10 SIM cards but always the same PCB have the problem). I hope someone knows it, or had the same problem with an other modem (Telit or not) because Telit support don't want to help me because i'm not a big customer (just 10 GM 862...)


Thanks you for your help.

Pierre



Details :
- This is my own PCB (kind of weather station)
- I produced 10 PCB like this. 4 working well and 6 have this problem (it's also the more disturbing, not the 10 cards but only 6 don't work)
- The power line has been already verified : batterie Li-ion 3.7V 2200mAh, capacitor low ESR Tantal 220uF. No problem to start (and to call).
- The communication through UART (with PIC18LF4620) is ok.

 

[msvalkon]

Re: Telit SIM Card problem

I know this is an age old thread but we're facing a similar issue, although cannot confirm the voltage values.

Did you eventually find the root cause for this issue?

Hi,


I'm confronting to a problem with my Telit GM862 where i can't find any answer in manual and on Internet (after three months of search) :


The problem : sometimes, after four or five days, the modem shuts down and doesn't want to restart because he says there is no SIM Card present.


So, for launch again the modem, the only solution that i found is to eject/insert the SIM card to the modem (disconnected the batterie does not do nothing). Not very pratical...! So i tried many kind of test to see where this comes from (antenna, power, µC...), but nothing changed.

But a few days ago, i found something interesting where, i suppose, somebody could help me : when the modem shuts down (due to this bug) and when i try to restart, i notice that the voltage of SIMVCC has irregular value like 1V to 3V at 1Hz... If i eject/insert SIM card, everything goes right and SIMVCC indicates 3V directly.

So i suppose that SIM Card is temporarily damaged by interference or something (i tried to interchange the 10 SIM cards but always the same PCB have the problem). I hope someone knows it, or had the same problem with an other modem (Telit or not) because Telit support don't want to help me because i'm not a big customer (just 10 GM 862...)


Thanks you for your help.

Pierre



Details :
- This is my own PCB (kind of weather station)
- I produced 10 PCB like this. 4 working well and 6 have this problem (it's also the more disturbing, not the 10 cards but only 6 don't work)
- The power line has been already verified : batterie Li-ion 3.7V 2200mAh, capacitor low ESR Tantal 220uF. No problem to start (and to call).
- The communication through UART (with PIC18LF4620) is ok.

 

[electronicsbasecom]

Hello,

We never have problems with the SIM cards, but generaly all problems with these modems are related with power supply. As you know peak current in some states (gprs comm.) can be up to 2A. So our sugestion is to add more capacitance, at least 1000uF.