SparkFun Forums

[DannyDJ]

Hello! Today I've tested my new board and now works great. So before i had bad connections and that was the reason that my old board didn't work.

My TELIT is now configured like this:

RXD(which is output) pin connected -> RX RS232
TXD(which is input) pin connected -> TX RS232
GND is connected to pins 2,4,6 looking from TELIT MOLEX connector
VBATT is connected to pins 1,3,5,7 looking from TELIT MOLEX connector
I didn't grounded RTS pin(in Hardware user guide says it must be grounded if using only 3 lines for communicating).

STATUS pin to -> green LED diode
PWRCTL pin to -> red LED diode

ON/OFF to button
RESET to button

But now i have another problem.

I want to send an SMS but it's giving me an error +CREG:0,2 (Mobile is currently not registered on any network but is looking for a suitable one to
register.) and than after few seconds TELIT shuts down.

Tnx for all replays!

[Alaris]

Problem solved!

The clock speed had a multiplier I was unaware of so I calculated my baud rate incorrectly. After correcting this we sent AT<cr> and recieved the OK response with no problems.

Thanks everyone!

[enzymaticthc]

Hi - am interested in code to call SMS from arduino chip - is this very different from the chip set you used / could you share your code to do this?

Thank you

[maokh]

AT\Q[<n>] Set command controls the RS232 flow control behaviour.

Telit also has the AT+FLO. Just set it to 0.

If you dont use flow control make sure you impliment a check some for data transfer AND NEVER TRY A FIRMWARE UPGRADE WITHOUT FLOW CONTROL

The telit is a pretty robust module. Firmware upgrades can fail without any real damage. In nearly all cases, the worst you can do, is blow off any trace of software. But no worries, the bootloader will immediately come up on module start (making STAT_LED solid) waiting for some good code.

Maybe I just live dangerously, but i do firmware upgrades without flow control lines hooked up on all my telit's.

I want to send an SMS but it's giving me an error +CREG:0,2 (Mobile is currently not registered on any network but is looking for a suitable one to
register.) and than after few seconds TELIT shuts down.

If a telit module shuts down during registration, it is almost always power related. You are not able to source enough current for some power thirsty transmit operation (registering with the network at 2 watts), the voltage sags too low, and the unit shuts down.

If you are using AC power, make sure it can give you 2A @ 3.7VDC (or whatever you are giving it). If you are using the recommended Li+ battery size, you will probably be able to source plenty of current.

You also want to make sure you have a nice tantalum cap of 100uF to give you power when you need it fast. In my experience, omitting the capacitor or using the wrong type has been pretty disastrous to operation.

[DannyDJ]

Hi! Tnx for replaying. You were right. It was power problem.I've been using standard CAPS 100uF and this is the reason that GM862-GPS was shutting down. But i did a little test. How big must be the standard CAPACITITOR that module doesn't shut down during registration on network.In my case I had to use like 7000uF or above . But using tantal CAPS or low ESR capacititors of 100uF is important if you want to avoid this problem.

BYe bye

[maokh]

low ESR 100uF tantalums can be pretty expensive, and when i saw that in the hardware guide, i blew it off and just used some 100uF lead electrolytic. I couldn't find the tantalums over a few uF locally anyway. I even got a 2200uF lead electrolytic monster just to be sure.

The telit had problems during start up with both types. Didn't work with that type of cap. period. Looks like you threw 7000uF at it. I dont really have room for that.

I broke down, ordered some 100uF low ESR tantalums online, put it in the circuit -- unit works perfectly and has never had any power problems.

I put 100uF low ESR tantalums in all my designs.