sim300cz and atmega16L

I could solve the problem, I had to disconnect all the pins from the SP3238

Hello friend,
I have just bougth the SIM 300cz module and could you please provide me the schamtic and the pin outs how to connect the supply to the modem. I am just new and trying to make it functional.

Regards
Shan

did you see the hardware specification of SIM300cz? if not then you must check it.
if you dont have it then download it from www.sim.com

Hello there!!!
I'm developing an application using Atmel and the sim340 module.
The GSM chip that I use is a 850MHz, so I have to change the module´s band using the command AT+CBAND="850....etc"
It works fine, until I get a random error: error 769 - unable to get control of required module.
This error occurs, like I said, randomly.
I have only TXD, RXD and GND connected to the microcontroller. RTS and DTR are grounded. CTS, DCD and RI are floating. Communicating direct to the ATMEL thru TTL level.
The problem is this random occuring error.
If I use a 1800MHz chip, which I do not have to change band, everything works perfectly fine. All other AT commands respond perfectly. Using autobaud, at 9600.
Any ideas???
Thanx.

did you search for error in simcom document?

is it coming in format "+CME ERROR: 769"?? if yes then check AT manual for SIM340 it must have explained the reason for this error.

Hi there Ajay.
Thank you for the promptness in your answer.
Yes: the error comes in that exact same format. The problem is the AT Manual, that has only one single line (page 170) of a table with "unable to get control of required module" in the columm in front of error 769. Nothing else, nothing more.
Still have no ideas...

May not be important, but the SIM340DZ pdf gives strings such as
"DCS_MODE" as the expected parameter to AT+CBAND=

What happens if you try again ?

Hello ExperimenterUK,
I was just lazy to write the whole phrase out in my post.
I'm using the complete command "AT+CBAND="GSM850_PCS_MODE".
Anything different than the commands supported will result in error 765.
The error I'm getting here is 769 - unable to get control of required module.

Just for the records: I tried with a different module; I tried with an external power supply directly to the module (just for the records inside the just for the records, the power suply I used is an adjustable one, and when voltage was at 3.4V, the module sends a string of UNDERVOLTAGE WARNING. It's not important for my error since I'm using 4.0V, but has no documentation of this in any of the datasheets or application notes). All of the above gave the same error.

I suppose it's some hardware or floating pin I'm missing, since I cannot repeat this error on the eval board.

Maybe important: the SIM_RST, SIM_DATA and SIM_CLK are directly connected to the 6 pin sim card holder. I really don't remember why and the reason it was routed directly without the 22R resistors. Not using the SMF05C either.

News from the front: I got a new module; soldered wire strips on each pad, one by one and tested on a breadboard.Guess
What happened? Guess????

Nothing. No error...