Problem with connecting GSM sim300 and AVR ATmega8

[khosravi.ma00]

gsm sim300 and avr

hello .
I need help you . can you help me?
I buy a evb of sim300 and I want conect this to atmega8.
I can conect this to pc and send atcommand and recive answer.
I write program for atmega8 with codevision and I simulate this code with com port in proteus and answer this . this mean my prog is correct .
but connect this micro to evb sim300 and can't answer.
this mean my circuit is not correct .
this link is datasheet of my evb sim 300.
**broken link removed**

can you help me ?
i need a schematic for this project .

 

[fiolin]

Re: gsm sim300 and avr

Try with this circuit, perhaps micro to modem interfase are your problems.