hi Abhishek !

it's the same way i am having the connections on modem side. i have shorted the RTS-CTS and DTR-DSR pins on modem side and i am using Tx , Rx and GND only from MC side.

Now the crystal which i am using is of frequency 22.1184 MHz. The baud rate i am trying to achieve is 115200 ( 57600 * 2 ). I've set the SMOD bit in the PCON register. i am using this setup for transmitting data to the PC i.e.( MC connected to COM port ). When i try to transmit the characters from MC.. i don't see any result on the hyperterminal set at 115200 baud rate. But the same program and connections , display the characters on the hyperterminal when connected at baud rate of 9600 ( PCON = 00h ).

i am also taking the care of terminating the command with CR.

Each time i send the command 'AT' to the DCE. When MC connected to the COM port i can very well see 'AT' displayed on the hyperterminal provided i am communicating at 9600. But the same program fails to display 'AT' at any baud rate higher than 9600.

Now the 2nd problem is of getting an 'OK' response. Even if i am able to send 'AT' to the modem ( which i can easily verify by communicating with COM port of PC ) i am not able to receive 'OK' response... even at 9600 baud. Also if i try to dial the modem by command
'ATDP215' ( 215 being the extension no. ) i don't get any carrier detect signal or no dialing tone can be heard.

i've used the polling method for transmitting and receiving the character.

thanks.

kunal.