Discussion in "Project Help" started by    cyberdyne    Jul 27, 2007.
Tue Sep 04 2007, 10:06 pm
#41
hi friend
i found out the signals which are required for the communication.the signal r
1.DCD(data carrier detect)
2.Tx,Rx,GND
3.RTS signal.
rts signal is required by the phone for communication.how to interface these signals when doing with a controller.Tx,Rx,and gnd will be from controller and abt the rts and dcd how to produce them.moreover in
rs232 communication logic 1 is represented by -3to-12V and logic 0 by 3to12V.is it only for data or the control signlas also
Wed Sep 05 2007, 12:19 am
#42
the handshaking signals i.e. RTS and DTR use a voltage level of TTL i.e. 0 and 5V
but DCD use RS232 voltage levels.. where high is in between -15 to -3 and low between +15 to +3 so.. if you want to make DCD high.. then you need to connect it to -ve voltage.. which you can get from Pin 6 of MAX232 (named as -V) and for making it low you can connect it to Pin 2 of MAX232 (named as +V).
I think that solves the problem now

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