alexxx
Advanced Member level 4
You mean that modem's Tx pin goes to AVR's Tx pin and Rx goes to Rx? Then you are right, it should not be like this. You must use a cross cable that sends pin 2 signal of one side to other's side pin 3 signal and vice versa. There is no way to communicate like you described. Have you tested with the multimeter the connection between modem and PC when you connect it with the PC? Are you using the same cable in both situations?drtvskuthsav said:Both my modem board and The controller board is having DB9 Female pins. So I thought of using DB9 Male pin - Male Pin Connector. But I checked how the pins of this connector are connected internally. When I tested with multimeter I found that Tx pin of one end of connector is connected to Tx at other end and Simlarly Rx-Rx connections. I think this should not be like this. Am I right? Could this be the problem?