I want to access the GS64 integrated on CEPAGs GS64T via RS232 by the ATMEL ATMEGA128 microcontroller. Therefor I use a cable with four lines: Rx, Tx, RTS and CTS … it’s the only difference in communication to the PC I can imagine, where all lines are connected.
When I start the Modem, an initial “ATE2SDR?" is sent for checking the SIM-Status, if the presence of a SIM-card is reported, the PIN should be sent. Before sending, the MC asks which type of PIN is needed by sending an “AT+CPIN?” … and there the fun starts. The MC always gets ERROR back, if I try the very same commands by a PC based Terminal, everything is fine. All the other commands work well on the MC, the only commands working differently are “AT+CPIN?”, “AT+CPIN=“xxxx”” and as a try "ATE2SSN” Somehow commands related to the SIM-Card, except for “AT*E2SDR?” are corrupted when being used by the MC.
What might be the cause?