Reading DSR and CTS in MCUXpresso USB stack

[ugljesa_tomanov]

Hello,

We are using USB port on K28 to communicate with a modem in CDC mode. Is it possible to read the state of simulated CTS and DSR lines in MCUXpresso USB stack?

Thanks

Ugljesa

[ugljesa_tomanov]

Hi Felipe,

Yes, our device is host. The idea is to use RTS-CTS synchronization with modem.

Regards

Ugljesa

[ugljesa_tomanov]

Hi Felipe,

Thank you on your answer.

If I understand correctly function USB_HostCdcSetAcmCtrlState is controlling the output lines (RTC and DTR). We need to detect changes in the input line state. USB_HostCdcGetAcmLineCoding function is used to get DSR state but I am not able to find how to detect CTS.

Best regards

Ugljesa

[FelipeGarcia · Accepted solution]

Hi Ugliesa,

Unfortunately, that is not possible, I recommend you to check also the SerialState this contains the current state of carrier detect, transmission carrier, break, ring signal, and device overrun error. Please check below snippet from PSTN specification (document attached).

I hope this is helpful.

Best regards,

Felipe

[ugljesa_tomanov]

Hi Felipe,

Thank you very much for your answer.

Best regards

Ugljesa

[FelipeGarcia]

Hi Ugliesa,

Please check USB_HostCdcTask in host_cdc.c, in kUSB_HostCdcRunGetStateDone you set the control state.

USB_HostCdcSetAcmCtrlState function implements CDC ControlLineState request.

Hope it helps!

Best regards,

Felipe

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[FelipeGarcia]

Hi Ugliesa,

Are you using USB stack as host or device?

Regards,

Felipe