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Class specific requests in USB to Serial converter

Harshil Soni

Hi all,

Presently I'm working on USB to Serial device converter. For that I need to feed different class specific discriptors' data like Abstract Control Management Functional Discriptor, Call Management Functional Descriptor, Header Functional Descriptor and Union Functional Descriptor in enumeration process.

I've set a value of 0x07 in Abstract Control Management Functional Discriptor's bmCapabillities bitmap field, which indicates that my configuration supports SEND_BREAK, SET_LINE_CODING, GET_LINE_CODING, SET_CONTROL_LINE_STATE, SET_COMM_FEATURE, GET_COMM_FEATURE, CLEAR_COMM_FEATURE and SERIAL_STATE requests.

When I connect realterm/hyperterminal to my virtual com port, I'm getting SET_LINE_CODING, GET_LINE_CODING and SET_CONTROL_LINE_STATE requests except SEND_BREAK, SET_COMM_FEATURE, GET_COMM_FEATURE, CLEAR_COMM_FEATURE and SERIAL_STATE.

So, just want to know that how I'll get these remained class specific requests while data transmission from USB to Serial or Serial to USB?

In USB to Serial converter, there is an interrupt endpoint(notification element) through which I need to pass status notifications to the host. How I can send status notifications to the Interrupt endpoint? Is there any format/sequence to send the notification? How many data I need to send through?

(Note : There isn't any exact information mentioned in USB Communication Device Class spec for data format/sequence and no. of bytes which I need to send through notification element/interrupt endpoint)

Thanks in advance.

Harshil

Parents
  • 0 in reply to Chinzei Tsuneo

    Tsuneo, first of all thanks a lot for your response!

    Now, I'm sending 10 bytes in SERIAL_STATE notification and also getting DCD and DSR's status(according to their bitmap values) in the realterm which I've connected to my Virtual COM port with hardware flow control ON. But whenever I send bBreak or any error bit as 1 in UART State Bitmap, I'm not getting any status in the same realterm.

    So, I do have few questions regading it :

    SERIAL_STATE is a notification of UART which I'm sending to the USB. I would like to know that how USB's serial driver usbser.sys will respond to all these states of UART which I'm sending to it whenever hardware flow control is ON?

    In case of hardware flow control is ON, is it possible to control data flow from USB to serial by sending UART's notification?

    Harshil

Reply
  • 0 in reply to Chinzei Tsuneo

    Tsuneo, first of all thanks a lot for your response!

    Now, I'm sending 10 bytes in SERIAL_STATE notification and also getting DCD and DSR's status(according to their bitmap values) in the realterm which I've connected to my Virtual COM port with hardware flow control ON. But whenever I send bBreak or any error bit as 1 in UART State Bitmap, I'm not getting any status in the same realterm.

    So, I do have few questions regading it :

    SERIAL_STATE is a notification of UART which I'm sending to the USB. I would like to know that how USB's serial driver usbser.sys will respond to all these states of UART which I'm sending to it whenever hardware flow control is ON?

    In case of hardware flow control is ON, is it possible to control data flow from USB to serial by sending UART's notification?

    Harshil

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