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USB Device interrupt status register - LPC2478

Tamiryan Michael

Hello,

Using a LPC2478, I'm trying to maintain a CDC connection with a host. But at a certain point, the RTX USB tasks are no longer signaled because both the EP_SLOW and EP_FAST bits of USBDevIntSt register remain 0 (the register having the value 0xF1). Do you know how this register is set? Can this failure be attributed to the device driver on the host?

Parents
  • 0 in reply to Tamir Michael

    "query device relations (removal relations)" on Windows is issued to the device driver,
    - when device is plugged off from USB port - surprised removal
    - when unrecoverable error occurs on the device or on the PC device driver.

    In both cases, it is detected by PC application as device disconnection.
    As of detection of connection/ disconnection over usbser.sys, see this post.

    tech.groups.yahoo.com/.../43461

    When the PC app detects disconnection of CDC device, it closes COM port handle immediately, so that Windows dispose the device driver object.

    If the disconnection is caused by plug-off, plug-in by user recovers the connection.
    - Device gets enumeration again on plug-in. You may need to initialize the USB communication context (variables and flags, etc) in Set_Configuration handler.
    - PC app has to detect connection, as described in above post, and it opens COM port again.

    If the disconnection is caused by error such as noise, soft-detach / attach on the device recovers the connection.

    If you often see connection error, noise source may lie on the board.

    Tsuneo

Reply
  • 0 in reply to Tamir Michael

    "query device relations (removal relations)" on Windows is issued to the device driver,
    - when device is plugged off from USB port - surprised removal
    - when unrecoverable error occurs on the device or on the PC device driver.

    In both cases, it is detected by PC application as device disconnection.
    As of detection of connection/ disconnection over usbser.sys, see this post.

    tech.groups.yahoo.com/.../43461

    When the PC app detects disconnection of CDC device, it closes COM port handle immediately, so that Windows dispose the device driver object.

    If the disconnection is caused by plug-off, plug-in by user recovers the connection.
    - Device gets enumeration again on plug-in. You may need to initialize the USB communication context (variables and flags, etc) in Set_Configuration handler.
    - PC app has to detect connection, as described in above post, and it opens COM port again.

    If the disconnection is caused by error such as noise, soft-detach / attach on the device recovers the connection.

    If you often see connection error, noise source may lie on the board.

    Tsuneo

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