Slow enumeration for USB 2.0 full speed device.

Hello,

I have LPC2368 controller which supports USB 2.0 full speed device.

While enumeration, I noticed the below request sequence
from Host to device:

1. Device Descriptor
2. Set Address
3. Device Descriptor
4. Device Configuration
5. String descriptor
6. String descriptor
7. Device Configuration
8. Device Qualifier
9. String descriptor
10. String descriptor
11. String descriptor

Since my device is 2.0 full speed device so I returned request error by setting status to STALL for Device Qualifier request.

But the problem I am facing is, that the device receives next request(i.e step 9 string descriptor) after a delay of 4-5 seconds.

That makes enumeration very slow and takes around 7 seconds to complete it.

Could anybody suggest me any solution to solve this.

Thanks.
VAIGO

Parents
  • "Since my device is 2.0 full speed device so I returned request error by setting status to STALL for Device Qualifier request.

    It's fine. Supposed response.

    "But the problem I am facing is, that the device receives next request(i.e step 9 string descriptor) after a delay of 4-5 seconds."

    It should be clarified if this problem is caused by the device side or the PC side.
    a) Which OS are you working on? Windows? XP or Vista? Which SP?
    b) Which example are you making up your device on?

    Tsuneo

Reply
  • "Since my device is 2.0 full speed device so I returned request error by setting status to STALL for Device Qualifier request.

    It's fine. Supposed response.

    "But the problem I am facing is, that the device receives next request(i.e step 9 string descriptor) after a delay of 4-5 seconds."

    It should be clarified if this problem is caused by the device side or the PC side.
    a) Which OS are you working on? Windows? XP or Vista? Which SP?
    b) Which example are you making up your device on?

    Tsuneo

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