dovr error during usb transfer

[brian239955_stm1_st]

Posted on June 02, 2004 at 02:38

dovr error during usb transfer

[brian239955_stm1_st]

Posted on May 26, 2004 at 13:11

I am getting dovr errors during an IN transfer on endpoint 1. The error shows as a CRC error when viewed on a USB bus analyser.

Can anyone indicate the possible cause of these errors.

[alok2]

Posted on May 27, 2004 at 02:02

Pls use USB forum for these kind of questions.

if you can indicate which micro you are using & when can you see the CRC error ? if it when the device is answering or is it when the Host is sending the data ? In any case, pls check the USB lines are not placed on noisy tracks & they are of same length. if there are CRC errors, the communication shall be retired by both host/device.

[brian239955_stm1_st]

Posted on May 27, 2004 at 07:39

its using the ST7 device which is why I think it appropriate here

the error occurs in the data transfer in response to an IN request ie the device answering the CRC error is synchronous with the DOVR error, hence I suspect the DOVR is the root problem and the CRC error on the line merely a symptom

[alok2]

Posted on June 02, 2004 at 02:38

DOVR will be set when the device is not able to write to the USB buffers. In the firmware pls check that EP is NAK before writing the data on the EP buffers & making the EP as Valid. I think you are not doing it. Can you provide your code pls.

The USB forum is for all USB devices including ST7 devices.