USB double trouble

That's a bit like saying:

"I'm playing all the right notes - but not necessarily in the right order."

(Taken from Eric Morecambe, 1971.)

That's a bit like saying:

"I'm playing all the right notes - but not necessarily in the right order."

(Taken from Eric Morecambe, 1971.)

I'm playing all the right notes - but not necessarily in the right order

you have no idea ;-)

> I see that when I try to resend something to the device, a setup stage is triggered. Why is that?

Sound like the CDC device driver try to reset the device USB engine, by sending bus reset.
After bus reset, re-enumeration occurs. Even if the endpoint is stalled, it is released on the enumeration.

As it doesn't recover your problem, it means that your firmware doesn't implement USB_Configure_Event() properly. USB_Configure_Event() is called when Set_Configuation request comes on enumeration.
In this subroutine, your firmware should initialize the variables and flags which relate to USB communication.

For example, suppose that you have a buffer to receive large data from an OUT endpoint.
The buffer pointer is initialized to point to the top buffer in USB_Configure_Event().
Also, your firmware have any status flags related to communication, the flags are also initialized.

[code]
usbuser.c

#if USB_CONFIGURE_EVENT
void USB_Configure_Event (void) {

if (USB_Configuration) { /* Check if USB is configured */
[b] /* add your code here */[/b] }
} #endif
[/code]

Above suggestion is told just for recovery.
The original source of the trouble is still under question.

> but money still talks :-)

Call for demonstration of the analyzers to the representatives :-)

Tsuneo

Tsuneo,

Thanks for your reply. I have found the cause: the UART interrupt changing a global variable caused the CDC device to fail to reply sometimes ! Thanks a lot for your advise!