USB CDC (Serial) write on Leonardo is blocking. [imported]

[cmaglie]

This is Issue 948 moved from a Google Code project.
Added by 2012-06-06T13:34:31.000Z by [email protected].
Please review that bug for more context and additional comments, but update this bug.

Original labels: Type-Defect, Priority-Medium, Component-Core

Original description

From Mike King on the developers list:

"Serial_::write uses the function USB_Send to send data. USB_Send is a
blocking function. Is there away to make the virtual serial
connection non-blocking like it was on the Uno? I need to read from
the ADC a 1000 times per second and send the result to a computer for
processing. I measured the virtual serial bandwidth to be between 40
and 45 kBps on the Leonardo. I like to measure the voltage once per
1ms with the smallest "jitter." If I use a blocking write function
then I won't be sampling the ADC a 1000 times per second."

[NicoHood]

Actually it is not blocking and this causes another issue:
#3946

[sandeepmistry]

Closing, as @NicoHood mentioned, it does not block (anymore).