transmission speed in USB virtual serial port

Question

What is the transmission speed or baud rate in a virtual serial port connection through USB 2.0 . I basically need to transfer data from an ARM microcontroller to PC. The microcontroller has support for USB, and currently I am transmitting data by creating a virtual serial port using USB CDC. On using minicom (in linux) or putty (in windows), I am able to receive data irrespective of the settings of baud rate in the application.

This gets me a little confused, as to who sets the data transfer rate and what is the significance of the settings in the application. What transfer speeds can I expect in this case, and is there any way to control and measure them?

Moreover, for streaming data and intermittently issue commands, is USB CDC a good solution??

Choreodrama

Answer 1

The "baud rate" that you set in your terminal program when connecting to a USB CDC ACM virtual serial port is just a number that gets sent to the device, and the device can ignore it or interpret it however it wants to. The baud rate does not affect the rate of data transfer over USB.

The rate of data transfer is determined by what USB speed you are using (low speed, full speed, high speed, etc.), how much other traffic is on the bus, how efficiently you are writing to the serial port on the sending side, and how efficiently you are reading on receiving side.

Chiffonier