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8 years, 11 months ago.

transmission speed in USB virtual serial port through USBDevice library

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 mbuino platform to PC. The microcontroller has support for USB, and currently I am transmitting data by creating a virtual serial port using USB CDC (using the library USBDevice provided by the mbed.org). 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??

1 Answer

indira m
7 years ago.

1. In this context, baudrate setting is meaningless; I hope you have connected via USB cable to PC; It is just a "virtual" COM. Settings are valid only if you use any hardware like usb to serial adapter.

2. Transfer speed goes upto the maximum rate guaranteed by Data Transfer Type under USB 2.0 (hope here you meant High speed)

3. For large amount of data, "Bulk Data transfer" with USB CDC is better.

Note: I know the post is 1 yr old; but i felt this answer may be helpful for others who visit this page.

Thanks, Your reply gives me support. But How can I send the data at high speed from the computer like VB.net. as COM port have very fixed baud rate. can I increase the baud rate what I want? 1.5MBps. Please reply.

posted by ashutosh bhat 22 Jun 2017

In the case of No-Serial-Converter in between PC and USB device controller, PORT settings are immaterial. Communication interface works with the speed of USB 2.0 specification.

posted by indira m 16 Jan 2018