TMS320F28375S: TMS320F28375S usb_dev_serial example baud rate settings.

digvijay khambe

Part Number: TMS320F28375S

Respected sir,

I have successfully implemented the usb_dev_serial example and also integrated the USB related part in my coding. I am using only USB and not UART. I have modified code according to that. The drivers are given such that it opens COM port in windows PC.

So what i want to know is that how baud rate of VIRTUAL COM Port(USB Driver) can be set in firmware.

If i do not use getlinecoding() function what baud rate is used??

I tested my code with Terminal.exe software from PC. The even if i select any baud rate the same code was working for different baud rates. So why is this happening??

If there is fixed baud rate for usb_dev_serial without UART part example then what it is??

In general i want to understand the baud rate selection process for usb_dev_serial example without UART part and related drivers which open virtual com port.

Regards,

Digvijay

over 5 years ago

0 Sal Pezzino over 5 years ago

TI__Mastermind 32995 points

Hi,

There is no real baud rate since the communication is happening over USB.

sal

0 digvijay khambe over 5 years ago in reply to Sal Pezzino

Expert 2735 points

Respected sir,

So you mean to say that communication is happening on 1.5 Mbps or 12 Mbps, right?? Then what is the use of Getlinecoding() function which is called in control handler ??

Regards,

Digvijay

0 Sal Pezzino over 5 years ago in reply to digvijay khambe

TI__Mastermind 32995 points

The USB uses D+/D- differential data lines and at full speed operate at 12 Mbps. For more information, please review the USB protocol.

I am not sure exactly what that function is doing. You can read the source code. If you still need help on Monday I can look into this.

sal

0 digvijay khambe over 5 years ago in reply to Sal Pezzino

Expert 2735 points

Respected sir,

I have gone through the source code of usb_dev_serial but i am not able to understand the use of function mentioned in previous reply. I can not do anything else as i can not access source code in usblib.lib file.

The one more question is can as use this stack (usblib.lib) for other controller series for example F2810 with minor changes in library??

Regards,

Digvijay

0 digvijay khambe over 5 years ago in reply to digvijay khambe

Expert 2735 points

Respected sir,

Have you found anything on baud rate setting??

Regards,

Digvijay

0 Sal Pezzino over 5 years ago in reply to digvijay khambe

TI__Mastermind 32995 points

The Getlinecoding function does not do anything useful in this example. It merely demonstrates how to get the line coding. You do not need this code.

You will see the example does not use it since the line coding is stored in pvMsgData, but this variable is not used usefully in the code.

sal

0 digvijay khambe over 5 years ago in reply to Sal Pezzino

Expert 2735 points

Respected sir,
Thanks for the quick reply.
Please reply asap, its urgent.
As there is nothing in the software to determine baud rate of the USB and the bits which indicates the baud rate work only in host mode,
I decided to use scope to observe the waveform. On scope i observed the wave form of 6 Mhz.
So is 6 Mbps is the baud rate??
If 6 Mbps is baud rate, can i say that USB works on non standard baud rates(other than 1.5 Mbps and 12 Mbps)???

Regards,
Digvijay

0 digvijay khambe over 5 years ago in reply to Sal Pezzino

Expert 2735 points

I have attached snap of scope.

0 Sal Pezzino over 5 years ago in reply to digvijay khambe

TI__Mastermind 32995 points

The bit rate at full speed is 12 Mbps.

As a CDC is a virtual com port, and thus has a virtual baud rate. Therefore, I am very confused by your question.

Please see some of these searches using a common internet browser:
www.google.com/search
os.mbed.com/.../
community.st.com/.../how-set-usbcdc-virtual-com-port-baudrate
electronics.stackexchange.com/.../importance-of-baud-rate-in-usb-cdc
www.microchip.com/.../m285533.aspx

Thank you. And have a good day.
sal

0 digvijay khambe over 5 years ago in reply to Sal Pezzino

Expert 2735 points

Respected sir,

I have gone through the links suggested by you. From that i can conclude that line coding is not considered by USB. USB uses its own data rate. But i am still not able to figure out what is that data rate. For now i am closing this thread. I have some other issues regarding device receive errors but i will be opening new thread for that.

Regards,

Digvijay

0 Sal Pezzino over 5 years ago in reply to digvijay khambe

TI__Mastermind 32995 points

Please click on one of my responses to close the thread.

sal

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TMS320F28375S: TMS320F28375S usb_dev_serial example baud rate settings.