TM4C123GH6PM: Device Descriptor Request Failed

Shitij Avlani

Part Number: TM4C123GH6PM

Hi,

I am using the USB library for an application with it being configured as a CDC device. I have followed all of the steps mentioned in the USB library user guide and cross checked my code with the examples in tivaware. The USB device is recognized by the computer but it states an error of "Device Descriptor Request Failed". This error does not occur when I load an example code. I have cross checked both the programs and found no difference except at the application end.

How should I proceed?

Regards,

Shitij Avlani

over 8 years ago

0 Amit Ashara over 8 years ago

TI__Guru**** 244410 points

Hello Shitij

Can you please share the project for a visual check of the code? Also if the requirement is for a CDC class device, then why not use the existing code and modify the same for your application. Will save you time and effort.

0 Shitij Avlani over 8 years ago in reply to Amit Ashara

Prodigy 180 points

I have attached the project. As you will see I am using the existing libraries and code. For my application the USB configuration code has been collected from the example projects in tivaware with slight modifications made at the application level to suit my needs. I hope things will get a little clearer once you get a chance to look at the project.ECG_TM4C123GH6PM.zip

0 Shitij Avlani over 8 years ago in reply to Amit Ashara

Prodigy 180 points

UPDATE: I hadn't added the USB interrupt handler in the tm4c123gh6pm_startup_ccs.c file. After making the changes the device descriptor error has gone. It shows up as a com port in device manager but I cant seem to access or open it.

0 Amit Ashara over 8 years ago in reply to Shitij Avlani

TI__Guru**** 244410 points

Hello Shitij

Yes, indeed the interrupt handler is required for USB enumeration. If you want to use a COM port type device then you must use an application like TeraTerm or PuTTy.

0 Shitij Avlani over 8 years ago in reply to Amit Ashara

Prodigy 180 points

Hi Amit,

So the COM port is visible in device manger and it says that it is configured properly, but I cant seem to open it from teraterm or any hyperterminal for that matter. Teraterm doesn't even list the serial port that the usb device is connected to. Could you please help me out with this.

Regards,

Shitij Avlani

0 Amit Ashara over 8 years ago in reply to Shitij Avlani

TI__Guru**** 244410 points

Hello Shitij

Strange. Can you please send a snapshot of the Device Manager and the TeraTerm?

0 Shitij Avlani over 8 years ago in reply to Amit Ashara

Prodigy 180 points

Hi Amit,

I have attached the screenshot of the device manager. I couldn't take one for tera term as the drop down menu closes when I try to use the snipping tool. But COM4 as shown in the device manager doesn't show up in the list of serial ports on tera term. I also tried using other hyper terminals like serial oscilloscope, with the same results.

Regards,

Shitij Avlani

0 Amit Ashara over 8 years ago in reply to Shitij Avlani

TI__Guru**** 244410 points

Hello Shitij,

Can you override the Serial COM port driver coming from the Windows system with the Stellaris Virtual Serial port driver?

0 Shitij Avlani over 8 years ago in reply to Amit Ashara

Prodigy 180 points

Hi Amit,

Could you please explain the procedure to do it?

Regards,

Shitij Avlani

0 Amit Ashara over 8 years ago in reply to Shitij Avlani

TI__Guru**** 244410 points

Hello Shitij,

Right click on the USB device and remove the driver. The device should show a "?" for the driver. Then update it manually by pointing the driver file as the Stellaris ICDI COM port drivers.

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TM4C123GH6PM: Device Descriptor Request Failed