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TM4C123GH6PM: TM4C123GH6PM USB features

Part Number: TM4C123GH6PM

In the USB library article "USB Device PLL Feature" given below

On some device classes, like the TM4C129x, the USB library must know what the application
is using for the main PLL since the USB controller uses this to generate the USB clock. The USB
library defaults to a 480 MHz PLL frequency, however, if this is not the case then the application must
call the USBDCDFeatureSet () function with the USBLIB_FEATURE_USBPLL option to inform the
USB library of the non-default PLL frequency.

question 1.1)  Is this valid only for TM4C129x? I am using TM4C123GH6PM.

question 1.2) If it is valid for TM4C123GH6PM then if I use PLL as  microprocessor clock source at 80MHz (Max speed) . Then do I need to inform USB library using USBDCDFeatureSet() function.

question 1.3)I above case is true , then USB will run at 80MHz.Am I correct?

In the USB library article  "USB Device ULPI Feature" given below

The TM4C129x class devices also supports using an external ULPI USB phy to allow operating
the USB controller in high speed mode. This feature is enabled by setting the USBLIB_
FEATURE_USBULPI option combined with the desired speed. From the applications perspective
this has no affect to normal USB operation other than the necessity to properly enable the
USB external phy pins.

Question 2.1 )  Is this valid only for TM4C129x? I am using TM4C123GH6PM.Is it possible to run USB at high speed in  TM4C123GH6PM?

  • Question 1.1, 1.2, 1.3,
    The default for the TM4C123 is 80MHz. If running at 80MHz there is not need to adjust the USBLIB_FEATURE_CPUCLK feature setting. See:
    C:\ti\TivaWare_C_Series-2.1.4.178\docs\SW-TM4C-USBL-UG-2.1.4.178.pdf section 3.2.2.2

    Question 2.1:
    The TM4C123 devices do not support the external ULPI USB PHY. That feature is only on the TM4C129 devices:
    www.ti.com/.../spma065.pdf