TM4C123GH6PM: USB Peripheral Initialization

Pranjal Shrivastava

Part Number: TM4C123GH6PM

Hi,

I was reading through the TivaWare USB Library, for debugging something. While going through I came across the USBClockEnable( ) function.

Looking at what this function does, I see it's writing to a register USB_O_CC or USB Clock Configuration Register, which is at the offset of 0xFC8 from the USB0 base address.

I verified that from the header file hw_usb.h (attached screenshot)

USBClockEnable()

hw_usb.h

But on examining the reference manual/datasheet and also the device header file provided by Keil, I saw no such register. The last register was USB Peripheral Properties as per both.

Is this a hidden register that is being configured? Or am I using the wrong library version and getting stuck due to that?

Please give some insight.

Thanks

Pranjal

over 4 years ago

0 Chester Gillon over 4 years ago

Guru 92251 points

Pranjal Shrivastava said:
Or am I using the wrong library version and getting stuck due to that?

The description of USBClockEnable() in the TivaWareTM Peripheral Driver Library USER’S GUIDE contains the following:

Note:
The ability to configure the USB PHY clock is not available on all Tiva devices. Please consult the data sheet for the Tiva device that you are using to determine if this feature is available.

Table 36. USB TivaWare for C Series Available Functions and Parameters in the Differences Between Tiva™ C Series TM4C Microcontrollers shows that the USBClockEnable and USBClockDisable functions are only for TM4C129x devices. I.e. not for use on your TM4C123GH6PM device.

0 Pranjal Shrivastava over 4 years ago in reply to Chester Gillon

Prodigy 210 points

Hi Chester,

Thanks for this! I just checked it. Also, that means by just clearing the USBPWRDN bit in RCC2, I can fire up the clock for USB on my TM4c123GH6PM device, right?

Regards,

Pranjal

0 Bob Crosby over 4 years ago in reply to Pranjal Shrivastava

TI__Guru 72500 points

Chester,

Thank you for jumping in and helping.

Pranjal,

In addition, from page 1113 of the datasheet:

0 Pranjal Shrivastava over 4 years ago in reply to Bob Crosby

Prodigy 210 points

Thank you so much Bob, just looked it up! :)

This community is really good!

Thanks & Regards,

Pranjal

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TM4C123GH6PM: USB Peripheral Initialization