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TM4C1294NCPDT: TivaWare version 2.1.4.178

BocaDev
Intellectual 720 points
Part Number: TM4C1294NCPDT

I have been looking into upgrading my older TM4C1294 project from using Tivaware version 2.1.3.156 to the latest, and what looks like the final, Tivaware version 2.1.4.178.

While investigating, I noticed while looking at the USB Bulk example in the later TivaWare, the source code has these new lines of code added as compared to the USB Bulk example in the older version.

// Tell the USB library the CPU clock and the PLL frequency. This is a
// new requirement for the TM4C129 devices.
//
SysCtlVCOGet(SYSCTL_XTAL_25MHZ, &ui32PLLRate);
USBDCDFeatureSet(0, USBLIB_FEATURE_CPUCLK, &ui32SysClock);
USBDCDFeatureSet(0, USBLIB_FEATURE_USBPLL, &ui32PLLRate);

Can someone explain what the "new requirement for the TM4C129 devices" mean? What is met by "new requirement"? I have been using the USB for several years without any issues in the older version.

Also how does this effect the ROM_UpdateUSB function built-into the silicon? Is it now a requirement that these three function-calls be added before entering the ROM function?

Thank you,
Alan

  • 0
    TI__Guru 72500 points

    This is a result of the workaround provided for erratum SYSCTL#22. The workaround configures the PLL frequency as 240MHz instead of 480MHz when using a 120MHz system clock. The modification in ConfigureUSBInterface() uses a new function to read the PLL frequency and uses the actual value when configuring the USB. When calling ROM_UpdaterUSB() from an application, the function ConfigureUSBInterface() must be called first. The "ROM_" version has been deprecated and if called will result in an undefined symbol error with version 2.1.4.178. 

  • 0 in reply to Bob Crosby
    Intellectual 720 points

    Hi Bob,

    Thanks so much for your speedy response.

    It looks like if I were to follow the various examples in the Tivaware version 2.1.4.178, I should be okay with the update. That is, if I come across an issue I need to investigate within the Tivaware 2.1.4.178 folder. I should have started there first, sorry.

    Thanks again Bob for you excellent support!

    Alan