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Original question:

TM4C1290NCPDT: Question for Errata SYSCTL#23

TM4C1290NCPDT: Question for Errata SYSCTL#23

Koichiro Tashiro
Mastermind 22915 points
Part Number: TM4C1290NCPDT

Hi,

Suppose SYSCTL#23 happens, a bus fault is generated on reset.
In such case, if software detects the bus fault and the handler simply clear it, the system can operate properly afterward, correct?

Thanks and regards,
Koichiro Tashiro

  • 0
    TI__Guru**** 190806 points

    Hi,

      With the suggested workaround by using the newer TivaWare versions, I don't think you will get a bus fault. I've not come across any forum reporting that a bus fault is observed with the TivaWare versions after v2.1.3. There is no mention in the errata what will happen after the bus fault is generated and whether the processor can continue after the bus fault is handled. It is possible to see a repeated bus fault but I don't know for sure. The reason is that some internal register is not properly initialized resulting in the errata. Clearing the bus fault does not mean the un-initialized internal register will be initialized to a proper state. Please use the newest TivaWare SDK to address the issue rather than assuming clearing the bus fault will resolve the problem with an older TivaWare version. 

  • 0 in reply to Charles Tsai
    TI__Mastermind 22915 points

    Hi Charles,

    As I informed in the original post, the customer needs to use PLL bypass. This means OSCCLK source must be MOSC.

    Charles Tsai said:
    Please use the newest TivaWare SDK to address the issue rather than assuming clearing the bus fault will resolve the problem with an older TivaWare version. 

    Do you mean it is possible to avoid the bus fault to use the newest TivaWare SDK even if MOSC is used as OSCCLK source for SYSCLK?

    Thanks and regards,
    Koichiro Tashiro

  • 0 in reply to Koichiro Tashiro
    TI__Guru**** 190806 points

    Hi Koichiro-san,

    Koichiro Tashiro said:
    As I informed in the original post, the customer needs to use PLL bypass. This means OSCCLK source must be MOSC.

    If you look at the diagram shown in the errata, the highlighted in red is what caused the errata to occur. The MOSC ultimately becomes the SYSCLK if USEPLL is deselected.  I have highlighted in yellow to show the path from MOSC to SYSCLK. The workaround implemented in the newer TivaWare SDK is to address the issue for the affected path (highlighted in red). This means after the workaround, the path from MOSC -> OSCCLK -> SYSCLK will be fixed.