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TM4C1294NCPDT: How to Unlock PD7

Diljith k Anil
Prodigy 75 points
Part Number: TM4C1294NCPDT

I am using the TM4c1294NCPDT and in that controller the ,the 7th pin of port D was not able to program and came to know that this is a pin with special consideration which is configured as GPIO by default but is locked and can only be programmed by unlocking it. 

Will there be any problem in unlocking this PD7?
If No,how can i unlock this PD7 ?.

  • 0
    Guru 86605 points
    Hi Diljith,

    See, example unlocking code from the link below. But, it is for TM4C123 MCU.

    e2e.ti.com/.../1042023

    -kel
  • 0
    Guru 117855 points

    Note too that the "lesser" MCU (as mentioned by poster Markel) has "TWO Such Special Pins."    You must check your MCU Manual - to determine the number of such "Locked" Pins.    (W/in the MCU Manual - Search (via "Find") for "NMI."     (that's Non Maskable Interrupt)

    My firm has found it "wise" to unlock BOTH PINS ... as leaving one "stuck" in that restricted mode - in time - is SURE to yield torment!     Clearly - it proves more "professional" & efficient to, "Extinguish the Entire FIRE"   - and not just the, "Blaze du Jour!"

    Should the link provided be unclear - your use of the forum "Search Box" (high up on this page) enables you to enter your MCU's part number AND the keyword "NMI Unlock."    This should produce MULTIPLE posts - which will increase your understanding - (beyond) that of any (single) one.    (to your comfort - you cannot BREAK your device - by (even) a mistaken Unlock Attempt...   Yet ... I am told that an excess of  "Unauthorized  Criminal Release" - may produce (some) local,  "ill effects.")     (little - (very little) Monday a.m. humor tossed in...)

  • 0
    TI__Guru 72500 points

    First, thanks to Markel andCB1 for providing prompt answers over the weekend.

    Just to make it easier for others who lookup this thread in the future, I have edited your title and am providing example code specific to the NMI pin (PD7) of the TM4C1294 device.

        //Unlock the NMI pin, PD7
    //
    HWREG(GPIO_PORTD_BASE + GPIO_O_LOCK) = GPIO_LOCK_KEY;
    HWREG(GPIO_PORTD_BASE + GPIO_O_CR) = 0x80;

  • 0 in reply to Bob Crosby
    Guru 117855 points

    Good that Bob - and thank you - as well.

    Yet - would it not "MAKE GREAT SENSE" for poster to "UNLOCK BOTH NMI PINS?" (assuming that 2 such pins serve as "Default to NMI" - as they do upon the '123.)

    By "unlocking ONLY ONE" - the poster is "Vulnerable" to the limit imposed by that 2nd pin.   It is RARE (very) rare - that poster would deploy NMI deliberately - and should that be true - he/she would (surely) know the pin's location!

    May it be noted that,  "Posters Question or Issue" - rarely is blessed w/great experience - and deep thought?     Thus - the  "Helper Crüe's ability to ADD VITAL (yet absent) PARTS" - seems of High Value...