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Data abort right after NPORST enabling

Marek Polak8
Prodigy 120 points


Hello,

I am new in Hercules and ARM processors and I am facing for me weird behavior of processor . I have downloaded my program in procesor. After power up sequence -> 1.2V -> 3.3V and then NPORST processor jump into address 0x10, if I make another PORST or power up sequence, everything is same and processor jump on address 0x10 right after reset, no program is executed.

But if i connect small voltage on 3.3V branch of processor, processor starts normaly. (3.3V thru 5k resistor, it creates 1.5V on processors 3.3V power branch -> I discovered that, when I connected USB<>UART converter, because on communication lines there are pull up resistors).

If I check the start up sequence with oscilloscope, I believe it is ok and I really can´t see difference between case, when there is no power in the start of powering up sequence and when there is 1.5V. The sequence is the same (I mean times of starting voltage and PORST), only 3.3V branch doesn´t start from 0V, but from 1.5V. On the 1.2V branch is zero in both cases, I checked that.

Thank you in advance for your help

Marek

  • 0
    TI__Guru**** 197826 points

    Hello Marek,

    This is nPORRST timeing requirements:

  • 0 in reply to QJ Wang
    Prodigy 120 points

    Thank you, but I know this picture and it doesn´t explain my situation.

    On first two prinscreens you can see traces, when no external power is connected and processor then doesnt work and hit address 0x10.

    And here with external pull up. As you can see, there is no time difference, but processor now works fine.

    And here you can see, how our watchdog works, but if I start processor without external pull ups, processor doesnt start after that PORST pulse! I have to connect external power thru pull ups and turn power off and on. When I only connect external pull ups and make PORST, processor is still catch on memory position 0x10.

    Perhaps I am missing something. Please help. Thank you in advance

  • 0 in reply to Marek Polak8
    Prodigy 120 points

    When exception jump to address 0x10, in LR i have 0x12F40. => First instruction is on 0x12F38 = (0x12F40 - 8) and the first instruction is PUSH {R12, LR}. I am using IAR studio.

  • 0 in reply to Marek Polak8
    Prodigy 120 points

    I can´t find reason, why it is happening. I can hold manualy nPORST connected to GND and after connection of 3.3V and 1.2V disconnect the short circuit to GND and proccesor works only, if there was small DC voltage on 3.3V supply branch (1.5V). And if there was NOT any small DC voltage on 3.3V supply branch before i turned ON 3.3V and 1.2V, proccesor hits address 0x10 Data Abort and then I can make another PORST and nothing change (poccesor hits Data Abort). I am not shure, if I am explaining it enough? Please feel free to ask me any question about my problem.   

  • 0 in reply to Marek Polak8
    TI__Guru**** 197826 points
    Hello Marek,

    What is the value of the pull-up resistor and the capacitor on nPORRST signal? I feel the value of the cap and resistor is too big.