k64f reset_b pin is low right at the start and does not turn high

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k64f reset_b pin is low right at the start and does not turn high

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hunglam
Contributor II

Hi,

I have a problem with my self designed pcb which uses the k64f (100 pins) as the mcu. one pcb work just fine. however, the other one cannot be programmed via jtag because the  reset_b pin is permanently low. the reset line is connected to a power source via pullup resistor. I have verified that all decoupling capacitors are ok. If I connect the reset pin to a power source, the reset line stays high. thus there is no leak anywhere. however, if I turn on the k64, the reset pin is driven low and stays there. what is wrong???

hope someone can help!

thanks in advance

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1 Solution
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hunglam
Contributor II

Hi Pedro,

thanks for your advice. I have been busy with other works and couldn't reply earlier. the problem seemed to have been solved. I did a hard reset on the NMI reset pin, which brought the mcu back to life.

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vicentegomez
NXP TechSupport
NXP TechSupport

Hi Hung

Have you check that there is not any missing part on the board, also all the pins are properly solder.

If you have more K64 samples what happens if you place a new one on the failed board?

or if you can make a swap between the good board and the failed one, with this we can check the if the MCU is damage or if you have any problem with the board.

Regards

Vicente Gomez

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hunglam
Contributor II

Hi Pedro,

thanks for your advice. I have been busy with other works and couldn't reply earlier. the problem seemed to have been solved. I did a hard reset on the NMI reset pin, which brought the mcu back to life.

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