MKE04Z8VWJ4 negRESET driven low but reset pin disabled

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MKE04Z8VWJ4 negRESET driven low but reset pin disabled

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iamarcoia
Contributor II

Good morning,

I have a problem and i don't know how to solve:

in a custom board i'm using MKE04Z8VWJ4 programmed with codewarrior.

the reset pin PTA5 i use it as input I connect a resistence divider 1k and 1k and a cap 100nF and a zener 5,1 V to protect, normaly the input is low.

When I power on the board and the controller doesen't work (i connect 7 segment to other output and doesen't works), seems to enter in a strange mode, when i press the button i drive to 1 the input and the microcontroller wakes up ad run normaly.

If i disconnect the resistence that drive low the input, this strange behavior doesen't appeare.

How can i solve the issue by software?

pastedImage_1.png

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1 Solution
1,154 Views
kerryzhou
NXP TechSupport
NXP TechSupport

Hi Marco Iannelli,

   The KE series is special, even you disable the reset pin, but after POR reset, the PTA5 pin functions as reset, until you load the SIM_SOPT0 in the code, then your reset pin function will be disabled, and work as other function.

  pastedImage_1.png

      So, you must make sure, during POR reset, you need to keep the reset pin high, otherwise, your chip will work abnormal.

Wish it helps you!

If you still have question about it, please kindly let me know.

Have a great day,
Kerry

 

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi Marco,

   What do you mean to 8V or open mean in your picture?

   The KE04  reset pin need to add 4.7K to 10K external pull up resistor and 0.1uf capacitor.

  You can't add the pull low resistor, otherwise your reset pin signal is not correct, it will influence the mk04 normal working.


Have a great day,
Kerry

 

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iamarcoia
Contributor II

Hi Kerry thank you for your help,

the reset pin is disabled via processor expert, I test other board with MC9S08QG8CPB and this strange behavior not appear if I disable the reset pin it remain inactive in MC9S.....

When I power on the board and the controller doesen't work (i connect 7 segment to other output and doesen't works), seems to enter in a strange mode, when i press the button i drive to 1 the input and the microcontroller wakes up ad run normaly.PTA5 IS SET LIKE INPUT NOT RESET. After the first push the input run correctly like input ant other output are activated and run correctly.

I mean:

pastedImage_1.png

have a nice day

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kerryzhou
NXP TechSupport
NXP TechSupport

Hi Marco Iannelli,

   The KE series is special, even you disable the reset pin, but after POR reset, the PTA5 pin functions as reset, until you load the SIM_SOPT0 in the code, then your reset pin function will be disabled, and work as other function.

  pastedImage_1.png

      So, you must make sure, during POR reset, you need to keep the reset pin high, otherwise, your chip will work abnormal.

Wish it helps you!

If you still have question about it, please kindly let me know.

Have a great day,
Kerry

 

-------------------------------------------------------------------------------
Note:
- If this post answers your question, please click the "Mark Correct" button. Thank you!

 

- We are following threads for 7 weeks after the last post, later replies are ignored
Please open a new thread and refer to the closed one, if you have a related question at a later point in time.
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