MKE04Z8 continuously restarts

[jankowalski]

Hi,

I have recently build some solution based on MKE04Z8 (TSSOP16). Unfortunately it doesn't work correctly. I can program it with no error but after program uC continously restarts even if I insert only for loop which increments simple variable.

P.S I work on internal clock with FLL (at the moment not configured).

[david_diaz]

Hello Jan,

Any update about your issue?

You can refer to the System Reset Status and ID Register (SIM_SRSID) in order to know the cause of the Reset.

You can find more information at Chapter 12.2.1 from the reference manual at:

www.freescale.com/files/microcontrollers/doc/ref_manual/MKE04P24M48SF0RM.pdf

I hope this information will be useful for you.

Have a great day.

David

[briancavanagh]

Hi David, I ordered a few PCB's and soldered on the MKE04Z8VTG4 and was experiencing resets on Pin 1.

At first I was thinking it was something within my circuits on the board.  What I did to confirm this was remove all components connect to the MKE04Z8VTG4  with the exception of:

1. Decoupling cap between pins 3 and 4 (I'm providing 5Vdc)

2. RC circuit at Pin 1 (PTA5), R=10k and C=.1uF.

The signal appears as a "Sawtooth" at a frequency of 5.435kHz.  The DC offset is 2.26Vdc with a ramp of 720mV, and then returns to 2.26Vdc, and then repeats.  Can you assist me with this or direct me to someone who can?

Thank you,

Brian

[mjbcswitzerland]

Brian

This behavior is typical of a board that has no software loaded to it - although the frequency is more like 250Hz.

Faster reset cycling can be due to the watchdog being incorrectly initialised, leading to a faster reset cycle.

Remember that the watchdog is enabled by default and if it is not disabled/configured/re-triggered within 4ms it will reset, which pulls the RESET pin low. Then the input will ramp up again due to the R/C.

If the watchdog disable/configure routine does something wrong the watchdog will also fire (faster) and thus cause a faster saw tooth signal to be generated.

Regards

Mark

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[mjbcswitzerland]

Hello Jan

Check the reset status register after the processor restarts in order to see the reason for it.

Regards

Mark

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