S32K116 Reset issue

[asd046012]

Hello

    I meet a issue: the reset signal could not reset MCU.

    when I measued the pin reset, find that The voltage of the reset signal is 1V and the time is 500us,and the supply voltage of MCU is 5V.

    But I see the datasheet the range of low voltage  is 0-0.3VDD,so the I and hardware engineer all think the hardware design meet with the datasheet.

    so what is the requirement of the reset signal of MCU s32k116? could you tell me the corrent answer? 

[asd046012 · Accepted solution]

This issue has been solved, the pull-up resistance 22K has been replaced to resistance 22 by supplier, cause the level to not be low.

 I have used the resistance 22K to replace the resistance 22,the reset signal is normal.

[asd046012]

Hello  Robin_Shen

    I see this file,  our system use 24MHz bus clock,  so I think 500us absolutely fit with time requirement of signal reset,  the low voltage is 0-0.3VDD(0-1.5v),the voltage also fit with the datasheet. Reset circuit is as below, signal reset_sbc is the input signal reset.

    So could you give me any advice?

Reset circuit

[Robin_Shen]

I am a little confused what is the role of BAT54W here. Will it works if you remove D0102?
As I know the reset_sbc and RESET_MC1(PTA5) are bidirectional.

[asd046012]

Hello

   Sorry for the delay response. We have removed the Resistance 470 and BAT54W, and tested the reset signal again, find that SBC reset signal is normal, the MCU reset signal is not correct. please see the attachment.

    For the reset circuit  how to modify it?

[Robin_Shen]

Could you please show me the signal waveform of TP0101 measured with an oscilloscope?
And please show the SBC circuit (including the RESET_SBC part)

[asd046012]

Hello

   The wave of reset signal measured by oscilloscope is as below.

    The signal RESET_SBC is input signal for the MCU,  and output by SBC,  so the reset signal is controlled by SBC.

[Robin_Shen]

Hi asd046012,

Please refer the "5.2 RESET system" of AN5426, Hardware Design Guidelines for S32K1xx Microcontrollers

After flash program into the MCU, this phenomenon will no longer appear on the reset line.

Best Regards,
Robin
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