topic S32K116 Reset issue in S32K

S32K116 Reset issue

asd046012 — Tue, 24 Nov 2020 07:29:25 GMT

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?

Re: S32K116 Reset issue

Robin_Shen — Wed, 25 Nov 2020 03:20:55 GMT

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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Re: S32K116 Reset issue

asd046012 — Wed, 25 Nov 2020 06:18:44 GMT

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

Re: S32K116 Reset issue

Robin_Shen — Fri, 27 Nov 2020 02:29:22 GMT

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)

Re: S32K116 Reset issue

asd046012 — Fri, 27 Nov 2020 06:32:23 GMT

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.

Re: S32K116 Reset issue

Robin_Shen — Tue, 01 Dec 2020 08:33:14 GMT

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.

Re: S32K116 Reset issue

asd046012 — Wed, 09 Dec 2020 03:37:02 GMT

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?

Re: S32K116 Reset issue

asd046012 — Thu, 10 Dec 2020 05:34:53 GMT

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.