S12ZVL96 MCU in stop mode can not be waken up by LIN communication but by GPIO interrupt.

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S12ZVL96 MCU in stop mode can not be waken up by LIN communication but by GPIO interrupt.

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ZhaiHui
Contributor II

Hello,

We are using S12ZVL96 MCU as a LIN slave. After entering STOP mode, it can not be woken up by LIN wakeup signal or LIN unconditional frames in normal schedule, no response sent. But once we trigger a GPIO interrupt, the LIN communication works again, responses are sent again. The most strange point is we can not reproduce this issue in our lab, and according to the log file got from vehicle, the schedule table is handled correctly by master. Is anyone can give some suggestions for further investigation? 

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ZhaiHui
Contributor II

Hello Stano,

Thank you for comment.

We found the cause of this problem. We were checking the LIN status by LP0DR_LPDR0 to confirm LIN wakeup. But as LP0DR_LPDR0 can not latch the low status of LIN bus. It depends on the timing of reading the LP0DR_LPDR0. For our development environment LP0DR_LPDR0 is always read at start bit of sync byte, so there is no problem. But in customer environment LP0DR_LPDR0 is always read at first bit of sync byte, which is high, so the problem happens.

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ZhaiHui
Contributor II

Hello Stano,

Thank you for comment.

We found the cause of this problem. We were checking the LIN status by LP0DR_LPDR0 to confirm LIN wakeup. But as LP0DR_LPDR0 can not latch the low status of LIN bus. It depends on the timing of reading the LP0DR_LPDR0. For our development environment LP0DR_LPDR0 is always read at start bit of sync byte, so there is no problem. But in customer environment LP0DR_LPDR0 is always read at first bit of sync byte, which is high, so the problem happens.

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StanoA
NXP TechSupport
NXP TechSupport

Hello Zhai,

It is hard to provide suggestion when it is not repeatable in lab. So try to measure the LIN to GND signal in lab and in vehicle by scope and compare it. As the LIN interface has three pins only (VLINSUP, LIN and LGND), please try check the right connection in vehicle.

I wish you success in your task.

Best Regards,

Stano.

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