FCCU EOUT control problem on MPC5746R

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FCCU EOUT control problem on MPC5746R

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allenlw
Contributor II

We use MPC5746R and FS6500 as our basic hardware combination. We try to config the FCCU EOUT mode to Bi-Stable since its the only way FS6500 recognise.

The thing is we config the EOUT0 and EOUT1 to GPIO mode, we can control these two pin state.

But we can't control the EOUT1(not EOUT0) with error output mode.

Even by setting FOM to the TEST1 mode to driver both EOUT pin to high level, EOUT1 is still low.

We refer to the example https://community.nxp.com/docs/DOC-341616 MPC5746R FCCU Alarm State.

Still no luck.

We run out of options right now, so we need help to understand how to improve our code to achieve a right FCCU output curve.

Thanks.

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petervlna
NXP Employee
NXP Employee

Well, what to say.

You now must know how the bi-stable protocol works (I have posted it twice).

Ill do it one last time:

pastedImage_2.png

Looks like document of SBC chip is wrong and guys who wrote the document have no clue about FCCU safety protocols :smileyhappy: if they recommend this.

For some microcontrollers we have fixed multiplexer on FCCU EOUT pins so they always reflect bi-stable (reset) levels and there are no need of pull resistors. But this part for not designed for pure safety purpose like for example (MPS5744P), so you have to add (correctly) pull resistors.

Peter

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petervlna
NXP Employee
NXP Employee

Hi,

This is described in FS6500 ref manual:

pastedImage_1.png

Connect the pull up and pull down resistors to match bi-stable protocol when the micro FCCU EOUT pins are in high-z state.

IO_3 pull up to EOUT0

IO_2 pull down to EOUT1

pastedImage_2.png

Peter

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allenlw
Contributor II

Hi, peter,

I already have these two resistors, but still I can't control the EOUT1 pin.

So I config the two EOUT pins to idle pins not connected to the FS6500, use the test2 mode to control the EOUT pins.

The result is still EOUT1 out of control, but no the EOUT0.

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petervlna
NXP Employee
NXP Employee

Hi,

To control EOUT pin you have 2 possibilities.

1. install pull resistors

2. configure SIUL unit

during and after reset EOUT pins are in high-Z state until they are configured in SIUL module. This is behaving for SBC chip as fault state.

So if you install pull resistors in EOUT you must see during reset a high and low level on those pins corresponding to Normal state of FCCU.

pastedImage_2.png

This mean EOUT0 --> pull up   and EOUT1 --> pull down.

Just measure EOUT with scope or multimeter to see if during reset and before SIUL configuration EOUT pins has correct voltage level.

You dont need any SW in micro either to do this test.

Peter

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allenlw
Contributor II

Hi, peter

    I fount something inconsistent.QQ图片20181221095345.png

Here is some screen shot I took from safety manual for FS6500 and FS4500.

From this pic, FCCU_F0 connect to the IO[2], FCCU_F1 connect to the IO[3].

So, instead of a normal reset level, we have a error reset level. I wonder if this is the reason I have a problem controlling the FCCU EOUT.

Does this mean this document is wrong?

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petervlna
NXP Employee
NXP Employee

Well, what to say.

You now must know how the bi-stable protocol works (I have posted it twice).

Ill do it one last time:

pastedImage_2.png

Looks like document of SBC chip is wrong and guys who wrote the document have no clue about FCCU safety protocols :smileyhappy: if they recommend this.

For some microcontrollers we have fixed multiplexer on FCCU EOUT pins so they always reflect bi-stable (reset) levels and there are no need of pull resistors. But this part for not designed for pure safety purpose like for example (MPS5744P), so you have to add (correctly) pull resistors.

Peter

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allenlw
Contributor II

Hi,peter

I need your help with some more questions.

Before I said I can't control EOUT1 but not EOUT0, at that time, I use PI0 and PI1 as FCCU output pin.

Even though I adjust the pull resistors, the outputs don't change.

So I change the FCCU output pins to PJ0 and PJ1. This time I can't control EOUT0 but not EOUT1.

Then I config all these four pins, PI1 and PJ1 can have the right output not the PI0 and PJ0.

According to the IO_Signal_Description_and_Input_Multiplexing_Tables, there are seven FCCU output pins.

I wonder is there some other config rules that only certain FCCU output pins can work together, I can't find any information regarding this. But the experiment outcome suggest there is some connection.

So I wonder if you know something about this. ( I hope I have described my experiments clearly)

Thanks.

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zhouxx
Contributor I

兄弟,你解决了吗 我也遇到同样的问题了

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李丽丽
Contributor I

Have you find the way to control EOUT0 and EOUT1

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allenlw
Contributor II

@Zhou Xx  看我的问题,我开始是能控制0不能控制1,后来换了口能控制1不能控制0,最后我是尝试不同的组合(一共7个pin可以配),发现了一对可以输出的。。。所以我问peter这是怎么回事(最后一个问题)他没有答复我。

如果你们两只是想输出两路,希望我的回答可以帮助到你们。

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zhouxx
Contributor I

我已解决,已输出Bi-stable信号;感谢回复!

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zhouxx
Contributor I

你找到方法了吗,我现在也是EOUT1没法控制

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李丽丽
Contributor I

没有啊,我也在寻找解决方案,感觉跟手册里说的不太一样

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zhouxx
Contributor I

可以加个微信(13828777470)一起讨论下啊,互相沟通,这方面资料实在太少了。

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allenlw
Contributor II

Peter, thanks for you patient explanation, I will try to adjust the pull resistors and see if I can get this right.

Thanks again.

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