What if PCS is not used for LPSPI?

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What if PCS is not used for LPSPI?

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xu_wenming
Contributor II

Hello, 

On the SPI bus, there are only one master and one salve, chip select of slave device is tied to ground, that means slave device is always active, in this case, chip select of master is not necessary any more and we did not assign pin for it. 

We also use some constant-current LED driver (like TLC5928 of TI) which does not have chip select pin by design. 

The problem is PCS is mandatory to LPSPI module in S32DS.

Please kindly give your recommendation. 

Matthew Xu

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danielmartynek
NXP TechSupport
NXP TechSupport

Hello Matthew,

The selected PCS pin of the LPSPI module does not have to be routed to a PORT in the SDK driver for Pin Muxing.

BR, Daniel

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xu_wenming
Contributor II

Hello Daniel,

I'm not sure I get your point, do your mean I can select any of PCS without configuring anything in Pin Muxing? 

Best regards,

Matthew Xu

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danielmartynek
NXP TechSupport
NXP TechSupport

Hello Matthew Xu,

Yes, that's what I mean.

The LPSPI module generates this PCS signal in Master mode, it cannot be disabled.

But if you don't need it in you application because the only Slave on the bus is always selected, then, you don't need to route the LPSPI_PCSn signal to a PORT.

BR, Daniel

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