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How can I refresh KEA SPI data register for transmitting?

Question asked by Martin Zhang on Jun 12, 2019
Latest reply on Jun 14, 2019 by Kerry Zhou

Hi NXP Team,

We are developing a sensor just like KMA210, using S9KEAZN8AMFK as 24bit-SPI slave.

Time between SPI master CS low and CLK first rising clock is too short, about 4~5us. 

I find out it takes about 2us from CS falling edge to software capture the edge using FTM capture(and GPO output high level in FTM interrupt function). If I write one data to SPI0_D after CS low, it may not have enough time to transmit the writing data and send out wrong byte order.

So, I write one byte data to SPI0_D register before CS low. But it results in another problem, that is, I can not refresh the SPI0_D after writing it except completing one byte transmitting. If I have write one byte to SPI0_D, it would be out of date in several minutes later.


How can I refresh KEA SPI data register(SPI0_D) for transmitting?