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WKowo
Associate II
Jul 29, 2019 3:55 AM UTC
Solved

Recognizing SPI data reception in STM32F429

I'd like to ask how the STM32F429 recognizes data reception in case of SPI while there is no any start bit? I know that there is RXNE bit in SPI_SR status register, but how SPI knows where is the first bit of the transmitted byte? Is it somehow synchronized with SPI data transmission? I mean the first transmitted bit is some kind of trigger for recognizing first received bit (using of course CLK)?

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waclawek.jan
waclawek.janBest answer
Super User
Jul 29, 2019 4:42 AM UTC

If set as master, then it's in the control of clock (SCK). The first bit corresponds to the first transmitted clock.

If set as slave, then it's the first clock after NSS transitions from high to low.

JW

2 replies

waclawek.jan
waclawek.janBest answer
Super User
Jul 29, 2019 4:42 AM UTC

If set as master, then it's in the control of clock (SCK). The first bit corresponds to the first transmitted clock.

If set as slave, then it's the first clock after NSS transitions from high to low.

JW

WKowo
WKowoAuthor
Associate II
Jul 29, 2019 5:17 AM UTC

Thank you for your answer.