Data Transfer

Zynq UltraScale+ Device Technical Reference Manual (UG1085)

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2.4 English

The SCLK clock and MOSI signals are under control of the master. Data to be transmitted is written into the TXFIFO by software using register writes and then unloaded for transmission by the controller hardware in a manual or automatic start sequence. Data is driven onto the master output (MOSI) data pin. Transmission is continuous while there is data in the TXFIFO. Data is received serially on the MISO data pin and is loaded eight bits at a time into the RXFIFO. Software reads the RXFIFO using register reads. For every n bytes written to the TXFIFO, there are n bytes stored in RXFIFO that must be read by software before starting the next transfer.