LSI Logic Confidential
15-10
Serial I/O Port
Copyright © 2001, 2002 by LSI Logic Corporation. All rights reserved.
15.2.2 SPI Interface: Protocol Description
DoMiNo always acts as a master in SPI transfers.
and
the format of a typical 32-bit SPI data transfer, and the timing
relationships between successive bytes transferred. The circled numbers
in
and
refer to the steps that follow.
Figure 15.5 32-Bit SPI Data Transfer Format
Figure 15.6 Inter-Byte Timing Relationship
1.
SIO_SPI_CS asserts: Chip select signal asserts in preparation for
data transfer. The CSDL field in the SPI_CONFIG register allows
adjustment of the setup and hold times of the SIO_SPI_CS[n] signals
about SIO_SPI_CLK. CSDL is the number of half SIO_SPI_CLK
cycles between SIO_SPI_CS assertion and SIO_SPI_CLK ungating.
2.
First Bit of Data Transfer: Data simultaneously gets shifted out the
SIO_SPI_MOSI pin and shifted in the SIO_SPI_MISO pin.
Depending on the LSBF setting in the SPI_CONFIG register, this
SIO_SPI_CLK (O)
SIO_SPI_CS (O)
SIO_SPI_CS (O)
SIO_SPI_CS (I)
din[31]
din[30]
din[29]
din[1]
din[0]
din[31]
din[30]
din[29]
din[1]
din[0]
1
2
5
4
IO_SPI_CLK (O)
csbk
5
IO_SPI_CS(O)
1
3