Document Number: 002-14826 Rev. *G
Page 19 of 65
PRELIMINARY
CYW43903
5.7 SPI
CYW43903 contains one SPI block. This block support a fixed SPI mode (CPOL = 0, CPHA = 0) and 8-bit data read/write.
■
CPOL = 0: Clock idles at 0, and each cycle consists of a pulse of 1. The leading edge is a rising edge, and the trailing edge is a
falling edge.
■
CPHA = 0: The "out" side changes the data on the trailing edge of the preceding clock cycle, while the "in" side captures the
data on (or shortly after) the leading edge of the clock cycle.
The SPI hardware block supports a hold time of 25ns and a maximum clock frequency of 40MHz. If a SPI slave does not support the
above mode or requires a hold time greater than 25ns, a bit banging software SPI driver should be used. Cypress's WICED SDK
provides and example of such a driver.
Note that the maximum SPI frequency support by a software SPI driver is much lower than 40 MHz.
SPI0 mentioned in
is multiplexed with GPIOs and can therefore support a bit banging based software SPI driver.