IOBUS1 datasheet(41/88 Pages) FTDI

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Datasheet

Vinculum-II Embedded Dual USB Host Controller IC

V ers ion 1 .7

Doc ument N o.: FT _000138 C learance N o.: FT DI# 1 43

Figure 6.3 - SPI CPOL CPHA Function

6.3 Serial Peripheral Interface – Slave

External - SPI Master

VNC2 - SPI Slave

CLK

SS#

MISO

MOSI

Figure 6.4 SPI Slave block diagram

VNC2 has two SPI Slave modules both of which use four wire interfaces: MOSI, MISO, CLK and SS#.

Their main purpose is to send data from main memory to the attached SPI master, and / or receive data

and send it to main memory. The SPI Slave is controlled by the internal CPU using internal memory

mapped I/O registers. It operates from the main system clock, although sampling of input data and

transmission of output data is controlled by the SPI clock (CLK). An SPI transfer can only be initiated by

the SPI Master and begins with the slave select signal being asserted. This is followed by a data byte

being clocked out with the master supplying CLK. The master always supplies the first byte, which is

called a command byte. After this the desired numbe r of data bytes are transferred before the

transaction is terminated by the master de -asserting slave select. An SPI Master is able to abort a

transfer at any time by de-asserting its SS# output. This will cause the Slave to end its current transfer

and return to idle state.

IOBUS1 データシート(PDF) 41 Page - Future Technology Devices International Ltd.