IOBUS0 datasheet(43/88 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

6.3.2 Full Duplex

In full duplex mode, the SPI slave sends data on MISO line at the same time as it receives data on MOSI.

During the command phase this data is always the slave status byte. For a write command, write data

can be streamed out of MOSI and status can be sent during each write phase from slave to master. As

long as the slave status indicates that it can receive more data, the master can continue to stream

further write bytes. Figure 6.5 is an example of this.

SS#

MISO

MOSI

8 bit CMD

STATUS

Figure 6.5 Full Duplex Data Master Write

When the master is performing a data read, the data and status both need to share the same pin (MISO).

In this case the master and slave will exchange command and status bytes, followe d by the slave sending

its data. If the Master keeps SS# active the Slave will send a further status byte after the data followed

by another data byte. This continues until the Master indicates the end of the communications by raising

SS#. Figure 6.6 is an example of this.

SS#

MISO

MOSI

8 bit CMD

STATUS

Figure 6.6 Full Duplex Data Master Read

IOBUS0 数据表(PDF) 43 Page - Future Technology Devices International Ltd.