VNC2 参数 Datasheet PDF下载

Document No.: FT_000138

VINCULUM-II EMBEDDED DUAL USB HOST CONTROLLER IC Datasheet

Version -

1.0

Clearance No.: FTDI#

143

6.3.3 Half Duplex, 4 pin

In half duplex mode, the MOSI signal is shared for both Master to Slave and Slave to Master

communications. When using 4 pins, the MISO signal carries the status bits. The Master initiates data

write transfer, this by asserting SS# and then sending out a command byte. This has the same format as

that shown in

The Slave sends status during this command phase and if this indicates that

the Slave can accept data the Master will follow this up with a byte of write data. If the status continues

to indicate that more data can be written, a whole stream of data can be written following one single

command. The operation completes when the Master raises SS# again.

is an example of this.

SS#

MOSI

8 bit CMD

W0

W1

W2

MISO

STATUS

STATUS

STATUS

STATUS

Figure 6-8 Half Duplex Data Master Write

Data reads are similar, apart from the MOSI pin changing from Slave input to Slave output after the

command phase.

is an example. In this diagram, the Master drives the command while the

Slave returns with status. Then the MOSI buffers are turned round and a stream of read data is sent from

the Slave to the Master on the MOSI signal.

Master to Slave

SS#

Slave to Master

MOSI

8 bit CMD

R0

R1

R2

MISO

STATUS

STATUS

STATUS

STATUS

Figure 6-9 Half Duplex Data Master Read

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