VNC2-32Q1B 参数 Datasheet PDF下载

Document No.: FT_000138

VINCULUM-II EMBEDDED DUAL USB HOST CONTROLLER IC Datasheet

Version -

1.2

Clearance No.: FTDI#

143

6.2 Serial Peripheral Interface – SPI Modes

The Serial Peripheral Interface Bus is an industry standard communications interface. Devices

communicate in Master / Slave mode, with the Master initiating the data transfer.

VNC2 has one master module and two slave modules. Each SPI slave module has four signals – clock,

slave select, MOSI (master out – slave in) and MISO (master in – slave out). The SPI Master has the

same four signals as the slave modules but with one additional signal because it requires a slave select

for the second slave module.

lists how the signals are named in each module.

The SPI Master clock can operate up to one half of the CPU system clock depending on what power mode

the device is set to:

Normal power mode 48Mhz would set the SPI maximum clock to 24Mhz

Low power mode 24Mhz would set the SPI maximum clock to 12Mhz

Lowest power mode 12Mhz would set the SPI maximum clock to 6hMz

Module

Signal Name

spi_s0_clk

SPI Slave

0

spi_s0_ss#

spi_s0_mosi

spi_s0_miso

spi_s1_clk

SPI Slave

1

spi_s1_ss#

spi_s1_mosi

spi_s1_miso

spi_m_clk

SPI

Master

spi_m_mosi

spi_m_miso

spi_m_ss_0#

spi_m_ss_1#

Table 14 SPI Signal Names

Type

Input

Input

Input

Output

Input

Input

Input

Output

Output

Output

Input

Output

Output

Description

Clock input – slave 0

Active low chip select input – slave 0

Master out serial in – slave 0

Master in slave out – slave 0

Clock input – slave 1

Active low chip select input – slave 1

Master out slave in – slave 1

Master in slave out – slave 1

Clock output – master

Master out slave in - master

Master in slave out - master

Active low slave select 0 from master to slave 0

Active low slave select 1 from master to slave 1

The SPI slave protocol by default does not support any form of handshaking. FTDI have added extra

modes to support handshaking, faster throughput of data and reduced pin count. There are 5 modes

(Table 15) of operation in the VNC2 SPI Slave.

Full Duplex –

Section 6.3.2

Half Duplex, 4 pin -

Section 6.3.3

Half Duplex, 3 pin -

Section 6.3.4

Unmanaged -

Section 6.3.5

VNC1L legacy mode –

Section 6.3.6

Mode

VNC1L

Full Duplex

Half Duplex 4

pin

Half Duplex 3

pin

Unmanaged

Pins

4

4

4

3

4

Word Size

12

8

8

8

8

Handshaking

Yes

Yes

Yes

Yes

No

Speed

Read 66%

Write 66%

Read 50%

Write 100%

Read 100%

Write 100%

Read 50%

Write 50%

Read 100%

Write 100%

Comments

Legacy mode

MOSI becomes

bi-directional

MOSI becomes

bi-directional

Table 15 - SPI Slave Speeds

VNC2 SPI Master is described in

Section 6.4.1 SPI Master Signal Descriptions.

shows the SPI master signals and the available pins that they can be mapped to depending on

the package size. Further details on the configuration of input and output signals are available in

Section

5 -

.

Copyright © 2010 Future Technology Devices International Limited

41