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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

5 I/O Multiplexer

FTDI devices typically have multiple interfaces available to communicate with external devices. VNC2 has

UART, SPI slave0, SPI slave1, SPI master, FIFO, GPIO, and PWM peripherals. The available packages for

VNC2 provide any of these interfaces to be active on the available pins through the use of an I/O

Multiplexer. Table 5.1 lists the signals available for each peripheral. Table 5.2 to 12 explain the use of

the I/O multiplexer.

Multiplexers are used to connect the VNC2 peripherals to the external IOBUS pins. This enables the

designer to select which IOBUS pins he wishes to map a particular peripheral to. Peripheral signals are

allocated to one of four groups, which connect to the I/O multiplexer. Each I/O peripheral signal can

connect to one out of every four external IOBUS pins. The IOBUS pin that a peripheral signal can connect

to is dictated by the peripheral signal’s group. For example, if a peripheral signal is allocated to group 0

then it can connect to IOBUS0, IOBUS4, IOBUS8, and IOBUS12 and so on. If a peripheral signal is

allocated to group 1 then it can connect to IOBUS1, IOBUS5, IOBUS9, and IOBUS13 and so on. Figure

5.1 details the I/O multiplexer concept, where, for example, a white peripheral signal can connect to any

white IOBUS pin; a green peripheral signal can connect to a green IOBUS pin. Figure 5.2, Figure 5.3 and

Figure 5.4 give examples of connecting peripheral signals to differing IOBUS pins.

The IO Multiplexer also provides the following features:



Ability to configure an I/O pad as an input, output or bidirectional pad.



At power on reset, all pins are set as inputs by default. Whenever the I/O Mux is enabled the pins

are configured as their default values listed Table 6 within section 3.12.

Note: It is recommended not to reassign the debug interface signal (debug_if) from its default

setting of IOBUS0 (Pin 11 on all packages). This assumes that the debug pin is required in the

application design, if not; pin 11 can be assigned to any other group 0 signal.

An application (IOMUX) within the RTOS is available to aid with pin configuration, Section 5.2 has more

details.

Further details of the IO Multiplexer are available within Application Note AN_139 Vinculum-II IO Mux

Explained.

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