Document No.: FT_000061
FT2232H DUAL HIGH SPEED USB TO MULTIPURPOSE UART/FIFO IC
Datasheet Version 2.09
Clearance No.: FTDI#77
4.7 MCU Host Bus Emulation Mode
MCU host bus emulation mode uses both of the FT2232H‟s A and B channel interfaces to make the chip
emulate a standard 8048/8051 MCU host bus. This allows peripheral devices for these MCU families to be
directly connected to USB via the FT2232H.
The lower 8 bits (AD7 to AD0) is a multiplexed Address / Data bus. A15 to A18 provide upper (extended)
addresses. There are 4 basic operations:-
1) Read (does not change A15 to A8)
2) Read Extended (changes A15 to A8)
3) Write (does not change A15 to A8)
4) Write Extended (changes A15 to A8)
MCU Host Bus Emulation mode is enabled using Set Bit Bang Mode driver command. A hex value of 8 will
enable it, and a hex value of 0 will reset the device. The FT2232H operates in the same way as the
FT2232D. See application note AN2232-02, “Bit Mode Functions for the FT2232D” for more details
and examples.
The MCU Host Bus Emulation Mode command set is fully described in application note AN_108 –
“Command Processor For MPSSE and MCU Host Bus Emulation Modes”.
When MCU Host Bus Emulation mode is enabled the IO signal lines on both channels work together and
the pins are configured as described in Table 3.11. The following sections give some details of the read
and write cycle waveforms and timings. The CLKOUT output clock can operate up to 60MHz.
In Host Bus Emulation mode the clock divisor has no effect. The clock divisor is used for serial data and is
a different part of the MPSSE block. In host bus emulation the 60MHz clock is always output and doesn‟t
change with any commands.
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