FT232H datasheet(30/65 Pages) FTDI

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Document No.: FT_000288

FT232H SINGLE CHANNEL HI-SPEED USB TO MULTIPURPOSE UART/FIFO IC

Datasheet Version 1.81

Clearance No.: FTDI #199

4.6 FT1248 Interface Mode Description

The FT232H supports a half duplex FT1248 Interface that provides a flexible data communication and

high performance interface between the FT232H as a FT1248 slave and an external FT1248 master. The

FT1248 protocol is a dynamic bi-directional data bus interface that can be configured as 1, 2, 4, or 8-bits

wide.

[7:0]

SCLK

MIOSIO

MISO

SS#

SCLK

MIOSIO

MISO

SS#

FPGA (FT1248 Master)

FT232H (FT1248 Slave)

Figure 4.7 FT1248 Bus with Single Master and Slave.

In the FT1248 there are 3 distinct phases:

While SS_n is inactive, the FT1248 reflects the status of the write buffer and read buffers on the

MIOSIO[0] and MISO wires respectively. Additionally, the FT1248 slave block supports multiple slave

devices where a master can communicate with multiple FT1248 slave devices. When the slave is sharing

buses with other FT1248 slave devices, the write and read buffer status cannot be reflected on the

MIOSIO[0] and MISO wires during SS_n inactivity as this would cause bus contention. Therefore, it is

possible for the user to select whether they wish to have the buffer status switched on or off during

inactivity. When SS_n is active a command/bus size phase occurs first. Following the command phase is

the data phase, for each data byte transferred the FT1248 slave drives an ACK/NAK status onto the MISO

wire. The master can send multiple data bytes so long as SS_n is active, if a unsuccessful data transfer

occurs, i.e. a NAK happens on the MISO wire then the master should immediately abort the transfer by

de-asserting SS_n.

BUS TURNAROUND

WRITE DATA

TXE#

CMD

CLK

SCLK

SS_n

MIOSIO[0]

RXF#

MISO

RXF#

RDATA0

RDATA1

RDATA2

TXE#

CMD

WDATA 0

WDATA 1

TXE#

WRITE

READ

RXF#

STATUS

Figure 4.8: FT1248 Basic Waveform Protocol.

Section 4.6.2 illustrates the FT1248 write and read protocol operating in 1-bit mode. For details regarding

2-bit, 4-bit and 8-bit modes, please refer to application note AN_167_FT1248 Parallel Serial Interface

Basics available at http://www.ftdichip.com.

FT232H Datasheet(PDF) 30 Page - Future Technology Devices International Ltd.

FT232H Datasheet(HTML) 30 Page - Future Technology Devices International Ltd.

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