ft232hq Future Technology Devices International Ltd., ft232hq Datasheet - Page 37

• Manufacturer Part Number: ft232hq
• Description: Ft232h Single Channel Hi- Speed Usb To Multipurpose Uart/fifo Ic
• Manufacturer: Future Technology Devices International Ltd.

Figure 4.12 Synchronous Bit-Bang Mode Timing Interface Example
WRSTB# = this output indicates when new data has been written to the I/O pins from the Host PC (via
the USB interface).
Table 4.3 Synchronous Bit-Bang Mode Timing Interface Example Timings
RDSTB# = this output rising edge indicates when data has been read from the I/O pins and sent to the
Host PC (via the USB interface).
The WRSTB# goes active in t5. The WRSTB# goes active when data is read from the USB RXFIFO (i.e.
sent from the PC). The RDSTB# goes inactive when data is sampled from the pins and written to the USB
TXFIFO (i.e. sent to the PC). The SETUP command to the FT232H is used to setup the bit-mode. This
command also contains a byte wide data mask to set the direction of each bit. The direction on each pin
doesn‟t change unless a new SETUP command is used to modify the direction.
The WRSTB# and RDSTB# strobes are only a guide to what may be happening depending on the
direction of the bus. For example if all pins are configured as inputs, it is still necessary to write to these
pins in order to get the FT232H to read those pins even though the data written will never appear on the
pins.
Signals and data-flow are illustrated in Figure 4.13
Figure 4.13 Bit-bang Mode Dataflow Illustration Diagram.
USB
WRSTB#
RDSTB#
Name
t1
t2
t3
t4
t5
t6
USB Rx
USB Tx
Buffer
FIFO/
Buffer
FIFO/
Copyright © 2011 Future Technology Devices International Limited
RDSTB# is set inactive and data on the parallel I/O pins is read and sent to the
WRSTB# goes active. This indicates that the host PC has written new data to
RDSTB# is set active again, and any pins that are output will change to their
FT232H SINGLE CHANNEL HI-SPEED USB TO MULTIPURPOSE UART/FIFO IC
1 clock cycle to allow for data setup
Parallel I/O
WRSTB#
the I/O parallel data pins
Current pin state is read
RDSTB#
data
WRSTB# goes inactive
Description
USB host.
new data
I/O pins
Parallel
Document No.: FT_000288
Clearance No.: FTDI #199
Datasheet Version 1.0
37