FT232H datasheet(35/65 Pages) FTDI

35 / 65 page

Document No.: FT_000288

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

Datasheet Version 1.81

Clearance No.: FTDI #199

WRSTB#

RDSTB#

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).

Name

Description

Current pin state is read

RDSTB# is set inactive and data on the parallel I/O pins is read and sent to the

USB host.

RDSTB# is set active again, and any pins that are output will change to their

new data

1 clock cycle to allow for data setup

WRSTB# goes active. This indicates that the host PC has written new data to

the I/O parallel data pins

WRSTB# goes inactive

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

USB Rx

FIFO/

Buffer

Parallel I/O

data

Parallel

I/O pins

USB

WRSTB#

RDSTB#

USB Tx

FIFO/

Buffer

Figure 4.13 Bit-bang Mode Dataflow Illustration Diagram.

FT232H Datasheet(PDF) 35 Page - Future Technology Devices International Ltd.

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