FT234XD-R Datasheet, PDF (9/37 Pages) Future Technology Devices International Ltd. – USB to BASIC UART IC

3.2 CBUS Signal Options
FT234XD USB TO BASIC UART IC
Version 1.2
Document No.: FT_000753 Clearance No.: FTDI#324
The following options can be configured on the CBUS0 I/O pin. These options can be configured in the
internal MTP memory using the software utility FT_PROG which can be downloaded from the FTDI Utilities
(www.ftdichip.com). The default configuration is described in Section 8.
CBUS Signal
Option
CBUS Pin
Description
TRI-STATE
DRIVE 1
DRIVE 0
TXDEN
PWREN#
TXLED#
RXLED#
TX&RXLED#
SLEEP#
CLK24MHz
CLK12MHz
CLK6MHz
GPIO
BCD Charger
BCD Charger#
BitBang_WR#
BitBang_RD#
VBUS Sense
Time Stamp
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
CBUS0
IO Pad is tri-stated
Output a constant 1
Output a constant 0
Enable transmit data for RS485
Output is low after the device has been configured by
USB, then high during USB suspend mode. This output
can be used to control power to external logic P-Channel
logic level MOSFET switch. Enable the interface pull-down
option when using the PWREN# in this way.
Transmit data LED drive – pulses low when transmitting
data via USB. See Section 7.5 for more details.
Receive data LED drive – pulses low when receiving data
via USB. See Section 7.5 for more details.
LED drive – pulses low when transmitting or receiving
data via USB. See Section 7.5 for more details.
Goes low during USB suspend mode. Typically used to
power down an external TTL to RS232 level converter IC
in USB to RS232 converter designs.
24 MHz Clock output.*
12 MHz Clock output.*
6 MHz Clock output.*
CBUS bit bang mode option. Allows the CBUS pin to be
used as general purpose I/O. Configured in the internal
MTP memory. A separate application note, AN232R-01,
available from FTDI website (www.ftdichip.com) describes
in more detail how to use CBUS bit bang mode.
Battery Charging Detection indicates when the device is
connected to a dedicated battery charger host. Active
high output.
Inverse of BCD Charger
Synchronous and asynchronous bit bang mode WR#
strobe output.
Synchronous and asynchronous bit bang mode RD#
strobe output.
Input to detect when VBUS is present.
Toggle signal which changes state each time a USB
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