UMFT234XD Datasheet, PDF (4/11 Pages) Future Technology Devices International Ltd. – UMFT234XD Breakout Modules

3.3 CBUS Signal Options
UMFT234XD Datasheet
Version 1.1
Document Reference No.: FT_000801 Clearance No.: FTDI# 327
CBUS Signal
Option
Available On
CBUS Pin
Description
Tristate
CBUS0
IO Pad is tri-stated
DRIVE_1
CBUS0
Output a constant 1
DRIVE_0
CBUS0
Output a constant 0
TXDEN
CBUS0
Enable transmit data for RS485
PWREN#
CBUS0
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.
TXLED#
CBUS0
Transmit data LED drive – open drain pulses low when transmitting data via
UART.
RXLED#
CBUS0
Receive data LED drive – open drain pulses low when receiving data via UART.
TX&RXLED#
CBUS0
LED drive – open drain pulses low when transmitting or receiving data via
UART.
SLEEP#
CBUS0
Goes low during USB suspend mode. Typically used to power down external
logic to RS232 level converter IC in USB to RS232 converter designs
CLK24MHz
CBUS0
24 MHz Clock output.**
CLK12MHz
CBUS0
12 MHz Clock output.**
CLK6MHz
CBUS0
6 MHz Clock output.**
GPIO
CBUS0
CBUS bit bang mode option. Allows up to 4 of the CBUS pins to be used as
general purpose I/O. A separate application note, AN232R-01, available from
FTDI website (www.ftdichip.com) describes in more detail how to use CBUS bit
bang mode.
BCD_Charger
CBUS0
Battery Charge Detect indicates when the device is connected to a dedicated
battery charger host. Active high output. NOTE: Requires a 10K pull-down to
remove power up toggling.
BCD_Charger#
CBUS0
Active low BCD Charger, driven by an open drain to ground with no internal
pull-up.
BitBang_WR#
CBUS0
Synchronous and asynchronous bit bang mode WR# strobe output.
BitBang_RD#
CBUS0
Synchronous and asynchronous bit bang mode RD# strobe output.
VBUS_Sense
CBUS0
Input to detect when VBUS is present.
Time_Stamp
CBUS0
Toggle signal which changes state each time a USB SOF is received
Keep_Awake#
CBUS0
Active Low input, prevents the chip from going into suspend.
Table 3.3 CBUS Configuration Control
* PWREN# must be used with a 10kΩ resistor pull up.
**When in USB suspend mode the outputs clocks are also suspended.
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