Datasheet

Copyright © 2009 Future Technology Devices International Limited 12
Document No.: FT_000053
FT232R USB UART IC Datasheet Version 2.02
Clearance No.: FTDI# 38
3.5 CBUS Signal Options
The following options can be configured on the CBUS I/O pins. CBUS signal options are common to both
package versions of the FT232R. These options can be configured in the internal EEPROM using the
software utility MPROG, which can be downloaded from the FTDI Utilities (www.ftdichip.com) . The
default configuration is described in Section 8.
CBUS
Signal
Option
Available On CBUS Pin Description
TXDEN CBUS0, CBUS1, CBUS2, CBUS3, CBUS4 Enable transmit data for RS485
PWREN# CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
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.*
TXLED# CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
Transmit data LED drive – pulses low when
transmitting data via USB. See Section 7.5 for more
details.
RXLED# CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
Receive data LED drive – pulses low when receiving
data via USB. See Section 7.5 for more details.
TX&RXLED# CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
LED drive – pulses low when transmitting or
receiving data via USB. See Section 7.5 for more
details.
SLEEP# CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
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.
CLK48 CBUS0, CBUS1, CBUS2, CBUS3, CBUS4 48MHz Clock output.**
CLK24 CBUS0, CBUS1, CBUS2, CBUS3, CBUS4 24 MHz Clock output.**
CLK12 CBUS0, CBUS1, CBUS2, CBUS3, CBUS4 12 MHz Clock output.**
CLK6 CBUS0, CBUS1, CBUS2, CBUS3, CBUS4 6 MHz Clock output.**
CBitBangI/O CBUS0, CBUS1, CBUS2, CBUS3
CBUS bit bang mode option. Allows up to 4 of the
CBUS pins to be used as general purpose I/O.
Configured individually for CBUS0, CBUS1, CBUS2
and CBUS3 in the internal EEPROM. A separate
application note, AN232R-01 , available from FTDI
website (www.ftdichip.com) describes in more detail
how to use CBUS bit bang mode.
BitBangWRn CBUS0, CBUS1, CBUS2, CBUS3
Synchronous and asynchronous bit bang mode WR#
strobe output.
BitBangRDn CBUS0, CBUS1, CBUS2, CBUS3
Synchronous and asynchronous bit bang mode RD#
strobe output.
Table 3.9 CBUS Configuration Control
* PWREN# should be used with a 10kΩ resistor pull up.
**When in USB suspend mode the outputs clocks are also suspended.