Datasheet

© Copyright 2005-2011 Future Technology Devices International Ltd
10
Document Reference No.: FT_000051
UM232R USB - Serial UART Development Module
Datasheet Version 1.1
Clearance No.: FTDI# 125
4.4 CBUS Signal Options
The following options can be configured on the CBUS I/O pins. These options are all configured in the
internal EEPROM using the utility software FT_PROG, which can be downloaded from the www.ftdichip.com.
The default configuration is described in Section 9.
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
Goes low after the device is configured by USB, then high
during USB suspend. Can be used to control power to
external logic in high power designs. Needs 10k pull up to
VCC.
TXLED#
CBUS0, CBUS1, CBUS2, CBUS3,
CBUS4
Transmit data LED drive – pulses low when transmitting
data via USB.
RXLED#
CBUS0, CBUS1, CBUS2, CBUS3,
CBUS4
Receive data LED drive – pulses low when receiving data
via USB.
TX&RXLED#
CBUS0, CBUS1, CBUS2, CBUS3,
CBUS4
LED drive – pulses low when transmitting or receiving
data via USB. See
SLEEP#
CBUS0, CBUS1, CBUS2, CBUS3,
CBUS4
Goes low during USB suspend mode. Typically used to
power down an external TTL to RS232 level converter I.C.
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 will describe
in more detail how to use CBUS bit bang mode.
(www.ftdichip.com)
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 4.4 CBUS Signal Options