3.3 CBUS Signal Options
Page 8
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 MPROG, which can be downloaded from the
The default
configuration is described in Section 8.
Table 4 - CBUS Signal Options
CBUS Signal Option Available On CBUS Pin...
TXDEN
TXLED#
RXLED#
TX&RXLED#
PWREN#
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
Description
Enable transmit data for RS485
Transmit data LED drive - pulses low when transmitting data via
USB. See FT232R datasheet for more details.
Receive data LED drive - pulses low when receiving data via USB.
See FT232R datasheet for more details.
LED drive - pulses low when transmitting or receiving data via
USB. See FT232R datasheet for more details.
Goes low after the device is configured by USB, then high during
USB suspend. 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# pin in this way.
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.
48MHz Clock output.
24MHz Clock output.
12MHz Clock output.
6MHz Clock output.
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.
Synchronous and asynchronous bit bang mode WR# strobe Output
Synchronous and asynchronous bit bang mode RD# strobe Output
SLEEP#
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CLK48
CLK24
CLK12
CLK6
CBitBangI/O
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3, CBUS4
CBUS0, CBUS1, CBUS2, CBUS3
BitBangWRn
BitBangRDn
CBUS0, CBUS1, CBUS2, CBUS3
CBUS0, CBUS1, CBUS2, CBUS3
3.4 RS232 Signal Descriptions
Table 5 - RS232 Signals
DB9 pin No. Name
1
2
3
4
5
6
7
8
9
DCD
RXDATA
TXDATA
DTR
GND
DSR
RTS
CTS
RI
Type
Input
Input
Output
Output
GND
Input
Output
Input
Input
Description
Data Carrier Detect control input
Receive Asynchronous Data input.
Transmit Asynchronous Data output.
Data Terminal Ready control output / Handshake signal
Device groud supply pin.
Data Set Ready control input / Handshake signal
Request To Send Control Output / Handshake signal.
Clear to Send Control input / Handshake signal.
Ring Indicator control input. When remote wakeup is enabled in the FT232RL’s internal
EEPROM taking RI# low can be used to resume the PC USB host controller from suspend.
EVAL232R FT232RL USB to RS232 Evaluation Module Datasheet Version 0.90
© Future Technology Devices International Ltd. 2005
FTDI [ FUTURE TECHNOLOGY DEVICES INTERNATIONAL LTD. ]
