EVAL232R FT232RL USB to RS232 Evaluation Module Datasheet Version 0.90

© Future Technology Devices International Ltd. 2005

Page 8

3.3 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 MPROG, which can be downloaded from the FTDI website. The default

configuration is described in Section 8.

Table 4 - CBUS Signal Options

CBUS Signal Option Available On CBUS Pin...

Description

TXDEN

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

Enable transmit data for RS485

TXLED#

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

Transmit data LED drive - pulses low when transmitting data via

USB. See FT232R datasheet for more details.

RXLED#

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

Receive data LED drive - pulses low when receiving data via USB.

See FT232R datasheet for more details.

TX&RXLED#

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

LED drive - pulses low when transmitting or receiving data via

USB. See FT232R datasheet for more details.

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 P-

Channel logic level MOSFET switch. Enable the interface pull-down

option when using the PWREN# pin in this way.

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

24MHz Clock output.

CLK12

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

12MHz Clock output.

CLK6

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

6MHz 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.

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

3.4 RS232 Signal Descriptions

Table 5 - RS232 Signals

DB9 pin No. Name

Type

Description

1

DCD

Input

Data Carrier Detect control input

2

RXDATA

Input

Receive Asynchronous Data input.

3

TXDATA

Output

Transmit Asynchronous Data output.

4

DTR

Output

Data Terminal Ready control output / Handshake signal

5

GND

GND

Device groud supply pin.

6

DSR

Input

Data Set Ready control input / Handshake signal

7

RTS

Output

Request To Send Control Output / Handshake signal.

8

CTS

Input

Clear to Send Control input / Handshake signal.

9

RI

Input

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.