FT232R USB UART I.C. Datasheet Version 1.04

© Future Technology Devices International Ltd. 2005

Page 11

4.5 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 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 10.

Table 3 - CBUS Signal Options

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 P-

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

option when using the PWREN# pin in this way.

TXLED#

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

Transmit data LED drive - pulses low when transmitting data via

USB. See Section 9 for more details.

RXLED#

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

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

See Section 9 for more details.

TX&RXLED#

CBUS0, CBUS1, CBUS2, CBUS3, CBUS4

LED drive - pulses low when transmitting or receiving data via

USB. See Section 9 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 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