Copyright © 2016 Future Technology Devices International Limited

7

UMFT201XE Datasheet

Version 1.2

Doc ument Reference N o.: FT _000650 C learance N o.: FT DI#

292

4.3

CBUS Signals Options

The following options can be configured on the CBUS I/O pins. These options are all configured in the

internal MTP ROM using the utility software FT_PROG, which can be downloaded from the

CBUS Signal Option

Available On CBUS

Pin

Description

Tristate

CBUS0 - CBUS5

IO Pad is tri-stated

DRIVE_1

CBUS0 - CBUS5

Output a constant 1

DRIVE_0

CBUS0 - CBUS5

Output a constant 0

PWREN#

CBUS0-CBUS5

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.

NOTE: This function is driven by an open-drain to ground with no

internal pull-up; this is specially designed to aid battery charging

applications. UMFT231XE connects all CBUS and DBUS signals an

on-board 47K pull-up.

TXLED#

CBUS0 - CBUS5

Transmit data LED drive – pulses low when transmitting data via

USB.

RXLED#

CBUS0 - CBUS5

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

TX&RXLED#

CBUS0 - CBUS5

LED drive – pulses low when transmitting or receiving data via USB.

SLEEP#

CBUS0 - CBUS5

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.

CLK24MHz

CBUS0 - CBUS5

24 MHz Clock output.**

CLK12MHz

CBUS0 - CBUS5

12 MHz Clock output.**

CLK6MHz

CBUS0 - CBUS5

6 MHz Clock output.**

GPIO

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 MTP ROM. A separate

application note,

AN232R-01, available from FTDI website

(

www.ftdichip.com) describes in more detail how to use CBUS bit

bang mode.

BCD_Charger

CBUS0 - CBUS5

Battery charge Detect, indicates when the device is connected to a

dedicated battery charger host. Active high output.

BCD_Charger#

CBUS0 - CBUS5

Inverse of BCD Charger

BitBang_WR#

CBUS0 - CBUS5

Synchronous and asynchronous bit bang mode WR# strobe output.

BitBang_RD#

CBUS0 - CBUS5

Synchronous and asynchronous bit bang mode RD# strobe output.

I2C_TXE

CBUS0 - CBUS5

Transmit buffer empty, used to indicate to I2C master device status

of the FT201X transmit buffer

I2C_RXF

CBUS0 - CBUS5

Receive buffer full, used to indicate to I2C master device status of

FT201X receive buffer

VBUS_Sense

CBUS0 - CBUS5

Input to detect when VBUS is present.

Time_Stamp

CBUS0 - CBUS5

Toggle signal which changes state each time a USB SOF is received

Keep_Awake#

CBUS0 - CBUS5

Active Low input, prevents the chip from going into suspend.

Table 4.2 – CBUS Signal Options