UM232R USB-Serial UART Development Module Datasheet Version 1.02

© Future Technology Devices International Ltd. 2005

Page 8

3.3 Jumper Configuration Options

Table 2 - Jumper J1 Pin Description

Pin No. Name

Type Description

1

3V3

Output

3.3V output from integrated L.D.O. regulator. This pin is decoupled to ground on the module pcb with a 10nF

capacitor. The prime purpose of this pin is to provide the internal 3.3V supply to the USB transceiver cell and

the internal 1.5kΩ pull up resistor on USBDP. Up to 50mA can be drawn from this pin to power external logic if

required. This pin can also be used to supply the FT232RL’s VCCIO pin by connecting this pin to pin 4 (VIO),

or by connecting together pins 1 and 2 on jumper J1.

2

VIO

PWR

+1.8V to +5.25V supply to the UART Interface and CBUS I/O pins (1...3, 5, 6, 9...14, 22, 23). In USB bus

powered designs connect to 3V3 to drive out at 3.3V levels (connect jumper J1 pins 1 and 2 together), or

connect to VCC to drive out at 5V CMOS level (connect jumper J1 pins 2 and 3 together). This pin can also be

supplied with an external 1.8V - 2.8V supply in order to drive out at lower levels. It should be noted that in this

case this supply should originate from the same source as the supply to Vcc. This means that in bus powered

designs a regulator which is supplied by the 5V on the USB bus should be used.

3

VCC

PWR

VCC Output. This will be 5V from the USB bus if pins 1 and 2 on jumper J2 are connected. Alternativly, if the

module is in a self powered configuration, the supply to the VCC module pins (15 and 21) will be brought out

to this jumper pin.

Connect this jumper J1 pin 2 in order to supply the device IO pins from the supply to VCCIO.

Table 3 - Jumper J2 Pin Description

Pin No. Name

Type Description

1

USB

PWR

5V Power output USB port. For a low power USB bus powered design, up to 100mA can be sourced from the

5V supply on the USB bus. A maximum of 500mA can be sourced from the USB bus in a high power USB bus

powered design.

2

VCC

PWR

or

Output

Board supply input. Connect to jumper J2 pin 1 in order to supply the board from the USB bus.

This pin is internally connected to the VCC DIP pins. Remove the jumper connector in a self powered design.

3.4 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 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

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 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.

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