3

Bit Bang Modes for the FT232R and FT245R

Copyright © 2006 Future Technology Devices International Ltd.

1.2

Asynchronous Bit Bang Mode

Asynchronous Bit Bang mode is the same as BM-style Bit Bang mode. Any data written to the

device in the normal manner will be self-clocked onto the data pins which have been configured as

outputs. Each pin can be independently set as an input or an output. The rate that the data is

clocked out at is controlled by the Baud rate generator.

For the data to change there, has to be new data written and the Baud rate clock has to tick. If no

new data is written to the device, the pins will hold the last value written.

When Asynchronous Bit Bang mode is enabled the IO signal lines are configured as follows:

FT232RL/

FT245RL

Pin

Number

FT232RQ/

FT245RQ

Pin

Number

Signal

Type

Description

1

30

D0

Input/Output

Bit Bang Data Bus Bit 0

5

2

D1

Input/Output

Bit Bang Data Bus Bit 1

3

32

D2

Input/Output

Bit Bang Data Bus Bit 2

11

8

D3

Input/Output

Bit Bang Data Bus Bit 3

2

31

D4

Input/Output

Bit Bang Data Bus Bit 4

9

6

D5

Input/Output

Bit Bang Data Bus Bit 5

10

7

D6

Input/Output

Bit Bang Data Bus Bit 6

6

3

D7

Input/Output

Bit Bang Data Bus Bit 7

In the case of the FT232R, any of CBUS0, CBUS1, CBUS2 or CBUS3 can be configured to bring

out the internal RD# or WR# strobes when the device is in Asynchronous Bit Bang mode, this is

the same as the Enhanced Asynchronous Bit Bang mode of the FT2232 device. Alternatively, the

CBUS pins can be used to provide clock signals by setting the appropriate values in the EEPROM.

The CBUS must be configured in the FT232R EEPROM. This option is not available for the

FT245R.

FT232RL

Pin

Number

FT232RQ

Pin

Number

Signal

Type

Description

23

22

C0

Input/Output

Configurable function

22

21

C1

Input/Output

Configurable function

13

10

C2

Input/Output

Configurable function

14

11

C3

Input/Output

Configurable function

A number of D2XX driver commands are needed to use Asynchronous Bit Bang mode. The

commands of interest are listed below: