TOIM3232

Vishay Telefunken

Not for new designs

Rev. A1.1, 02-Apr-01

3 (9)

www.vishay.com

Document Number 82521

Operation Description

Figure KEIN MERKER shows a typical example of an

RS232 port interface. The TOIM3232 connects to an

RS232 level converter on one side, and an infrared

transceiver on the other. Software can be written to

program the TOIM3232 baud rate generator. When

BR/D = 0, the TOIM3232 interprets TD_232 data as

data transmitted to the TFDS4000. On the other hand,

whenever BR/D = 1, the TOIM3232

interprets

TD_232 as Control Word. Baud rate can be

programmed to operate from 1200 bit/s to 115 kbit/s.

As RS232 level converter, EIA232 or MAX232 or

equivalent are recommended.

Typical external resistors and capacitors are needed

as shown in the TFDx4xxx references.

The output pulse length can be programmed, see

chapter “Operation Description”. To use 1.627

ms

output pulses is strongly recommended to save

battery power. A resonator like a Matura Ceramic

recommended.

We strongly recommend not to use this 3/16 mode

because 3/16 pulse length at lower bit rates

consumes more power than the shorter pulse. At

a data rate of 9600 bit/s, the ratio of power

consumption of both modes is a factor of 12 (!).

Features of TOIM3232

The baud rate at which an RS232 serial port

communicates

with

the

external

adapter

is

programmable

inside

the

TOIM3232.

This

programmable baud rate is especially useful when the

baud clock and the UART oscillator clock are not

available and must be regenerated. When BR/D = 0,

the TOIM3232 interprets the signals at TD_232 as

transmit and RD_IR as received data. On the other

hand, whenever BR/D = 1, the TOIM3232 interprets

the 7 LSBs at the TD_232 input as the Control Word.

The operating baud rate will change to its supposedly

new baud rate when the BR/D returns back to

LOW (“0”) Set the UART to 8 bit, no parity, 1 stop bit.

Control Byte (8 bit)

First Character

Second character

X

S2

S1

S0

B3

B2

B1

B0

LSB

where

X:

Do not care

S1, S2:

User programmable bit to program the

outputs S1 and S2

S0:

IrDA pulse select

= (1)

1.627

ms output pulses

= (0)

3/16 bit time pulses,

not recommended

B0 .. B3:

Baud rate select words

Baud Rate Select Words

Note:

IrDA standard only supports 2.4, 9.6, 19.2, 57.6, and

115.2 kbit/s.

B3

B2

B1

B0

2nd

Char

Baud

Rate

0

0

0

0

0

115.2 k

0

0

0

1

1

57.6 k

0

0

1

0

2

38.4 k

0

0

1

1

3

19.2 k

0

1

0

0

4

14.4 k

0

1

0

1

5

12.8 k

0

1

1

0

6

9.6 k

0

1

1

1

7

7.2 k

1

0

0

0

8

4.8 k

1

0

0

1

9

3.6 k

1

0

1

0

A

2.4 k

1

0

1

1

B

1.8 k

1

1

0

0

C

1.2 k