TOIM3000/3232

TELEFUNKEN Semiconductors

Rev. A4, 26-Mar-96

Preliminary Information

4 (9)

Application

OUT1

UART

TFDS

3000

RS232

SOUT

SIN

XOUT

BAUDOUT

RESET

TD_UART

RD_UART

XIN

B_CLK

TD_IR

RD_IR

TD_232

RD_232

TXD

RXD

TXD

RXD

SD

TOIM3000

V

R1

R2

C1, C2

83

S0 S1

CC

V

CC

Figure 1. TOIM3000 – UART interface

(built-in infrared port)

RS232

9–pin

connector

TOIM3232

TFDS3000

TXD

RXD

VCC

TD_IR

RD_IR

RESET

BR/D

TD_UART

RD_UART

3.6842 MHz

X1

X2

pin 7, RTS

Level

converter

VCC_SD

pin 3, TXD

pin 2, RXD

pin 4, DTR

Figure 2. TOIM3232 – RS232 port interface

(external infrared adapter)

Figure 1 shows a typical example of a UART interface.

As shown, XIN accepts the 1.8432 MHz input clock, and

B_CLK accepts the 16 times baud rate clock.

Set S1 = S0 = LOW (“0”). When RESET = 0, the

TOIM3000 sends the data to, or receives the data from the

infrared transceiver TFDS3000. If Reset is active,

RESET = 1, the TOIM3000 handles the normal electrical

data exchange with the RS232 port.

R1 = 2.2 k

W optional (only necessary when RxD–RD IR

line is capacitive loaded).

R2 = 100

W, R3 = 10 W, C1 = 6.8 mF and C2 = 0.1 mF. C1

value of R3 should be reduced, see introductory text).

Single clock operation

TOIM3000 can be operated with only a single clock. In

this case, B_CLK and XIN are tight together and con-

nected to the Baudout pin of the UART. The pulse width

is then shortened to 3/16 of the bit length and noise filter-

to GND.

Figure 2 shows a typical example of an RS232 port inter-

face. The TOIM3232 interfaces the RS232 port to an

infrared transceiver. Due to the various voltage levels, an

additional level converter (discrete or integrated) is nec-

sessary. The baud rate generator is programmable. A

description of programming is given in the Chapter “Soft-

ware for the TOIM3232” page 7 (IrDA Design Guide).

When BR/D = 0, the TOIM3232 interprets RD_232 data

as data transmitted to the TFDS3000. On the other hand,

whenever BR/D = 1, the TOIM3232 interprets RD_232

as the control word. The baud rate can be programmed to

operate from 1200 bit/s to 115 kbit/s. As RS232 level

converter, EIA232 or MAX232 or equivalent should be

used.

The external resistors and capacitors needed are shown in

figure 1. Please also refer to figure 1 for the recom-

mended power supply filter and pull-up resistors.

The output pulse length can be programmed, see chapter

“Operation Description”. It is strongly recommended to

use 1.627

ms output pulses to save battery power.