TOIM3000/3232

TELEFUNKEN Semiconductors

Rev. A4, 26-Mar-96

Preliminary Information

6 (9)

Operation Description

Features only for TOIM3000

The TOIM3000 uses 2 clocks from the UART: the

1.8432 MHz clock and the Baud_out clock for its internal

timing. Both are connected to XIN and B_CLK, respec-

tively. The B_CLK is used as a reference for pulse

stretching whereas XIN is used as a time base for pulse

shortening to 1.627

ms and noise filtering.

Single clock operation

TOIM3000 can be operated with only a single clock. In

this case, the 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-

GND.

We strongly recommend not to use this mode in

battery-operated systems because the 3/16 pulse

length at lower bit rates consumes more power than

the shorter pulses. At a baud rate of 9600 bit/s, the ra-

tio of power consumption of both modes is a factor of

12 (!).

The TOIM3000 interfaces to an RS232 level converter

through two pins, RD_232 and TD_232. These two pins

provide the extra function that a single TOIM3000 IC can

time share with both an infrared IrDA port and an RS232

port. Whenever RESET = 0, the TOIM3000 links to the

infrared transceiver TFDS3000 through RD_IR and

TD_IR pins. On the other hand, when RESET = 1, the

TOIM3000 links to the RS232 port through RD_232 and

TD_232 pins (see figure 1).

Features only for TOIM3232

The baud rate at which an RS232 serial port communi-

cates with the external adapter is programmable inside

the TOIM3232. This programmable baud rate should be

used when the baud clock and the UART oscillator clock

are not available. When BR/D = 0, the TOIM3232 inter-

prets the signals at RD_232 and RD_IR pins as data to be

transmitted and received data. On the other hand, when-

ever BR/D = 1, the TOIM3232 interprets the seven LSBs

at the RD_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”) (see figure 2).

Control Byte (8 bit)

<––––– First char. ––––>

<––– Second char. ––––>

X

S2

S1

S0

B3

B2

B1

B0

where

X:

Don’t care

S1, S2:

User-programmable bit

S0:

IrDA pulse select

= (1)

1.627

ms output pulses

= (0)

3/16 bit time pulses *)

B0 .. B3:

Baud rate selects, B0 = LSB

*) not recommended

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

Second

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

12.8k

0

1

1

0

6

9.6k

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