toim3232 ETC-unknow, toim3232 Datasheet - Page 6

• Manufacturer Part Number: toim3232
• Description: Infrared Irda Integrated Interface Circuits
• Manufacturer: ETC-unknow

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
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-
ing is deactivated. S1 is to be connected to V
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).
TOIM3000/3232
6 (9)
m
s and noise filtering.
Preliminary Information
CC
and S0 to
Control Byte (8 bit)
where
X:
S1, S2:
S0:
B0 .. B3:
*) not recommended
Baud Rate Select Words
Note: IrDA standard only supports 2.4, 9.6, 19.2, 57.6,
and 115.2 kbit/s.
<––––– First char. ––––> <––– Second char. ––––>
X
B3
0
0
0
0
0
0
0
0
1
1
1
1
1
S2
B2
0
0
0
0
1
1
1
1
0
0
0
0
1
S1
Don’t care
User-programmable bit
IrDA pulse select
= (1)
= (0)
Baud rate selects, B0 = LSB
B1
0
0
1
1
0
0
1
1
0
0
1
1
0
TELEFUNKEN Semiconductors
S0
B0
B3
0
1
0
1
0
1
0
1
0
1
0
1
0
1.627
3/16 bit time pulses *)
Second
B2
m
Char.
Rev. A4, 26-Mar-96
s output pulses
A
B
C
0
1
2
3
4
5
6
7
8
9
B1
115.2 k
57.6 k
38.4 k
19.2 k
14.4 k
Baud
12.8k
2.4 k
Rate
7.2 k
4.8 k
3.6 k
1.8 k
1.2 k
9.6k
B0