IC-TW3 Datasheet, PDF (12/24 Pages) IC-Haus GmbH – SENSOR SIGNAL CONDITIONER WITH TEMPERATURE COMPENSATION AND LINE DRIVER

iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
1-WIRE INTERFACE
Rev B1, Page 12/24
The 1-wire interface provides read and write access to
the register bank and to the external EEPROM. When
read access is not required an infrared phototransistor
can be directly connected to the pin in order to build
a cost effective wireless write-only port for in-field or
production programming.
The communication bit stream is pulse-width modu-
lated (PWM) as shown in Figure 1. A zero-bit is en-
coded as a short high followed by a long low. A one-bit
is encoded as a long high followed by a short low.
The modulated signal is independent of the receiver or
the transmitted clock frequency. Since iC-TW3 uses
a free-running oscillator it is important to implement a
robust, frequency insensitive protocol.
1- wire timing
idle start
1
0
delay
idle
Parameter
t_start
t_long
t_short
t_delay
t_idle
t
long
t
long
t
short
t
short
t
long
t
t
t
short
delay
idle
Figure 1: Pulse width modulation bit stream
Description
Low time start condition (Master only)
Unit time long (Master and iC-TW3)
Unit time short (Master and iC-TW3)
Delay on register read (iC-TW3 only)
Interface idle before next access
Access was write to external EEPROM
Access was not write to external EEPROM
min
1 ms
t_short + 10 µs
35 µs
35 µs
8 ms
3 ms
Table 7: 1-Wire interface timing
max
400 µs
t_long - 10 µs