dsdx015a2r Sensortechnics GmbH, dsdx015a2r Datasheet - Page 5

• Manufacturer Part Number: dsdx015a2r
• Description: Digital Pressure Transducers
• Manufacturer: Sensortechnics GmbH

INTRODUCTION
The DSDX is capable to generate a digital output signal. It
runs a cyclic program, which will store a corrected 12-bit
sensor value about every 10 ms within the output registers
of the internal ASIC. In order to use the pressure transducer
for digital signal readout, the device should be connected
to a bidirectional I²C-bus.
According to the I²C-bus communication specification, the
bus is controlled by a master device, which generates the
clock signal, controls the bus access and generates START
and STOP conditions. The DSDX is designed to work as a
slave, hence it will only respond to requests from a master
device.
The I²C-bus master-slave concept requires a unique
address for each device. The DSDX has a hard coded slave
address (1111000xb), therefore it is not possible to access
more than one DSDX on the same I²C-bus line.
DIGITAL I
The DSDX complies with the following protocol (FIGURE I):
Bus not busy: During idle periods both data line (SDA) and
START condition (S): HIGH to LOW transition of SDA line
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clock line (SCL) remain HIGH.
while clock (SCL) is HIGH is interpreted as START con-
dition. START conditions are always generated by the
master. Each request for the current pressure value must
be initiated with a START.
SCL
SDA
S
Slave Address
2
C INTERFACE
START
condition
generated by master
generated by slave
R/W
Read out of pressure value
1
A
FIGURE I: I²C-BUS Protocol of DSDX
Data Byte 1
Data
valid
S = START condition
A = Acknowledge
P = STOP condition
Data allowed
to change
A
Data Byte 2
STOP condition (P): LOW to HIGH transition of SDA line while
DATA valid (D): State of data line represents valid data when,
Acknowledge (A): Data is transferred in pieces of 8 bits
Slave address: Each device connected to the bus has a
DATA operation: The DSDX starts to send 2 data bytes containing
clock (SCL) is HIGH determines STOP condition. STOP
conditions are always generated by the master. More than
one request for the current pressure value can be trans-
mitted without generation of intermediate STOP condition.
after START condition, data line is stable for duration of
HIGH period of clock signal. Data on line must be
changed during LOW period of clock signal. There is
one clock pulse per bit of data.
(1 byte) on serial bus, MSB first. After each byte receiving
device – whether master or slave – is obliged to pull
data line LOW as acknowledge for reception of data.
Master must generate an extra clock pulse for this pur-
pose. When acknowledge is missed, slave transmitter
becomes inactive. It is on master either to send last com-
mand again or to generate STOP condition in that case.
unique slave address. After generating a START con-
dition, the master has to transmit the slave address for
the DSDX with a READ command: $F1. The DSDX must
not be accessed with a WRITE command ($F0) as the
correct function of the device can not be guaranteed in
this case (note: a power-down power-up change will
force the sensor to use factory data again).
the current pressure value placed in the output registers.
Digital pressure transducers
Data Byte 2 = Low Byte (LSB last)
Data Byte 1 = High Byte (MSB first)
S
Slave Address
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Next command
DSDX Series
STOP
condition
P
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