Presence detector and rangefinder

Presence detector and rangefinder

DW0050 is an electronic module which makes use of ultrasound technology in order to recognise the presence of a surface by measuring the distance up to some tens of centimeters. The module DW0050 is a digital sensor designed to maximise the sensitivity. It is able to detect small objects also. Moreover, it is recommended to compose a system using multiple modules DW0050 sharing a wired interface based on a digital serial bus. In doing so, the modules will cooperate in order to detect the presence of objects (see DW0050 detector application note).

Wired interface description

The interface present on each module consists of two 5-pin molex connectors 180°. A connector connects the module with the MASTER board that receives the signal detection of the obstacle. The other connector, with the same pin-out, can be used to connect another module DW0050. Thus more modules can be connected in cascade which can collaborate in identifying the presence of obstacles. When the detection pin is driven to a low logic level means that an obstacle has been detected. This same pin can be used as a LIN bus full duplex communication for a more complex interaction between the MASTER board and the module DW0050. To use the LIN bus is needed to 1kΩ pullup. The MASTER board can drive an optional trigger signal to start the measurement. To be considered valid, the trigger signal should be active for at least 250us while the minimum period of measurement is 30ms.

Measure for the detection of the obstacle

The measure that leads to the identification or not of an obstacle in the cone of coverage of the sensor is made ​​by transmitting a burst of ultrasound and measuring the amount of reflected energy, from any obstacle, which go back to the sensor. The DW0050 module supports two modes: “thru-beam” and “single reflective sensor (SSR).” For each trigger signal, when used, is made a single measure. A signal FLAG is activated if three consecutive measurements indicate the presence of an obstacle. The DW0050 module also implements a calibration algorithm to exploit the ultrasonic sensor / transmitter. Thanks to this type of devices the sensor can be used in environments with high electromagnetic noise.

Module specifications

Specifications Description
Mechanical Dimensions 65mm (L) x 25mm (W) x 19mm (H) IP65 ready
Frequency 40kHz ± 1kHz
Directivity 35 degrees ± 7 degrees respect sensor’s azimuth
Temperature Operating -40°C to 80°CStorage -40°C to 85°C
Sensitivity In single sensor reflective mode recognizes a glass board 10cm x 10cm x 1cm at 1 meter distance
Voltage level Nominal Vcc = 12V ± 10%
Power Typical 400mW with Vcc = 12V
Trigger levels Typical threshold 6V with hysteresis 1.3VActive between 250us and 2msMinimum period 30ms (see application note)

Applications

  • Agricultural machinery;
  • Industrial;
  • Automation;
  • Domotics;
  • On road barriers detecting the presence of an obstacle.

Detection distance

Detection distance can be changed using a on module dip switch.

Dip-switch statusDP1; DP0 Detection distance range
ON; ON 10 cm to 94cm
ON; OFF 10cm to 84.0cm
OFF; ON 10cm to 79.0cm
OFF; OFF 10cm to 74.0cm

PIN-OUT description

PIN Description Direction
1 Supply voltage (Vcc=+12V) IN
2 Supply reference (0V) IN
3* Detection OUT
3* LIN bus IN/OUT
4 Trigger IN
5 EARTH connection IN

* mutually exclusive

 

Download datasheet

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Posted on

05/07/2014