Ultrasonic Transceiver obstacle detector

[Shahar Levi]

Hi,

I am trying to build a circuit using the MSP430 Launchpad and an ultrasonic transceiver (the sensor is both transmitting and receiving and has only 2 pins) in order to make an obstacle detector, but unfortunately I am lost.

In the past I have built an ultrasonic circuit with msp430 max232e and a few op amps but then it was with 2 separate sensors - one transmitter and one receiver and it worked great. nevertheless, transceiver is a different case and I don't know where to start. I am pretty new to electronics and I would love to have any hint or even better, schematics.

thanks in advance,

Levi

 

[paulfjujo]

hello,

Look at the specsheet of a HC-SR04 ultrasonic module
With only one sensor you must use an anlog switch ( like CD4051 or HCT4051)
to use your sensor as an emitter : send 8 periodes of signal at 40KHz ( i suppose is your case, or sepecifie if different)
so during 200µS

after you start your Timer for elapsed time measure

then commute your sensor as a receiver
This received signal must be amplified to get a higher level (CMOS or TTL level) + integrateur (RC filter)+ schmitt trigger
to be compatible with your MCU input.
and detect the feed back of ultrasonique wave.
When you get this edge .. you stop your timer.
this time value represents the distance (whis any calculus!)