parking sensor interface

I found multiple links to connect to the control module for a 4 parking sensor array. I have found countless links to ultrasonic range finders but I am coming up short on how to interface the raw 2 wire car parking sensor.

http://www.ebay.com/itm/161268765071

Center frequency (KHz): 40±1.0KHz Echo Sensitivity: ≥200mV Decay Time: ≤1.2ms Directivity (deg ) X-axis: 60±15 Directivity (deg ) Y-axis: 60±15 Capacitance ( pF ): 2000±15% Allowable Maximum Input Voltage ( Vp-p): 140 (40KHz) Pulse width 0.5ms, interval 20ms Mean Time to Failure: 5000h Operating Temperature ( Degree Celsius ): -40~+80 Storage Temperature ( Degree Celsius ): -40~+80 Cable Length: 250 cm Radar Diameter: 22.5 mm Color: Black

A little more digging and I found a board that couples with the wired sensor. Since this is a water level application, the 25cm minimum 'blind spot' is not a problem, I will install high enough to avoid that issue.

http://www.ebay.com/itm/262136734027

this mentions JSN-SR04T and that has some links.

but, I am still hoping for a direct to Arduino connection.

I found a note on using this module, saying it's compatible with the HC-SR04.

I think it is pretty obvious that this is nothing more than a transducer. It has only two pins.

It looks as if it is intended to be used in pairs, connected to the master module with four connectors (partially) illustrated in the fourth picture. One pair on each side of the bumper bar.

I bought two figuring that the web would be rife with all manner of hacks..... no such luck.

the sensor that cost $1.70 is basicaly a 2 pin end, some wire, a housing and in that housing is a piezo can. the aluminum can has he piezo welded to teh front. I assume with some sort of adhesive.

nothing but a simple piezo device.

the board sold for it will blast it with some high voltage pulse and that will send out the ultrasonic wave. the sensor goes dormant, the ringing of the can subsidies. the sensor goes into listening mode.and the electronics listen for the return ping.

in that dormant instant, the sensor is blind. the notes say this is equivalent to about 20cm so the sensor has a blind spot of about 20cm, the literature says 25.

I am coming to the conclusion that if you want one, you get the one with the board for about $15-20

if you want 4, you get the back-up sensor kit that does the 4 sensors. there is a hack to take the readings out of that and turn them into distance per sensor. so, you wind up with 4 readings, even if you only need 1.

and, you have to mount the sensor at least 25cm from wherever you want your zero distance. in my case, 25cm above the sump pump pit. in my case, the floor.