Wemos d1 mini + blynk + waterproof ultrasonic sensor ( ebay car backup sensor)

Hey guys,

Top of the morning to you. I am planning to work on a project to monitor the level on my basement sump. Recently while I was in my basement I did a random check on my sump pump operation by bypassing level switch and the pump didnt come on. so I opened the lid on the tank to find the level on my sump about 1/2 inch from flooding. I replaced the sump pump with new one and level is back to normal. Hence the need for this project.

I ordered a few of these car backup parking sensor from ebay since they are waterproof (https://www.ebay.com/itm/22-5mm-Black-New-Parking-Sensor-Car-Reverse-Back-Up-Ultrasonic-Radar-DPL5-Top/222768942440?hash=item33de104d68:g:RRcAAOSwpdpVelBL) since HC-sr04 module are not waterproof. However after receiving them I realized they only have two pin versus the four pin on hc-sr04. Therefore I need some help to first read the data over serial monitor by hooking up the ebay waterpoof sensor to wemos d1 mini.

Once I am able to read them then I can starting coding in Blynk and update you on my progress.

Since you are new to the community…

A quick google search of that sensor, and i see that most of them come with an additional circuit board. Upon further investigation, the pictures of said board appears to have a two pin socket for the sensor, and the familiar 4 pin scheme of the HC-SR04. In fact there are some markings on the board that show jsn-sr04, and a quick google search of that reveals a lot of information on that sensor. Even some example code.

I will leave the rest up to you, but think you will not have much success without that additional board.

Google is your friend.

Yes, I’d say that getting a JSN-SN04T sensor which is waterproof could save you a lot of pain in the long run.


Wouldn’t be too difficult to change things to suit your sensor.

the sensor shown in the image is not waterproof. I am looking for something thats waterproof so i bought the same sensors that come with car as parking sensors. however i dont know how to read data from them over serial

no such sensor as JSN-SN04T. are u sure thats right model#?

Did you read my post?

Looks like he made a simple typo.


With or without the T I get a lot of results.

Also if I try JSN-SN04T in google, it corrects you to JSN-SR04T

he means these:


Seems not much has changed around here.

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yes sorry i read it but in hurry. okay i will buy that module and wait for now since it probably takes 1 month to arrive from ebay china.

Sorry for bumping up an old question but I’m in the same boat of requirement.

And to my surprise there are quite a few new sensors in town:

This one has 2 transducers instead of 1 therefore has less minimum detection distance as compared to JSN SR04T. It is also completely sealed and waterproof.


Before finalizing on this I had bought another one which was a waterproof modified version of HC-SR04 from here


The 1st one is much more rugged and waterproof as compared to the latter one.

There are ultrasonic sensors and ultrasonic sensor boards… some are all in one and will interface with an MCU, others are just the transducers and need the control circuitry (sold separately) to even work. And yet others may be proprietary and may not interface with any MCU.

Since none of that is Blynk specific (as in Blynk doesn’t control or read directly from the sensor anyhow), I recommend you Google for basic Arduino use of each type you look up. If you can Arduino find code for it, then it can be adapted to Blynk for the interface.

Personally the HC-SR04 waterproof ultrasonic sensor looks like a basic HC-SR04 in a waterproof casement, so should work nicely with normal Arduino code. I have something here to use as an example

The other one is hard to tell what it is…

Thanks for the example!

The other one seems to be a totally new sensor meant as a replacement for JSN-SR04T. (That’s my assumption). It tries to fix the issues present with JSN SR04T of smaller blind distance and complete waterproof-ness.

And for that other new sensor, I did find Arduino Uno Code in the ebay description.

It points to this link

Arduino Uno Code for DYP-A02YYxx v1.0

At US $ 27.99 I’d expect more than just a code example. I’d be looking for the guy to come around and install it all as well :slightly_smiling_face:



or at least to sent also some sandwiches and beers !


Haha. I did find it cheaper than $99+ maxbotix sensors. So there’s that. :sweat_smile:

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Robo-craze is a spam account. They have posted the same fake advice in multiple forums, including Cayenne MyDevices and MySensors.

Their products might not be bad, but be aware that they are masking marketing as advice.