The pinout is the same, and it’s essentially a drop-in replacement for the HC-SR04. In Mode 0, which is the default mode, the sensor operates as a replacement for the popular HC-SR04 ultrasonic distance sensor. The six modes that the JSN-SRT04T can operate in are as follows: Mode 0 – HC-SR04 Emulation Modes 3, 4, and 5 are selected by placing a resistor across some traces on the PCB.Modes 1 and 2 are selected by bridging some traces on the front of the PCB.Mode 0 is how the sensor is configured when you buy it, no need to do anything.Mode selection is accomplished in two ways: The sensor, which is a single device that acts as both transmitter and receiver, is attached to the PCB using a 2-meter cable.Īnother interesting aspect of the JSN-SRT04T is that it can be run in six different operating modes. The JSN-SR04T is an interesting sensor in that it comes as a separate printed circuit board and sensor unit.
Of course, you could add this feature in your own sketches if you wish.
It’s possible to use additional sensors to factor that in, as we did in the HC-SR04 article, but we aren’t doing that today. Note that the speed of sound is not a constant, it can vary due to air pressure, temperature, and humidity. You then multiply the speed of sound, 343 meters per second, by the time delay to see how far the object that reflected the sound is from the transducer. To calculate the distance, you first need to divide the time delay in half, as it represents the back-and-forth travel of the ultrasonic pulses. This time delay can be used to compute the distance to the object that reflected the sound. If they do, then the time delay between transmission and reception is measured. In operation, the sensor transmits pulses of ultrasonic sound and then listens to see if they get reflected back. Others, like the JSN-SRT04T, employ only one transducer which can serve as either a transmitter or receiver. Some, like the HC-SR04 or A02YYUW, use a separate transducer to send and receive pulses of sound. Ultrasonic distance sensors employ transducers that can work at ultrasonic frequencies, usually 40KHz. Two common examples of transducers are microphones and speakers. The operation of these sensors is summarized as follows: TransducersĪ “transducer” is a fancy name for a device that can either convert mechanical vibrations into electrical energy or convert electrical energy into mechanical vibrations. If you want a complete description of the operation of ultrasonic sensors, then please check out the article and video I did on the HC-SR04. However, they both use the same principle of operation. The two sensors that we are looking at today, the JSN-SRT04T and the A0YYUW, look quite different from one another. Let’s take a look at two of these sensors and see how they work. And while they definitely are not as cheap as the HC-SR04, they are not all that expensive. You can use these sensors to build outdoor robots, detect intruders, or serve as a backup alarm for your vehicle. You can get them wet, and they will still keep working, and they are also impervious to dust and dirt. Even sealing up its circuit board would not protect it, as the two transducers it uses are essentially just small speaker/microphones.īut have no fear, there are several ultrasonic distance sensors that do indeed work in harsh environments. It is a pretty fragile device and can easily be damaged by dirt, or even high winds. However, using the HC-SR04 outside is a different story. That is, as long as you are using it indoors.
For collision avoidance robots or intruder detection, this sensor is usually all you’ll need. It is pretty easy to use, it performs well, and it is very inexpensive. We have used the HC-SR04 Ultrasonic Distance Sensor many times here in the DroneBot Workshop and for many good reasons. Unlike the ultrasonic distance sensors we’ve used previously, these devices are waterproof.
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