SRF04 Ultrasonic Range Finder. 30th September Introduction. The Devantech SRF04 Utrasonic Range Finder of- fers precise ranging information from. 28 Jan SRF04 datasheet. Description: The SRF04 was designed to be just as easy to use as the Polaroid sonar, requiring a short trigger pulse and. The Devantech SRF04 ultrasonic range finder provides precise, non-contact distance measurements from about 3 cm ( inches) to 3 meters ( yards).

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To make matters worse the piezo transducer is a mechanical object that keeps resonating some time after the drive has dxtasheet removed. This is a question which crops up regularly, however there srf04 datasheet no easy way to reduce or change the beam width that Srf04 datasheet aware of. After programming its just an unused input with a pull-up resistor.

The srf04 datasheet is designed to be low cost. Mode 2 – Single pin for both Trigger and Echo This mode uses a single srf04 datasheet for both Trigger and Echo signals, and is designed to save valuable pins on embedded controllers.

Devantech SRF04 Sonar Ranging Module

If the width of src04 pulse is measured in uS, then dividing by 58 will give you the distance in cm, or dividing by will give the distance in inches.

The beam pattern of the SRF05 is conical srf04 datasheet the width of the beam being a function of the surface area of srf04 datasheet transducers and is fixed.

The receiver is a classic two stage srf04 datasheet circuit. A small amount of positive feedback provides some hysterisis to give a clean stable output. The echo line is then raised to signal the srf04 datasheet processor to start timing. I therefore shut it down whilst listening for the echo. To use this mode, just leave the mode pin unconnected – the SRF05 has an internal pull up resistor on this pin.


It has a number datawheet disadvantages for use in small robots etc. It is much harder to tell the src04 between this direct coupled ringing and a returning echo, which is why many designs, including the Polaroid module, simply blank out this period.

It then listens for an echo, and as soon as it srf04 datasheet one it lowers the echo line again. With the timing pin pulled low grounded a uS delay is added between srf04 datasheet end of the srf04 datasheet pulse and transmitting the sonic burst.

SRF05 Technical Documentation

In operation, the processor waits for an active low trigger pulse to come in. Average current consumption is reasonable at less than 50mA and typically about 30mA.

The SRF04 was designed to be just as easy to use as the Srf04 datasheet sonar, requiring a short trigger srf04 datasheet and providing an echo pulse.

The 5v drive can give a useful range for large objects, but can be problematic detecting smaller daatsheet. Range is increased srf04 datasheet 3 meters to 4 meters. The SRF04’s “do not connect” pin now acts as a timing control. The 10uF capacitor is now 22uF and a few resistor datasneet have been tweaked.

If nothing is detected then the SRF04 will lower its echo line anyway after about 36mS.

Although the SRF04 works with the BS2, the echo line needs to be connected to the lower numbered input pins. The SRF04 provides an echo pulse proportional to distance. The other set of 5 pins The 5 pins marked “programming pins” are used once only during srf04 datasheet to program the Flash memory on the PIC16F chip. You should wait 50ms before the next trigger, even if the SRF05 detects a close object and srf04 datasheet echo pulse is shorter.


You only need to supply srf04 datasheet short 10uS pulse to the trigger input to start the ranging. The echo line is therefore a pulse whose width is srf04 datasheet to the distance to the object. The new code has shipped in all SRF04’s since the end of April Performance of this design is, I think, quite good. This is to ensure the ultrasonic “beep” has faded away and will not cause a false echo on srf04 datasheet next ranging.

Introduction The SRF05 is an evolutionary step from the SRF04, and has been designed to increase flexibility, increase range, and to reduce costs still further. It then generates just eight cycles of 40khz. Unfortunately, this also srf04 datasheet quite a bit of high frequency noise. Datashwet srf04 datasheet bandwidth product for the LM is 1Mhz.

Looking at the returning echo on an oscilloscope shows that it is much larger in magnitude at close quarters than the cross-coupled signal. The Datasgeet programming pins are also used for other functions on the SRF05, so make sure you don’t connect anything to these pins, or you will disrupt the modules operation.

SRF04 Technical Documentation

To use srf04 datasheet mode, connect the mode pin srf04 datasheet the 0v Ground pin. The SRF05 will send out an 8 cycle burst of ultrasound srf04 datasheet 40khz and raise datasheef echo line high or trigger line in mode 2. It uses a PIC12C to perform the control functions and standard 40khz piezo transducers.

As and example of the sensitivity of this design, it will detect a 1inch thick plastic broom handle at 2.