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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Average current consumption is reasonable datasheeh less than 50mA and typically about 30mA. You have that long to turn the trigger pin around and make it an input and to have your pulse measuring code ready. Up adtasheet 1mS depending on when you decide it has stopped.

The output of the amplifier srf04 datasheet fed into an LM comparator. The echo line is therefore a pulse whose width srf04 datasheet proportional to the distance to the object.

In this case datasheft can connect the “do not connect” pin to ground and give it an extra uS to srf04 datasheet there. The beam pattern of the SRF05 is conical with the width of the beam being a function of the surface area of the transducers and is fixed. Since the echo output is not raised srf0 the burst is completed, there is no change to the range timing, but the srf04 datasheet delay gives the Picaxe time to sort out which pin to look at and start doing so.

The PIC16F’s programming pins are srf04 datasheet used for other functions on the SRF05, so make sure you don’t connect anything to these pins, src04 you will disrupt the srf04 datasheet operation. The connections to the SRF04 are shown below:. Performance of this design is, I think, srrf04 good. To make matters worse the piezo transducer is a mechanical object that srf04 datasheet resonating some time after the drive has been removed.

This is close the 25 maximum gain available using the LM The 10uF capacitor C9 holds the negative rail just long enough to do this. The beam pattern of the SRF04 is conical with the width of the beam being a function of the surface area of the srf04 datasheet and is fixed. If nothing is detected then the SRF05 will lower its echo line anyway after about 30mS.


To use this mode, just leave the mode pin unconnected – the SRF05 has an internal pull up resistor on this pin. The new code has shipped in all SRF04’s since the end of April These changes have happened over a period of time. The width of this pulse represents the flight time of the sonic burst.

Although the SRF04 works with the BS2, the echo line needs to be connected to the lower numbered input pins. A convenient negative srf04 datasheet for the op-amp and comparator is generated by the MAX This connection is the PIC’s Vpp line used to program srf04 datasheet chip after assembly.

Srf04 datasheet beam srf04 datasheet and beam width You can’t! The SRF04 was designed to be just as srf04 datasheet to use srf04 datasheet the Polaroid sonar, requiring a short trigger pulse and providing an echo pulse.

You srf04 datasheet need to supply a short 10uS pulse to the trigger input to start the ranging. It then listens for an echo, and as soon as it detects one it lowers the echo line again.

The other set srf40 5 pins Srf04 datasheet 5 pins marked “programming pins” are used once only during manufacture to program the Flash memory on the PIC16F chip. The transducer can handle 20v of drive, so I decided to get up close to this level. The input capacitor C8 blocks some residual DC which always seems to be present.

The SRF04 provides an echo pulse proportional to distance. This is a question which crops up regularly, however there is no easy way to reduce or change srf04 datasheet beam width that Srf04 datasheet aware of.

SRF05 Technical Documentation

The gain bandwidth product srf04 datasheet the LM is 1Mhz. The raising of the echo line also shuts of the MAX This is because the Stamps take progressively longer to look at the higher numbered pins and can miss the rising edge of the echo signal.


A new operating mode tying the mode pin datazheet ground allows the SRF05 to use a single pin for both trigger and echo, thereby saving valuable pins on your controller. Srf04 datasheet SRF05 can be triggered srf04 datasheet fast as every 50mS, or 20 times each second.

It is much harder to tell the difference between this direct coupled ringing srf04 datasheet a returning echo, which is why many designs, including the Polaroid module, simply blank out this period. If the width of the pulse is measured in uS, then dividing by 58 will give you the distance in cm, or dividing by ssrf04 give the distance in inches.

The circuit is designed to be low cost. This is to ensure the ultrasonic “beep” has faded away and will not srf04 datasheet a false echo on the next ranging.

It then listens for an echo, and as soon datasheey it detects one it lowers the echo line again. The receiver is a classic two stage op-amp circuit. Update – May Since the original design of the SRF04 was published, there have been incremental improvements to improve performance srf04 datasheet manufacturing srf04 datasheet.

Maximum range is a little over 3m. The echo signal will appear on the same pin as the trigger signal. The SRF04 will send out an 8 cycle burst of srf04 datasheet at 40khz and raise its echo line high. It then generates just eight cycles of 40khz. It has a number srf04 datasheet disadvantages for use in small robots etc.

Range is increased from 3 meters to 4 meters.

Devantech SRF04 Sonar Ranging Module

srf04 datasheet This project started after I looked at the Polaroid Ultrasonic Ranging module. The beam pattern of the transducers used on the SRF04, taken from the manufacturers data sheet, is shown below.

All SRF04’s manufactured after May have new software implementing an optional dataaheet control input srf04 datasheet the “do not connect” pin.