Ultrasonic Ranger only as Receiver/ Sender?


#1

Hi,
I’m new to the forum and I’m planing a school project where I need some advice :). But first a question. Is it possible to use the Ultrasonic Ranger v1.0 only as a sender and another two or three only as receivers? Because I want to make a sort of positioning system with ultrasound. So that’s why I need a sender and receivers.
And do you need the GrovePi in order to hook the Ultrasonic Ranger up to the Raspberry Pi? Because I’ve seen projects where they’ve used older versions of the Ultrasonic Ranger and it worked for them without the GrovePi. But with the newer version (v1.0) it seems to be a bit tricky with wiring.
Many thanks in advance.


#2

Hey,
We have not tried using ultrasound sensor as a sender receiver pair but it might be possible with careful calibration. I think that it would be better to find if someone has successfully done it with Arduino or any other system and then try to do it on the Pi either via the GrovePi or Arduberry.

There are ways to use the ultrasonic sensor directly with the Raspberry Pi https://www.modmypi.com/blog/hc-sr04-ultrasonic-range-sensor-on-the-raspberry-pi but I am not sure about its accuracy and wheter you would be able to run multiple sensors and the wiring and code look tricky too.

-Karan


#3

Hi Karan

Thank you for your reply. The thing is my ultrasonic ranger is not a hc-sr04, which the link is for and it seems as if it’s not too hard to connect it directly to the Pi with the one I haven’t got… But mine is a Grove Ultrasonic Ranger and as you can see on the picture below it is rather hard to wire and further more I think my product gives me a digital output or “response” but the hc-sr04 should give me a normal voltage in return, which can be processed by the Pi. So I might have to get the hc-sr04 which might make my problem a bit easier to solve, what do you reckon?

cheers
DCJ27


#4

Hey,
I have played a bit with the Ultrasonic sensors and I might be able to help you out a bit. Most of the Blue sensors are either SR04 or some variant of it. The normal ones have 2 data pins, one is connected to the transmitter and the other to the receiver. So you send a signal from the transmitter and start waiting for the pulse to return back and measure the time it took for the signal to come back and calculate the distance from that. The seeed one only has one connection because it is possible to short the two wires directly and use them. There is some information available on the internet for this. The normal ones have the two wires separated so it is easy to manage.

I have never dug that deep into the ultrasonic code, but I think it would be very difficult to achieve what you are trying to do, but I think choosing a Seeed sensor for transmitting and a normal one for receiving might be your best bet. Can you tell me what you are exactly trying to build and why you need two different sensors. I might be able to suggest something else that might work better for you.

-Karan


#5

G’day Karan

Thank you for your reply. I had a look at your link you have sent me before and according to the code you have to “send” the signal and than wait for the response. What if the ultrasound is just coming from a different device then the one receiving it? Couldn’t the first receiver simply wait for the signal to come/rebound (doesn’t matter to the receiver does it?)?

But then I couldn’t really find a wiring instruction, because on my ultrasonic ranger I’ve got:

GND = which is the Ground Pin
UCC/VCC = I can’t quite read if it is a U or a V but most likely it is VCC which would be 5V
NC = which is probably the counter pin to the SIG
SIG = which is probably the signal that comes back

Well my project is a Matura project, which a one last big project at school before I finish school in Switzerland. So I was planing on locating the “sender” with the help of the time difference of the received signals at the “receivers” and then calculate more or less exactly the position of the “sender” in the first place. (So there is a bit of math involved as well, but this should be alright) Initially I wanted to use electric magnetic waves, but as they travel rather fast I opted for sound waves as they are much slower. But it will still be a challenge. So currently my problem is the technical setup…

cheers
DJC27


#6

Hey,
The NC wire is most probably “Not connected” and the other one is the wire which carries the signal.

I don’t have much idea, you can measure the pulse length with the pulseIn() function on arduino. You can use this with some accurate timekeeping to determine the distance. I think checking with an oscilloscope, how the transmitter and receiver react, would be the best way to venture into this.

-Karan


#7

Hi Karan

Thank you for your reply. I might try and get the other ultrasonic sender, hc-sr04, and try it directly with the Raspberry Pi as I haven’t got an arduino. If you’re interested I’ll poste the results.

cheers
DCJ27


#8

Hey,
Do let us know how your project goes.

-Karan


#9

Well I’ve ordered the new ultrasonic senders and it is possible to use one just as a sender and the other one just as a receiver, which a little cheat. You take sender 1 and just send the signal. That is possible, because if you don’t tell him to wait for the returning signal, he just won’t do anything else, but send the signal. Now for the receiver it doesn’t work. They are built in a way that you can’t just wait for the signal, without having sent one before. So you just send one and wait for the response. But this response will be from sender 1 if they face each other, as the signal from the sender 1 reaches sender/receiver 2 in half the time of the returning signal, so it will always pick up the first signal (from sender 1). To get the distance you have to multiply the distance by two, obviously, and you get the distance between the two senders. So yes it is possible with a little cheat and by blocking either the receiver or sender bits on the device

Cheers
DJC27


#10

Hey DJC27,
That does sound really cool. I haven’t heard about someone using the sensors in that kind of a setup but it’ll be awesome if you end up with something that works.

Also, do share your project with us. We have an Instructables contest running too http://www.dexterindustries.com/forum/?topic=pie-day-contest, so you can post your project there and you might end up winning some awesome goodies.

-Karan


#11

Good day DJC27

I’m working on a similar project as you did to use only one sender and multiple receivers for the ultrasonic sensors.
have you figured out how to do it, because in my project i want to have one sender to send a pulse out to two receivers and then calculate the distance and the angle from the sender to the receivers(obviously)

-Armand