[Lab] leads on an ultrasonic range finder
klmckinnon at rogers.com
Tue Feb 11 17:28:51 EST 2014
Sounds like a pretty elegant solution.
On 2014-02-11 1:24 PM, Adam Hill wrote:
> I can confirm Ken's suspicions, at least anecdotally. I was not able
> to do a lot of debugging at the time, but when I tried using long
> leads with a similar sensor it was completely unreliable. Instead of
> fighting with physics, my solution was to go wireless. I created an
> adhoc network with an airport express and connected a beagle bone to
> the network which was close to the proximity sensor. That gave me the
> effective range of the wifi network while keeping the sensor
> components close to the data collection hardware.
> Best of luck,
> On Mon, Feb 10, 2014 at 7:44 PM, Ken McKinnon <klmckinnon at rogers.com
> <mailto:klmckinnon at rogers.com>> wrote:
> If your talking a SRF04 or similar, there are a couple of issues
> you need to consider. These are driven at 5VDC, and use a chunk
> of current while transmitting the sensor pulse chain. On a long
> lead, you may have voltage droop on the 5V line at the sensor
> end. The result may be that the sensor resets, doesn'r respond
> correctly or somewhere in between (read errattic behaviour - the
> worst). This likely may be mitigated with a decent sized cap
> between VCC and ground at the transducer/sensor.
> The trigger is a 10 usec pulse. On a long lead, this can become
> rounded due to the capacitance of the cable, so a start pulse may
> not be seen. The same goes with the recieve pulse, although since
> it is longer, it is unlikely to cause any problems.
> If I were to try this, I would use a reasonably heavy guage cable,
> say 24 AWG or better, shielding will help, but twisted won't as
> the signals are single ended. If it doesn't work, tack solder a
> 47 uf cap between VCC/Ground and try it. If that doesn't work,
> it gets a bit more complicated....
> On 2014-02-10 4:58 PM, Darcy Whyte wrote:
>> Can anybody think of a reason I shouldn't have 10' wires on an
>> ultrasonic range finder?
>> Darcy Whyte
>> Art+ inventorArtist.com <http://inventorartist.com/> | Aviation
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>> Contact: darcy at inventorArtist.com
>> <mailto:darcy at inventorArtist.com> | 613-563-3634
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