I don't believe that it is possible to change the frequency of the sensor, because it has a separate chip on it that regulates this. This is great for simplifying your arduino code, but without somehow flashing that chip with altered code, it's likely to be stuck with that freq! You may try to get ahold of the manufacturer about this, but it seems like a long shot.
In the firmware that we are using in our project, there is a small delay between each sensor pings, essentially putting a few microseconds between each pulse within the overall loop. This seems ok for now, but I will be doing hardcore testing within the next few days, so I will let you know better after then.
~Kyle
On 6/5/07, Marko Timlin susi@timlin.de wrote:
hi kyle hi marius, I used the different delay times in the arduino code to avoid crosstalking between the sensors. my idea was: when the arduino board checks the response of the sensor signals after different time intervals each individual sensor won´t react to signals from other sensors. but seems that this doesn`t work. is it possible to assign a different frequency to each sensor, so the sensors can be placed quite close to each other? I play them with "my hands" so they are quite close to each other, approximately around 23 centimeters of distance.
Best, Marko
Yes, please describe the physical configuration of the 5 sensors Marko. I am working on a similar project using 6 sensors, but we have not done much testing in our proper configuration yet.
My guess is that since all the sensors are hard wired with a specific ping frequency, they will detect each other's pings when placed in close proximity.
~Kyle
On 6/3/07, marius schebella marius.schebella@gmail.com wrote:
Hi,
your code and patch look good. It is not clear to me, why you are using these delaytimes for the different sensors. but that should not affect your results anyway. the minimum delaytime between two measurements is only 200microseconds. but maybe it also depends on the length of the impulse? would it be possible, that the sensing fields of the 5 sensors overlap, and you get the crosstalk from that? on the other hand, it may also be possible that the problem is in your circuit. you could try to use 10k pulldown resistors. maybe that stops the crosstalk.
marius.
Marko Timlin wrote:
I am working with several ultra sound sensors called Ping from Parallax wired to an Arduino board that is connected to puredata. currently I am working with 3 sensors and it works fine.
now I want to work with 5 sensors and the following problem occurs:
- I get "phantom" values on sensors that are not modified: if, for example,
I change the value of sensor B, sensor C also changes its values, not exactely syncronized but it jumps to a simlar value range. very annoying indeed.
is that a problem of my script for arduino or a problem of pd? does anybody already have experience with such a configuration? I am using Pd version 0.39.2-extended-RC1 on windows xp.
attached you find the arduino and pd patch for that idea.
thanks, marko
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