Problems with sensors and cables

Hi all,

I have a problem with my project. I have different sensors to measure environmental data. 2 of them are a TSL235R to measure light intensity by the use of Frequency Counter Library on digital pin 5. The other is a QR1114 IR sensor what control an anemometer. It is connected to digital pin 3 and it use interrupts to count the revolutions.

Each one is wire by a ribbon cable to the arduino duemilanove, and they runs perfectly. The problem appear when i connect all the sensors (those and others) trough a 8-wires cable to arduino. Results from the QR1114 climb a lot! When the TSL235R is unplugged, the reply becaomes correct again... So it seems that the signal through both wires couple sin some way. For that reason i changed the cable to other cable with 8-shielded wires (they are shielded 2 by 2). i connected only the 2 problematic sensors to 2 different packs to have shields in between... and the problem persist!

So, i am coming crazy because i don´t know what could be the problem... i could still use different cables for each sensor, but it multiple the cables that i require and it made more complex the design and more ugly the final result.

Any idea or proposal?
Thanks guys!


I think you need to post more information for any usefull ideas. It seems really counter intuitive, that there should be interference with ribbon cables, but not with individual cables (as they would probably be close together as well, right?

what are “all the sensors (those and others)” ? is there anything more going on than just those 3 sensors you mentioned?

How do you power your sensors?

Maybe you could post a picture of the connectors, both ends of the ribbon cable - I’d be interested in seeing it. I feel like its probably something really obvious, that went unnoticed, becouse its so obvious… you know what I mean.

good luck


Thanks fkeel,

Tomorrow i will take some pictures to show the connector and the sensors.

In really, i have more than those sensors. My project include: LDR, TSL235R, QR1114, SH15. All of them have wires (independant ribbon cable for each sensor) , and codes what runs perfectly each one of them, but also when they are connected to arduino duemilanove.

The problem started when i removed the ribbon cables and connected all the sensor to a unique cable (8-wires). All the combinations runs ok, except when the QR1114 and the TSL235R are connected at the same time. So the problem seems to be in some way of coupling, but also when the 8-wire cable have individual shields for each couple of cables!...

The webpage where i have the description of the project is this one:
however, it does not include all the information about the sensors and problems that i report here.
Here is described these two sensors (sorry, in spanish, but you can see the diagrams and the complete arduino code):

Tomorrow i will try to have more information to post here.

Tomorrow i will take some pictures to show the connector and the sensors.

It would help a lot more if you posted a schematic.

Yes, Grumpy_Mike. I will prepare an sketch with fritzing, and post it to show you all the sensors and the individual circuits for each one, and all the connections.

For the moment: here is the previous discussions about code related to TSL235R:

and the QR1114 for the anemometer:


Problem sounds like cross-talk. How long are the cables? Is every signal line next to a ground line all the way?

Hi MarkT,

I think that the problem is not the longitude of wires, because i supposed it was the problem, and i tried with a short piece of cable of only 15 cm... and the problem was still there in the same way that in a 1.5 meters long cable.

The cable have a ground line, what are near to all the others... i tried also connecting the shield of the cable to ground...

I will try to post here some pictures to show you everything...

Thanks for your interest!

hi, thank you very much for the answers :slight_smile: :slight_smile: