Mutliple inputs

Forum 2005-2010 (read only) Hardware Troubleshooting
21

It sound like you have verified that the arduino inputs are reading correctly so the problem is in the wiring to the sensor, or with the sensor itself.

To double check this you can adjust the pot for a voltage of say 0.04 volts between the center pin and Gnd. Run the sketch and note this reading ( it should be something a little less than 10). If you then wire the pin to the sensor instead of the pot (and confirm the voltage on the arduino pin and gnd is still around 0.04 volts) then you should get a similar reading as with the pot.

22

I see your logic in that but when I used the two potentiometers as voltage dividers instead of the sensor, why would they both not have registered right. One of them registered completely off and the other registered just fine.

23

I interpreted your post #16 as saying that they both registered just fine.

Without the sensor, just using one or two potentiometers, can you get correct readings on two analog pins?

24

So yeah that is why I am a little confused. When I hooked up the two inputs, from the same source, they registered the same value. But when I hooked up to separate potentiometers to the arduino registered one correctly and the other completely off.

25

How did you hook up the two potentiometers? They should be wired so that the center pin of each pot goes to a seperate analog input but the end connection on the pot should be wired the same – one end of each pot goes to +5v, the other end of each pot goes to ground.

If you can't get that give you reasonable readings then post a picture of the setup.

26

Alright I am sorry. I mixed up one ground line on the two POTs and got the right results. I switched back to the stereo line in and still got the same problems. For some reason there is something screwy with the set up for it. What i am doing is reading one side off of the stereo jack. It is grounded and i have checked the continuity through the whole circuit. I have a diode and then a 120K resistor and then the input into analog input 0. The diode is a simple 1N914 type diode from radio shack. I am using that to keep the voltage continuously positive. I felt the diode would be large enough. The stereo input is affecting the circuit for some odd reason. Here is some pictures:

27

What are you connecting to the jack and what is the maximum voltage that it produces?
How did you arrive at 120k for the value of the resistor?

28

From a brief skim it sounds like you may have two different ground sources?

29

it sounds like you may have two different ground sources?

Looking at the closeup pic in pos #25 it does look like the black wire is not plugged into the pin connected to the jack ground.