Sporadic and/or Broken Analog Pins on Arduino UNO R3

Projects General Guidance
1

Hi Guys,

This is my first post ever! Excited to be a part of the community.

I just got my Arduino UNO R3 board about a week ago. A couple days after I got it, the analog pins started returning random/sporadic values. I thought this was odd so I went ahead and ordered a new chip and placed it in. I just got the chip in the mail and I stuck in the board and it still has the same problem. Is there anyway I can fix this or do I need a new board? What could have caused this? I don't THINK I did anything that would have messed up the board. But then again I am not sure....

All help is appreciated.
Thanks!

2

Welcome to the Arduino community!

Please describe how you have wired up the analog pins, and show what code you are using to read them.

I assume this isn't an installation issue, so I will move it to Project Guidance.

3

Welcome.
I got my Arduino November 2012 and have found it to be a very interesting product.

If these pins have nothing connected to them then this is called a floating I/P.
You normally have the pins connected to something.
Place a 10K resistor on the analog I/P to ground and see if things change.

4

I have tried using the resistor and my R3 just reports back all 0's for the read on a pressure sensor. When i take the ground out i get random numbers then the numbers spike to 1023 (HIGH) no matter if i touch it lightly or slam the f%%%%%% thing on the desk. This problem is getting on my nerves, i follow the arduino diagrams exactly and even use their code and i get the same crummy results

5

You haven't shown us (the link to) the pressure sensor or posted the actual code you are using (in "code" tags), you haven't provided a (accurately focused in resolution 1024/768 or less) photo of your rig, so we really have no idea what you are actually doing.

6

Sorry, I read over this tutorial on the Arduino website ( http://arduino.cc/en/Tutorial/AnalogInput ) and instead of a photo resistor i used a pressure sensor like the one seen on this page ( https://www.sparkfun.com/tutorials/389 ). I then just had the Arduino board take the sensor value and print it to the serial monitor. I noticed that the numbers are all wacky, but when i do lightly tap the sensor the value jumps to 1023 and then slowly trickles down by 50 to its original number and then fluctuates again. I have used these things before, i have done this programming before and got it to work with the same equipment. Its frustrating how elementary this seems but yet I cant get it to work.
I am not sure if this means anything but i did notice that I can burn a new bootloader on to my ATTINY devices but i can not burn the bootloader to my R3. Not sure if i am supposed to be able to or not but i thought i may as well throw it in there.
Thanks for the help!

7

TWeiss33:
I have tried using the resistor and my R3 just reports back all 0's for the read on a pressure sensor. When i take the ground out i get random numbers then the numbers spike to 1023 (HIGH) no matter if i touch it lightly or slam the f%%%%%% thing on the desk. This problem is getting on my nerves, i follow the arduino diagrams exactly and even use their code and i get the same crummy results

Are you the same person who started this thread? If so, you still haven't shown us your hardware or software and it's pointless asking for more help until you do that.

If you're a different person then I have no idea what project you're talking about - there's no way to help you until you tell us what the problem is.

8

No i am not the same person who started this thread i am just a person who was having the same problem as the person who started this thread. I do not have a project i am working on, all i am trying to do is get good readings from this pressure sensor. Values that are consistent or only off by 1 or 2 with the same force applied. what it is doing now is spitting out a bunch of values that vary by 200-400, and then when i put the slightest pressure on the sensor it immediately jumps to 1023 and then slowly trickels back down.

9

The only thing your problem has in common with the original one this thread is about is that you're getting unexpected analog input results. Presumably this is because of a hardware or software fault in your project. If you want anything less vague than that then you need to tell us what hardware and software you're using - circuit diagrams, and links to data sheets for any unusual components you're using, and a copy of the sketch, links to any non-standard libraries you're using, a description of what you expected to happen and what actually happened.

10 
The only thing your problem has in common with the original one this thread is about is that you're getting unexpected analog input results.

exactly, that is why I posted it here, I am having the same problem as he is with analog values? there is no project? all i am trying to do is get accurate analog readings of this pressure sensor on my serial monitor.

If you want anything less vague than that then you need to tell us what hardware and software you're using - circuit diagrams, and links to data sheets for any unusual components you're using, and a copy of the sketch, links to any non-standard libraries you're using, a description of what you expected to happen and what actually happened.

um, I included the website that i was following exactly. The website has all the diagrams and such. I am not sure what else is needed/ There is no need for a data sheet there are no tricky components its just a 10k resistor, pressure sensor (came with arduino kit) and an arduino board, all of which i listed in my description of my problem that included links.

11

You've linked to two different projects, and I'm not sure which one you're using or how closely you have followed the instructions. The symptoms could easily be produced by a floating input which could be caused by a wiring design fault or poor connection. To avoid ambiguity, I suggest you post the actual code you're running and a picture of your hardware setup with enough detail to see what components you're using and how they are connected.

12

Here are some pictures of my wiring https://www.flickr.com/photos/124307266@N02/
The yellow extension wires are not the problem because i tried using my other pressure sensor without extensions and it still didn't work

Here is my code, pretty simple so I assume this is not the problem

void setup(){
  pinMode(A5, INPUT);
  Serial.begin(9600);
}
void loop(){
  Serial.println(analogRead(A5));
  delay(4000);
}

Thanks!

13

Well i do not know what i did but it seems as the sensor is not working. Thanks for helping me out

14

What value is the resistor?

If you remove the resistor from the circuit, the analog input should be pulled up to 5V so the analog input would return a value close to 1023. Does it?

Do you have use of a meter that can measure resistance?

15

All resistors work now i was just an idiot and forgot that with pressure sensors the value will be 0 once you throw in a resistor and apply no pressure. 10k 320 100k have all worked for me.