Problem with analog ports reading

Projects General Guidance
1

Hey guys, so I have some doubts on a project i'm working on now. I'm using Arduino Pro Mini (Chinese version) and I've created a program that will send data from external sensors connectd to the analog ports on the Arduino to another program in LabVIEW. I connected a potentiometer to the A2 pin and a temperature sensor LM35 to the A3 pin. The program runs ok when I use two potentiometers, one instead of the LM35 sensor, but something happens when I use the LM35: everytime I vary the potentiometer, the LM35 changes as well and that is not what I desire, as you might have already guessed. It confuses me given the fact that they are wired to two different analog ports. I decided to use the analogRead example program for mere testing purposes and the same issue happens. I don't really know what a viable solution or explanation might be. I will be very thankful if any of you could give me a hand on this!

The first image shows the readings from port A2 and A3, when the potentiometer (A2) is at its lowest value (0). The second one shows the readings when the potentiometer is at its highest value (1023~) and the last image shows an intermediate value on the potentiometer. As you can see, the values sent from the LM35 sensor (A3) vary widely when the values from the pot are changed. On these measurements the LM35 sensor remained untouched so that it would keep the same temperature.
schematics of the connection:

sch.png
sch.png1021×622 54.1 KB

Screenshot_1.png
Screenshot_1.png1919×1079 131 KB

Screenshot_2.png
Screenshot_2.png1919×1079 132 KB

Screenshot_3.png
Screenshot_3.png1919×1079 132 KB

sch.png
sch.png1021×622 54.1 KB

2

Please provide a schematic that shows how you have the LM35 and the potentiometer wired up. You should attach and embed the image following these instructions:
http://forum.arduino.cc/index.php?topic=364156

3

Try reading each analogue input twice.
The second reading is likely free from the cross-talk you're experiencing.

int sensorVaue = analogRead(A2); // dummy read
int sensorVaue = analogRead(A2); // real one
int sensorValue1 = analogRead(A3); // dummy read
int sensorValue1 = analogRead(A3); // real one

Leo..

4

Wawa:
Try reading each analogue input twice.
The second reading is likely free from the cross-talk you're experiencing.

int sensorVaue = analogRead(A2); // dummy read

int sensorVaue = analogRead(A2); // real one
int sensorValue1 = analogRead(A3); // dummy read
int sensorValue1 = analogRead(A3); // real one



Leo..

Thanks it seems to work just fine with this!