Strange ADC behaviour
Posted: 16 Nov 2017 10:04
I have a simple set up. A3 channel of ADC is connected to ACS712 current sensor through voltage divider (to get maximum 3v instead of 5v).
No current is applied to ACS712 so it constantly outputs 1.5v. Other channels are not connected to anything.
I collect values to see them on plotter
Resulting picture:
a0 blue
a1 red
a2 green
a3 yellow
I can not get:
1. Why A0 and A3 charts has quarter of the range spikes
2. Why levels of not connected channels are so different
2. Why a1 and a2 noise is so correlated
No current is applied to ACS712 so it constantly outputs 1.5v. Other channels are not connected to anything.
I collect values to see them on plotter
Code: Select all
* int a0= analogRead(A0);
int a1= analogRead(A1);
int a2= analogRead(A2);
int a3= analogRead(A3);
Serial.print(a0);
Serial.print(" ");
Serial.print (a1);
Serial.print(" ");
Serial.print (a2);
Serial.print(" ");
Serial.print(a3);
Serial.println();
a0 blue
a1 red
a2 green
a3 yellow
I can not get:
1. Why A0 and A3 charts has quarter of the range spikes
2. Why levels of not connected channels are so different
2. Why a1 and a2 noise is so correlated