Go Down

Topic: ADC cross-interference (Read 616 times) previous topic - next topic

xianwu

I'm using arduino mini pro. 4 ADC ( A0, A1, A2 A3, ) to convert LDR( light dependent resistor) voltage to digit.
The  circuit is like this  5v---5.6K--@--LDR----GND.   the measure( ADC) is at @ point. seems four converted value are interference each other.  the program read A0, A1, A2, A3 one by one.  if they have interference, how to solve it?

thanks
xianwu

CrossRoads

Read each Ax twice, use the 2nd reading. Gives the data time to settle.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

xianwu

thanks for your suggestion.
actually, I read each ADC 6 times, remove Max and Min then use the rest 4 for average. and between each read I have 10ms delay.

CrossRoads

All that and it's still corrupted? Wow.
Designing & building electrical circuits for over 25 years.  Screw Shield for Mega/Due/Uno,  Bobuino with ATMega1284P, & other '328P & '1284P creations & offerings at  my website.

MarkT

LDRs in the dark can have a very high impedance - the ADC needs a drive impedance
of 10k or less to perform to specification - perhaps the sensors need buffering before
the ADC?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Go Up