AVR-Chat

On Sat, 2005-10-22 at 01:30 -0700, pinky elodia wrote:
> i got a question, can i build multiple sensor using
> one microcontroller (ATmega128).thinking of using 2
> analog sensor. can i use 4 input adc for 4 sensor?

  Absolutely!  You have to keep the "gotcha's" in mind, however:

1)  the maximum update rate for the sensors (assuming that you read them
sequentially) is going to be 1/4 of the maximum update rate of the ADC
on the chip (because you are sharing the ADC between 4 inputs).

2)  the switching of the multiplexer can cause additional noise in your
readings, as well as prohibiting the use of the noise canceling sleep
mode (strictly speaking, you COULD still use it, but it would reduce the
maximum number of updates per second, as you would have to expend time
setting and iunsetting ther sleep mode between each update).

   If you don't need to update your sensor readings very often (say, if
10 or 100 (or possibly even 1000) readings per second per sensor is
adequate) then there should be no problems, even if you want to use the
noise cancelling mode.

   As always, someone who has more direct experience with this specific
issue is welcome and encouraged to correct me if I am mistaken.

Tom