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I currently have an Arduino Uno, as you all know the atmega328 chip has more then 5 ADC ports however the uno only provides the ability to use 5 A0-A4. i need input from 7 IR sensors "monday to sunday".

Can i use the digital ports to input an analogue inputs (i know you can do the reverse which is use analog as extra digital ports), or will i have to use a standalone ADC before giving the signal to the digital port?

thanks
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You cannot use a digital port as an analog in.
The analog inputs are acutally a 6:1 multiplexer to an ADC.

As KE7GKP suggested an additional external multiplexer such as the 4051 would be a good option. With this setup you will have 8 analog ins connected to a single analog pin on the Arduino. But you will need 3 pins to select the input channel.
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Another option is to use I2C devices uses analog pin 4 and 5, you can connect over 100 I2C devices to your Arduino ...
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Rob Tillaart

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That multiplexer will do the trick perfectly, thanks for the help.
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Quote
i need input from 7 IR sensors "monday to sunday".

Seems to me most "IR sensors" use digital pins rather then analog. What kind of IR sensors are you using?

Lefty

 
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