Reading 0 to 100mV On Arduino Uno

Question

I have a project that I need some help with...

We have a signal that ranges from 0 to about 100mV. We need to translate that to a tone that gets louder as the voltage goes up.

I have an Arduino Uno board and have written a quick Scratch program (using ScratchX) that reads A0 and set's the volume of a tone based on that value.

But, I think that this will only work for 0 to 5V signals.

Is there a way to increase the sensitivity of the analog inputs?

Thanks in advance!!

Greg

rachaelp · Accepted Answer

The ADC on the Arduino is either 10-bit or 12-bit depending on the model. That means that your read value is in integer between 0 and 1023 for the 10-bit ones and 0 and 4095 for the 12-bit ones. So you can look at what range your are seeing from the read of the ADC and scale it to a range which works for what you are doing. So depending on what you are doing in your code it might just be a case of using an appropriate range for the values you are reading or you can use map() to make them more convenient for what you are doing.

rachaelp · Answer

Hi Greg,

The map() function should scale the input range for you. See here: https://www.arduino.cc/en/Reference/Map

Bear in mind that with a 0-100mV signal you'll have limited resolution and your steps will be large. A better solution is to scale the signal with an amplifier external to the Arduino so that it becomes a 0-5V signal into the ADC to make the best of the resolution of the ADC.

Best Regards,

Rachael

Reading 0 to 100mV On Arduino Uno

Top Replies