Analog Pin input problem with my macbook pro.

Hi. All. I am having a problem with reading analog signal through analog pins to my macbook pro.

I have a Mega 2560 and a third part duelmilano. I tested both on a windows machine of reading sensor voltage from analog pins. Input voltage is around 2v - 3v.

But if I use my macbook pro (Lion system 10. 7.4). Every time I connected the sensor output to an analog input. The voltage jumps to more than 5 v straight away.

Is that something wrong with the driver?? Because with the same codes, everything works fine on my pc desktop. But unfortunately, I have to use my laptop with arduino because of other software reason. And both of my arduino boards are having the exact same problem.

I use the latest version FTDI driver for 64bit MAC OS: version 2.2.17

Many thanks to you all



When using on Macbook Pro. I tested some examples using digital pins. They work fine. Analog pin works fine as well with the potentiometer example.

But my sensor is powered by +/9 v and output a rectified signal with the voltage range between 2-3v.

Thanks again

I just notice one thing. When I use the sensor with arduino and connect on PC. Things are fine. I am reading nice voltage result from the serial monitor. But as long as I touch my macbook pro. The voltage jumps straight to maximum 1023.

And I am always feeling numb or even electrocuted by the macbook pro. Is that the reason why I cant use the analog pin on the macbook pro. Because there are electric current on the laptop surface which interferes the analog pin.

It is a guess as I dont have much electronic background.


And I am always feeling numb or even electrocuted by the macbook pro.

That’s a bit worrying. I’d get it looked over, if it was me.

Yes you are right. I should get it checked. Now I am confirmed where is the problem. If I am using it without the power supply of my laptop. Everything works fine. Once I plugged in the power supply. The input voltage jumps up.

Which is the same as the electrocute problem, it only happens when the power cable is connected. I checked on the internet before and found many people having the same problem which they feel numb using macbook pro. Now I really need to have it check.

Never heard of this problem that “many people” are having. Sounds like a missing or bad ground connection somewhere.

By the way, you can only get electrocuted once.