Hello guys! Newbie in electronics here. (hope it's in the right place of the forum)
I'm trying to learn by myself with a brand new Uno, but I'm really afraid of trying wild new stuff and frying my new toy. :) The thing is, I used my Arduino to create a simple thermometer with a LM35 (http://pdf1.alldatasheet.com/datasheet-pdf/view/8866/NSC/LM35/+5757uIOzZKMAN+/datasheet.pdf) sensor. I simply hooked up everything according to a tutorial I saw like this: LM35 / | \ +5v A0 ground and everything worked perfectly, I got the correct voltage in A0 for room temperature in Celsius and everything. But then, I was looking at the datasheet and realized that below 0 degrees Celsius, LM35 would output an negative voltage. So, if I'd go below 0, would that damage the input pin (A0)? In the datasheet there's a circuit configuration that allows one to measure down to -55C (Figure 7). I'm still trying to understand that, but meanwhile, I came out with an alternate way of doing almost the same thing. I would like someone to confirm or explain to me why that wouldn't work. If I hook it up like this: LM35 / | \ D9 A0 D10
And then, I'd analogwrite 5v to output pin D9 and 1v to D10 (thus giving an difference in potential of 5-1=4v) so that when LM35 outputs a negative value (let's say, -1v) I would read it in A0 as 0v. Does that make sense or I'm way off course?