Well, lets see…
ok, so the sensor throws between 0V and 12V, possibly an absolute max of 14.1V
so, if i use a voltage divider, most of the range (times .5) would give me a decent value, once it gets to about 12 V, the Voltage at the divide point will be around 6V, and can go as high as 7 with Battery+ Voltages from the alternator going as high as 14.1!
I want to take readings from various Auto sensors in a car and report on them via LCD or whatever, like Engine temp, Fuel level, Vacuum pressure, MAF sensor reading, MAP reading, RPM’s, blah blah blah
most of these sensors have 3 wires, one is GND, the other is +12V( or whatever voltage V+ is at), and the last is an analog value between the two. I want that analog value, and give it a meaning.
Say I measure the Engine coolant temp sensor voltage, I get 8.5V. I can get out a thermometer and measure the temp and get 175 Degrees, I know that when that sensor outputs 8.5V, the temp is about 175 degrees. so by measuring the voltages at different levels, I can almost calibrate the readings in this way. mind you on a vehicles electronics there isn’t much to say as far as precision is concerned…but approx values are ok for my cause.
My problem is that i have the sensor readings in analog values between 0v and 12/14V.
I need to Cap out the max at 12V, and bring the entire scale down to Arduino level…0V to 5V…
or do I?
can I use the Aref and connect it to B+ on the car and use the analog pins directly on the analig inputs? im almost sure I can’t…
some useful analog reference! sheesh!
With my electronics background, the only solution I can think of is to make a comparator that will Not Amplify, but the opposite of amplify or limit the Voltage range, but this has to be done on an analog level due to the sensor voltage readings. I was hoping I could use the Aref on the Arduino, but i can’t see how anyone has used the damn thing.
Thanks BTW, im still tryin to figure this shit out!