Quote:
Originally Posted by miro
In a recent IEEE Spectrum magazine article about using Arduino for tracking fuel economy, the author is using an analog guage located in his centre console.
I've often wondered about using an analog guage rather than a digital display.
On my 2012 Matrix all the guages are analog and it seems to me that maybe there's a reason for that - dunno.
miro
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Define "analog".
If it's a 2012, the gauges are digitally driven even if they have physical needles. The only difference is that the digital output is used to drive a stepper motor or something similar to move that physical needle instead of just outputting to a LCD. So yes, the same could be applied to any digital gauge, including from an Arduino or other similar device.
Take the digital signal, process that to see how much a stepper motor with a needle attached should turn, or you could output a PWM signal push that through a coil in an ammeter to move the gauge. An Arduino should have everything you need to do that on it already.
The only reason for having "analog" gauges in a modern car is for the look. Everything is processed digitally, and the digital output has to be converted into the mechanical movement of the needles.
Back in the old days gauges were analog because there weren't any digital signals to go off of. Speedometers had a spinning magnent that pulled on a metal disc hooked up to a spring. The faster the magnent would spin, the more it would pull on the disc that was next to it. Nearly all other gauges would move due to how much current was passing through them. They were essencially all ammeters. A fuel level sending unit was nothing more than a poteniometer that sent an analog voltage signal to the gauge. The voltage had to pass through a resistor, and since current equals voltage divided by the resistance, you'd get a specific current passing through the gauge for specific voltage that was being sent to it. Temp gauges worked by using a thermister, a resistor that changed resistance due to changes in heat.
But fastforward to today and everything is digital. The fuel level, engine temp, etc is converted into ones and zeros, aka "a digital signal." That is fed into the ECU for all it's digital needs and for sending to any dash gauges, whether they are LCD or mechanical.