MPG Display - analog
 

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

My version of MPGuino supports analog output of either fuel remaining or fuel consumed, via a PWM signal.

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.

Analog guages are more perceptible.

Maybe. I have both a digital and "analog" speedometer in the Avalon, but I prefer to go by the digital readout. I think the problem with modern day analog speedometers is they want to put some ludicrous maximum speed on them, like 160mph or more, that I'd never do. So they have to cancel out a lot of smaller numbers, now jumping by 20's (0 l | l 20 l | l 40 l | l 60 l | l 80 l | l 100 l | l 120 l | l 140 l | l 160). It makes it hard for me to see what speed I'm actually going, so I use the digital display instead.

The only downside is that when I downshift the LCD changes from whatever I have set there (such as the digital speedometer) to a tachometer, which makes me have to look over at the analog speedometer and try to figure out what speed I'm going at.

If they'd just set the maximum speed on the speedometer at the maximum legal speed limit (85mph in the USA) then it would be easier to see and understand what speed I'm going.

The unrealized advantage of digital is the heads-up display.

No reason why they couldn't provide driving glasses with a Bluetooth connection and Augmented Reality.

Not just the read-outs, make the whole roof of the car invisible with an 'omnidirectional rear-view mirror'.

They did that for a short time in the 80s on imported motorcycles. I find this incredibly annoying. I agree with the point, just not the proposed number. I only find it annoying because I am speeding, but not knowing how fast I am going isn't that great either.

90 or 95?

When the entire town has a 25mph speed limit, the car is automatic so full acceleration is always at the tip of the foot (maybe it's time to install a block behind the accelerator) but the speedometer barely moves when I go 25mph or under, that is irritating.

One thing that I'd like to see on modern cars with their fancy smancy LCD (or OLED, NanoLED, etc.) displays would be customizable gauges. Just let us adjust them how we see fit. I never hit anything over 65mph, so let me set max to 65mph if I want. With the way technology is today it should be possible. But no! We can't have people customizing their cars these days now can we!

It used to be possible to customize your gauges without making it look like a frankenstein hack job.

https://encrypted-tbn0.gstatic.com/i...EyZ7Y&usqp=CAU

https://live.staticflickr.com/6/7618...d387da62_b.jpg

https://www.thesamba.com/vw/gallery/pix/447033.jpg
www.thesamba.com/vw/gallery/pix/447033.jpg
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That looks like almost exactly how I had my '72 Super Beetle dash configured, with AFR gauge and all.

No 140MPH speedo though.

I understand that today the signal processing in cars is all digital.
But the displays can be an analog meter.

The article I quoted uses an analog meter to display that goes from 0 to 10 and he programmed his system to calibrate it so it is the MPG value divided by 10.

So, the pointer on 3 on the display means 30 MPG.

Seems to me that once you get used to the quirks of your own driving, it only takes a quick glance at the analog display to understand what your result is.
A digital value like 31.7 MPG probably distracts you because your brain wants to interpret the numbers.

I find that I look at the (analog) tachometer more than the (analog) speedometer, because I know the relationship ( engine speed vs vehicle speed) very well, even though the signal processing is digital .

And in any case I don't think the difference between, say 31.7 MPG and 33.4 MPG on a digital display, in most driving circumstance will mean all that much.

When specifically testing - that's a whole different driving scenario.

I like the idea of gauges with simple 1, 2, 3, 4, 5, etc. numbering. Even 10, 20, 30, 40, etc. is fine to me. It's the gauges that use 5's (5, 15, 25, 35) or that skip numbers (20, 40, 60, 80) that are hard for me to read and understand, unless the needle is exactly on that number. But when it's on the line between 40 and 60, I will think I'm going 45mph in stead of 50mph.

I don't mind that fuel mileage is displayed digitally, although I find it quite meaningly to see instant fuel mileage, digital or analog. I'd rather see the average fuel mileage, in which case having a decimal is nice.