Engineered-By-Aaron - Arduino-Based Gauge Cluster

NA Mazda Miata Gauge Cluster, Disassembled

Arduino Gauge Cluster: I.D. Verification - Coming Soon!:

Overview

I've always appreciated a great gauge cluster in a car. I've had the privilege of experiencing some all-time greats in my motoring career, and it's become a personal focal point when experiencing a car's interior design.

These include the E60 (2004-2010 5 Series BMW)'s cluster, which I loved for it's warm backlight color, executive design and (with the help of a JB4 piggyback tuner,) could turn my 2010 535i's useless 'mpg' analog sweep into a boost gauge!

Other favorites from my automotive past include the 2021+ Acura Tlx Type-S and 2001 Toyota 4Runner, with lowlights mostly residing with VW's modern all-LCD approach, which I saw reflecting my own frustrated face more often than the info displayed! (PNW issues, the winter light gets so low that it pierces straight at dashboards.)

In stark contrast, I've been quite dissapointed with many offerings for automotive retrofit; while high-end offerings from Dakota Digital and the like are fabulous, the high cost scared me away. Vintage/analog options look out of place to my eye, and so I took to YouTube to see if some fellow junkyard enthusiasts had found a way to integrate some used parts into a custom solution.

I decided to start out with the choice every Miata owner has been yelling at their screen since the start of this article - "Miata is always the answer!" In the case of my 1961 Falcon project, I found that the compact size and cheap availability of interior parts made the Miata a great fit for my application. Also, the stock cluster of an NA Miata was surprisingly close in size to my stock unit!

For the sensible hot rodder, this can actually be all you need! Because Miata owners are so creative with engine swaps, there are guides galore which detail converting wiring harnesses from many modern engine platforms (Especially LS and K-series swaps!). However, I couldn't leave 'good enough' alone; for my application, I selected a broken unit from eBay; since I planned to replace the electronics immediately, a quick clean of the guage faces and needles was worth the savings.

If any Miata fans are still following this mess, here's where I likely lose you - although the size and layout of the Miata gauges are great for providing properly-sized needles and guage face templates, in my final implementation, this will be more of an Arduino-based HAL wearing the skin of a desecrated Miata cluster.

I began my mess by picking up supplies. These included a pair of pair of Arduino-based SBC's - one MEGA2560, and a new Uno. (These were selected only because of what I happened to have on-hand; no personal preference.) I also grabbed a pair of mismatched displays - one mono-color OLED and one circular watch-style LCD - and the motor controller units and servo motors used in this example from the Adafruit website. Since I chose to use leftovers from previous projects to keep costs down, my total bill of materials was about $30.

Oh boy, now it's time to code! Since I planned to use an MSD 6014 ignition box on my Falcon, I based the inputs of my software on the standard outputs I expected from my car's few systems:

- Rpm (Square-wave pwm pulse in my case, delivered via single wire from MSD box.)

- Fuel (Though my old fuel sender unit is already on the fritz, I'm anticipating an eventual swap of fuel pump and gas tank when I complete the engine swap, so I'll optimistically prepare for a standard voltage-based input here, to be refined later.)

- Speed (Plan is to use a Tremec gearbox, which luckily provide analog or digital speedo outputs. Woohoo!)

- Oil Pressure (My engine was rebuilt from a core which had been abandoned because of oil pressure issues... although I extracted some thoroughly thrashed camshaft, rod, and main bearings, I'd still like to keep a close eye on this.)

- Turn Signals, lights/high beams, and ignition inputs will all come from the 1961 Ford wiring - nothing tastier than the forbidden spaghetti of ancient wires and dust. Uck.

Next, I'll define my outputs. This is as customizable as your creativity and stubbornness will allow! In my case:

- Analog guages, based off the Miata's design, for RPM and Speed. I like the layout of this pair to be front-and-center, much like my old BMW, and the donor Miata cluster.

- Digital (Circular) - This will be center-top in my cluster, and serve as a general display for values which I find to be most helpful when exact values are visible. Air-Fuel Ratio is a great example here, as I will be using a dual-quad carboretor setup, and tuning those setups is not for the faint of heart. I think I will add a color-specific ring around the circumference of the display which can act as a visual aid for emergencies, like lean fuel mix, or high coolant temp.

- Digital (OLED) - This is a basic single-color white-on-black display, so I'll likely use this to display text explaining the state or units represented on the circular LCD.

- Analog Temp and Fuel gauges, on either side of the tach/speedo pair. This will mirror the layout on both the stock Falcon design, and the Miata cluster design.

Next step here is the circuit design. This is where my inadvertant choice of an arduino Mega comes into play - because I plan to use so many analog inputs, as well as lots of digital outputs (2 each for each servo for the analog gauges!), I felt grateful to have the typically-overkill selection.

I followed wiring designs from the aforementioned Adafruit example project, connecting all the outputs and displays to the Mega with the exception of the color LCD. Because I want to use LVGLs to animate a gauge for this display, I figured that the added compute from a newer-generation Arduino would be noticable in driving the whole (2-display, 4-servo, lots of inputs) system. I chose to solder the stepper motor controllers to some prototyping PCBs, as this allowed enough cable length to stretch standard wires from the central board to the outputs at the outskirts of the cluster, as well as organizing the nest of wires a bit less hectically.

It's now time to verify the wiring - using basic digitalWrite commands in Arduino code, give each output motor and display a little proof-of-life wiggle or flash! Also, this would be a smart time to confirm that the 2 boards can intercommunicate; coming soon!!!

Next steps will include scanning and digitally designing the gauge faces and housing, and designing the faces! Stay tuned for updates to come. In the meantime, enjoy these photos of my ol' BMW, which I named 'Astrid' after the character from Netflix's 'The Politician'; my Astrid was similarly tempermental to say the least, so I've included her tow highlights, as well as the aftermath of an icy day and an open differential... lots of footprints and tire marks in the snow!