For those of you following my “Smart Gauge” stepper-motor gauge project, things have been moving right along. The firmware is nearly done, and the browser-based GUI is getting very close to done as well. The WiFi “access point” and web server are both working flawlessly. Everything is now working as I want, and the prototype gauges and senders have been working perfectly for months now. I think I finally have a solution to the last mechanical problem - coming up with a viable means of producing the new needles for the gauges, to fit the stepper motor movements. The answer is an SLA 3D printer!
I’ve made one major change in the architecture - I made the "smart gauges a bit dumber. But, with good reason. Initially, the gauges were pretty smart, largely self-contained - reading the sensors, scaling/correcting the readings, and controlling the stepper motor movements. The “system controller” tied all the gauges together, and provided the means of configuring the many lighting options, and providing a backup display to any WiFi connected smartphone, tablet, etc. But, this architecture created too many potential failure modes where a single failed gauge could impact other gauges. So, I went ahead and moved most of the smarts into the “system controller”, as it done on all modern cars, and pretty much made the gauges slaves, so failure of a single gauge cannot affect other gauges. This means that the three “smart gauges” don’t even have to be connected, and you can still watch your temperature, oil pressure and fuel level on your smartphone.
This also makes it easy to support redundant sensors for temperature and oil pressure, so even a sensor failure will not cause a loss of accurate readings.
I now only have to do the final revisions to the gauge PCBs, and do the (very simple) system controller PCB.
Here is the current GUI, as it will appear on a mobile phone screen:
First, the main page, which provides a “virtual dashboard” for the temperature, oil pressure and fuel gauges, as well as buttons to access the configuration and calibration pages.
This is the lighting configuration page:
And the Fuel Sender Calibration page, with a calibration in-progress:
More to come, before long…