Automotive gauges for HW monitoring

Hello stranger. If you are not sure what it is, you probably don't need this repo.

The software side of the project for converting cheap aliexpress gauges (RPM and Oil pressure in my case) to CPU and Memory indicators.

Software

This package has only a software part with a simple tray application that allows choosing between ports and refresh rates. Build supports only darwin+cgo.

Build

Just run make Gauges.app and check the out folder.

Communication

The COBS protocol is used for communication between PC and Arduino via serial port at 115200 baud rate.

There are two types of messages (before COBS encoding) indicated by the first byte:

1. Handshake: 0x01 to start the device.
2. Metric: 0x00 0xMM 0xCC where:
   • 0xMM is memory usage in percents rounded to uint8
   • 0xCC is CPU usage in percents rounded to uint8

Not sure if it's a bug in the used Arduino library, or I misinterpreted the COBS protocol, but another 0x00 is required at the end to let the microcontroller properly delimit the messages between itself.

Hardware

There is no simple approach. Everything should be custom-wired. I utilized 52mm ones from DynoRacing, connected them to Arduino Nano via PWM output, calibrated, and it was ready to go. Additionally, the photoresistor was added to regulate backlight brightness, especially at night.

The linear calibration ax+b=y could work, but I was able to achieve good results with a polynomial curve fitting.