Hi all, I've been working with the idea of building a tachometer to be fitted on my older Kubota tractor. I've set up several different versions based on projects found on the web, each with a caveat or two, so I'm seeking some input from anyone who has experience.
The first one worked fairly well using an IR transmitter/receiver through a Schmitt trigger to Uno's interrupt for counting and displayed on a 16X2 LCD display. From there I moved to using a .96" OLED display. That worked fairly well, but to be honest my old eyes would never see it from the seat of the tractor to the dash, I needed something bigger. And I'd like to incorporate a "retro" gauge look.
So now I'm playing with 2.4" tft displays and just beginning to understand their operation, with new issues there. For example. A parallel interfaced shield such as mcufriend's works well for experimentation, but uses up most of the gpio pins including the interrupt, plus the logic level translation issues. But it is one of the fastest display options. But I still need a display that will give me access to an interrupt. So then I moved to an SPI interface 2.4" display, that leaves only the issue of level translation. BUT the display transitions are much slower causing flicker.
Next I started fooling with connecting the display to an ESP 8266, using examples in the TFT_eSPI library. This produces a very fast display transition, In part by the speed of the ESP8266 and the well written examples in the library. But so far I have not seen an example of a Tachometer using an ESP 8266, and have read in some threads that the inherent calls to the wifi functions can/will disrupt the program flow times, giving inaccurate readings.
So I guess what I'm asking for is opinions as to what might be the best set up for using a SPI interfaced display for use as a tachometer. I'd love to hear opinions.