How to build a Dyno for micro RC

3D printed parts: Download here

PCB file: Download here. This is a Gerber file with .zip extension.

MCU: ATTiny85

Display: LCD 0.91" 128x32

Bearing: 2x5x2.5

Shaft diamter: 2mm

Arduino code:

/*
 * @copyright The H Lab
 * Board ATtiny25/45/85 (no Optiboot)
 * Chip: Attiny85
 * Clock: 8Mhz internal
 * OS: ATTinyCore
 * File -> Preferences (Addition Boards Manager URLs) http://drazzy.com/package_drazzy.com_index.json
 */

#include <Tiny4kOLED.h>
#include <TimerOne.h>
#include <PinChangeInterrupt.h>

int count = 0;
int speeds = 0;

int testPin = 1;

void testLed(){
  digitalWrite(testPin, HIGH);
  delay(100);
  digitalWrite(testPin, LOW);
  delay(50);
}

void setup() {
  pinMode(testPin, OUTPUT);
  testLed();
  
  // Send the initialization sequence to the oled. This leaves the display turned off
  oled.begin();
  
  // Clear the memory before turning on the display
  oled.clear();
  
  // Turn on the display
  oled.on();
  
  oled.switchRenderFrame();
  
  // interrupt
  attachPCINT(4, triggerFunc, FALLING);
  Timer1.initialize(250000); // 0.25s
  Timer1.attachInterrupt(calcSpeed);
  
  testLed();
}

void calcSpeed() {
  detachPCINT(4);
  speeds = count * 80; // x4 (=1 s because count in 0.25s). Then x60 for 1 minute. Finally /3 interrupt per round => 80
  count = 0;
  attachPCINT(4, triggerFunc, FALLING);
}

void triggerFunc(){
  count++;
}

void showSignature() {
  oled.setFont(FONT8X16);
  oled.setCursor(36, 2);
  oled.print(F("The H Lab"));
}

void loop() {
  oled.clear();

  showSignature();
  
  oled.setFont(FONT6X8);
  oled.setCursor(40, 0);
  
  String strSpeed = "";
  strSpeed.concat(speeds);
  strSpeed.concat(F(" rpm"));
  oled.print(strSpeed);
  
  oled.switchFrame();
  
  delay(100);
}