I needed a simple turn counter to made a coil for hand made generator. It was an idea in theme of green power contest. By the mean, what does mean green energetics: are they energy faculty graduates on theme of solar batteries; or it is energy drinks with green colourant? Oh, i think it is just DIY.
For this project I get almost minimal config. It is 16GPIO F030 with TM1637 for 7-segment LEDs. But when I connected to the first variant of board TLE49 hall sensor, leftover free ports wouldn't let me calm down. That is why I added some another functions (list below). I like compact minimal designs without unuserful functions, but even less I like unused ports.
* Clock on built in RTC (clocked by 8MHz system qrystal oscillator, F0 haven't got 32k OSC in).
* Pins for DS18B20 thermometer.
* Voltmeter 0-30V with LM324 op amp buffer.
* Yet another way to measure turns with TL331 comparator and IR LED/phototransistor pair
* Monostable multivibrator on TLC555 timer to measure RPM of petro