Introduction - If you have any usage issues, please Google them yourself
Use C8051F020 system board, design a speed measurement instruments. The use of reflective photoelectric sensors designed to measure the system, the speed measurement. When the sensor aligned fan, the blades on white reflective, black non-reflective, the use of this principle, the speed measurement. And the speed value displayed on the LCD, to ensure that the error in less than 1Hz.