1. Optional IR speed: Optocoupler module for detecting the slotted optical speed measuring sensor with infrared. The slit photograph consists of an infrared lightemitting diode and an NPN phototransistor with a gap width of 5.9 mm. As long as the nontransparent object passes the slot type, it can be activated (used with the store encoder wheel) to produce a low TTL level. 2. Technical data: Operating voltage: 3.3 V 5 V. Output format: digital switching output (0 and 1). When VCC and GND are connected, the signal indicator of the module lights up. When freezing, the OUT output is low and the signal indicator is off. The OUT module can be connected to the relay to form a limit switch and other functions, and can also be connected to the active buzzer module to form an alarm. 3. Programming: The OUT output interface can be directly connected to the IO port of the MCU. Normally connected to an external interrupt to detect if the sensor has occlusion. For example, the encoder wheel of the motor can detect the engine speed. The OUT port of the speed measuring module is connected to the external interrupt port of the MCU. Whenever infrared rays are directed, it is an external buffer. 4. Measurement Measurement distance: the output of the speed sensor is a pulse signal, a pulse is interrupted once; the infrared beam is weak when activated, so we set the interrupt to the lowlevel touch mode. SPEED MEASUREMENT: According to the idea of distance measurement, we use MCU timer to calculate the number of external interrupts received in one second.