PSI - Issue 64

M. Komary et al. / Procedia Structural Integrity 64 (2024) 693–699 Mahyad Komary/ Structural Integrity Procedia 00 (2019) 000 – 000

695

3

2.3. Digital Temperature and Humidity Sensor (DHT22) The DHT22 sensor, made by Kuongshun Electronic (China), measures temperature and humidity using a capacitive humidity sensor and a thermistor, providing calibrated digital output. Variations in humidity and temperature affect the speed of sound, which is necessary to measure the distance using the ultrasonic sensor. Figure 3 displays the sensor's schematic.

Fig. 3. Schematic of DHT22 sensor.

2.4. Time-of-Flight Laser-Ranging Module (VL53L1X) The VL53L1X, produced by STMICROELECTRONICS (China), is the quickest small ToF sensor available on the market, offering precise ranging up to 4 m and fast ranging frequency up to 50 Hz. It combines a 940 nm invisible Class1 laser emitter, physical infrared filters, optics, and a SPAD receiving array into a small reflowable module to offer optimal ranging performance under various ambient lighting situations. The VL53L1X uses ST's latest version of ToF technology, which enables precise distance measuring regardless of the target's color and reflectance [7]. Figure 4 shows the schematic of this sensor.

Fig. 4. Schematic of VL53L1X sensor.

2.5. Motion Tracking Device (MPU-9250) The MPU-9250, the smallest 9-axis motion-tracking device in the world, integrates a 3-axis accelerometer, gyroscope, and magnetometer to provide comprehensive motion tracking and orientation data. It uses the most recent design breakthroughs from TDK InvenSense (China), which allow for significantly smaller chips and lower power consumption without sacrificing functionality or affordability. The MPU-9250 is a System in Package (SiP) that integrates two chips: the AK8963 3-axis digital compass and the MPU-6500, which has an onboard Digital Motion ProcessorTM (DMPTM) that can process complex MotionFusion algorithms [8]. Figure 5 shows the schematic of this sensor.

Fig. 5. Schematic of the accelerometer sensor MPU9250.

3. Communication with NodeMCU Some sensors employ the inter-integrated circuit (I2C) protocol, whereas many sensors use digital and analog interfaces to upload the measured data to the microcontroller. With the help of this protocol, one or more "master" chips (NodeMCU) can connect with several "slave" digital integrated circuits (Sensors). similar to the Serial Peripheral Interface (SPI), which is meant exclusively for internal, short-range communications between one device and another. The digital ports of the NodeMCU are connected to the ultrasonic sensor and DHT22. It was necessary to link the