smart car

Function introduction;
currently available functions;
infrared tracking, ultrasonic ranging, lighting, able to detect dark environments and turn on lights, Bluetooth remote control, turning
design drawing: ![0a197cbf5ef705467e742fa1daabb6d.png] ![Screenshot 2023-07-01 145856 .png] The infrared tracking circuit is based on the ITR9909 sensor as the core, using the LM393 comparator to detect the input status, and with the potentiometer for precision adjustment, the measurement distance is adjustable within the range of 1mm~15mm.
Car tracking generally involves walking along a black line on a white floor, using the reflection of infrared light in different colors for identification. Infrared light is always emitted to the outside. If the bottom of the car is a white floor, the light will be refracted back. At this time, the receiving tube receives the signal and outputs a low level through the comparator. The LED indicator lights up and the microcontroller detects the low level; if the car is driving on Around the black line, the infrared light is absorbed by the black color, and the receiving tube cannot receive the emitted signal. At this time, the comparator circuit output is high level, the LED indicator light goes out, and the microcontroller detects the high level. Tracing is actually a process of finding black lines and walking along them
! [Screenshot 2023-07-01 150421.png] LED drive circuit;
a car without lights has no soul, so you must choose to highlight The LEDs are used to simulate the left and right lights of the car. The cathode of the LED lamp is connected to the power supply ground GND. The value of the current limiting resistor here is slightly smaller, making the LED current larger and the lamp brighter. The program control of LED lights is also relatively easy. The left end of the R23 resistor is connected to an LED-R network tag and the microcontroller pin. When the pin outputs a high level, the diode conducts and the LED lights up. By using the timer, delay and IO port output configuration, you can achieve the effects of flashing car lights and high and low brightness.
![Screenshot 2023-07-01 151950.png] ADC sampling circuit:
ADC is the abbreviation of analog-to-digital converter (or AD converter). ADC is a device that converts analog quantities into digital quantities. A common application is to convert continuously changing voltage values ​​into digital quantities. The principle is the sampling principle, which can be simply understood as sampling the voltage value at a certain frequency so that the continuous value becomes a discrete value, and a number of digital quantities are obtained.
![Screenshot 2023-07-01 152218.png] Ultrasonic module
The model of the ultrasonic module is HY-SRF05. It uses five pins to connect to the microcontroller, which are GND, OUT, VCC, Trig and Echo pins. Except for the power pin Feet, only two signal lines are needed to detect the distance of ultrasonic detection of obstacles in front. Compatible with four-legged HC-SR04. ![WeChat picture_20230701152947.png] Bluetooth module
Since we are building a smart car, wireless control is indispensable. Commonly used smart car control solutions include infrared, Bluetooth, WIFI, 2/4G and other solutions. This car uses Bluetooth control. This method has a simple circuit. The mobile phone is the remote control. In addition, you can also learn the design of Bluetooth APP.
The smart car uses the HC05 Bluetooth master-slave module, which has a total of 6 pins. The EN pin is used to control the Bluetooth module to enter the AT command. When set to high level, the status and data transmission of the Bluetooth module can be set; the VCC pin and the GND pin are power input pins, and the input voltage range is 3.6-6V; TXD and RXD are the serial port pins used to connect to the microcontroller. RXD is connected to the TXD of the microcontroller, and TXD is connected to the RXD pin of the microcontroller. Please note that it cannot be connected in reverse; the last pin is the STATE pin, and its function is to display Bluetooth pairing. status. When Bluetooth is connected to the mobile phone, this pin outputs high level.
Photosensitive:
Since it is a smart car, it also needs to have a function of automatically turning on the lights. By using a photoresistor to control the corresponding output signal and using an integrated operational amplifier to amplify it, the amplification effect is achieved
! [5f3b35e16d400f4a4ec8be3813adad0.png] Voltage reduction:
Using voltage reduction voltage to provide a stable 5V voltage to the chip so that it can operate normally.
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