With the development of the times, microcontrollers have become one of the essential learning topics for many electronic engineers. However, learning microcontrollers is not easy. If you master the following eight knowledge points or techniques, learning microcontrollers will be much more efficient!
1. Choosing Pull-Up ResistorsIn microcontroller circuits, the choice of pull-up resistors is very important as it can enhance the driving capability and stability of the circuit, while also protecting the internal circuit from external interference. Choosing the appropriate pull-up resistor requires consideration of the following factors: ① Resistance value: The resistance value of the pull-up resistor should be selected based on the circuit’s impedance and driving capability requirements. Typically, the resistance value ranges from 1K to 100K. ② Power supply voltage: The resistance value of the pull-up resistor needs to be compatible with the power supply voltage to ensure the stability and reliability of the circuit. ③ Driving capability: The pull-up resistor needs to have sufficient driving capability to drive larger loads.
2. Calculating Series Resistors for LEDsMicrocontrollers typically use LEDs as output indicators, and the role of the series resistor for LEDs is to limit the current and protect the LED from burning out. The calculation method for the series resistor is as follows: ① Determine the working voltage and current of the LED. Typically, the working voltage of the LED is around 5V, and the working current is around 20mA. ② Based on the power supply voltage and the LED’s working voltage, calculate the resistance value of the series resistor. The calculation formula is: (Power Supply Voltage – LED Working Voltage) / LED Working Current. ③ Choose an appropriate series resistor for connection.
3. Insufficient PortsIt is common to encounter the problem of insufficient ports in microcontrollers, which can be resolved by the following methods: ① Utilize the internal resources of the microcontroller: There are typically some available ports within the microcontroller, such as PWM, UART, etc. These ports can be used to expand external devices. ② Use chip expanders: Some chip expanders, such as I2C, SPI, etc., can be used to connect external device ports to the expander and then connect to the microcontroller through the expander. ③ Use multifunction port expansion chips: These chips integrate multiple ports internally, making it easy to expand the number of external device ports.
4. Filtering CapacitorsFiltering capacitors in microcontrollers serve to remove power supply noise and interference, ensuring stable operation. Factors for selecting filtering capacitors include: ① Capacitance: The capacitance of the filtering capacitor should be selected based on the frequency of power supply noise and the power consumption of the microcontroller. Typically, the capacitance ranges from 0.1uF to 1uF. ② Voltage rating: The voltage rating of the filtering capacitor should be higher than the power supply voltage to ensure the capacitor will not be damaged due to overvoltage. ③ Installation position: The filtering capacitor should be installed near the power input to maximize the removal of power supply noise.
5. The Role of TransistorsTransistors in microcontroller circuits serve to amplify current and voltage signals, implement logic gates, and can even act as switches to control the circuit’s on and off. The selection of transistors should consider: ① Type: There are two types of transistors, NPN and PNP, which should be selected based on the circuit’s requirements. ② Voltage rating: The voltage rating of the transistor should be higher than the power supply voltage to ensure the transistor will not be damaged due to overvoltage.
6. Seven-Segment DisplaysSeven-segment displays are display devices used in microcontroller applications that can display numbers or letters in LED form. The selection of seven-segment displays should consider: ① Number of display digits: The number of display digits for the seven-segment display should be selected based on actual needs, commonly 4 digits, 8 digits, and 16 digits, etc. ② Display color: The display color of the seven-segment display can be selected based on actual needs, commonly red, green, and blue, etc. ③ Driving method: There are various driving methods for seven-segment displays, such as static driving and dynamic driving, which should be selected based on actual needs.
7. Key Bounce and EliminationFor microcontrollers, key bounce is a common issue caused by mechanical and electrical noise generated during the pressing and releasing of keys. To eliminate key bounce, the following methods can be used: ① Software debouncing: Use software algorithms to filter key inputs and remove noise interference. ② Hardware debouncing: Use hardware circuits to filter key inputs, such as using RC filter circuits, etc. ③ Dual debouncing: Use both software and hardware methods for debouncing to improve system stability and reliability.
8. Pull-Up and Pull-Down ResistorsThe role of pull-up resistors is to pull the pin high, ensuring that the pin is in a high state when not connected; the role of pull-down resistors is to pull the pin low, ensuring that the pin is in a low state when not connected. The selection of pull-up and pull-down resistors should consider: ① Resistance value: The resistance value of pull-up and pull-down resistors should be selected based on actual needs, commonly 1K, 10K, 100K, etc. ② Power supply voltage: The resistance value of pull-up and pull-down resistors should be compatible with the power supply voltage to ensure the stability and reliability of the circuit. ③ Driving capability: Pull-up and pull-down resistors need to have sufficient driving capability to drive larger loads.