Compared with wired remote control, wireless remote control is not affected by distance, completely eliminating the hidden trouble caused by the towing cable remote control device, and bringing more convenience to people's daily work and life. With the rapid development of digital processing technology, wireless digital communication technology is becoming more and more mature. Its advantages such as strong anti-interference ability and easy processing of digital signals have gradually improved the anti-interference performance of wireless remote control systems and greatly improved safety performance. At present, the main fields of wireless remote control include ultrasonic remote control, infrared remote control and radio remote control. Compared with ultrasonic remote control and infrared remote control, radio remote control uses radio signals to propagate in the air and controls remotely according to the frequency of radio waves. It can penetrate certain obstacles and has a long transmission distance. Therefore, it has become the first choice in the field of wireless remote control and is increasingly used in the fields of national defense, military, scientific research and daily work and life.
The wireless remote control multi-way switch system with a frequency of 433.92 MHz is designed and manufactured using the wireless transmitter chip Si4010, wireless receiver chip Si4313 and C8051F920 microcontroller developed by Silicon Laboratories. It has a simple structure, stable performance, and easy control. It is suitable for occasions with more controlled electrical appliances and can realize multi-way and multi-functional control.
1 System Working Principle
The radio remote control multi-way switch system consists of two parts: radio transmission circuit and radio receiving control circuit. The system composition block diagram is shown in Figure 1.
Figure 1 System composition block diagram
The working principle of the switch system is to first input the bit number of the required control switch circuit through the key circuit, and start the instruction encoding circuit at the same time. The instruction encoding circuit generates a coded pulse signal with address coding information and switch status information under the control of the internal circuit. The pulse signal modulates the carrier signal, and the modulated carrier signal is amplified and tuned and transmitted by the RF transmitting circuit. After the radio receiving circuit receives the carrier modulation signal, the demodulation and decoding circuit demodulates the carrier modulation signal to obtain a coded pulse signal, and then confirms the coded address to confirm whether it is the address of this remote control switch system. If the received signal address code is the same as the local address code, the coded pulse signal is decoded and the data is output, and the corresponding switch circuit action is controlled by the single-chip microcomputer circuit. Otherwise, no decoding is performed, the single-chip microcomputer control circuit does not respond, and the switch circuit does not take any action.
2 Hardware Introduction
2.1 Introduction to Si4010
Silicon Laboratories' Si4010 RF transmitter is a single-chip remote control IC that only requires an external bypass capacitor, a printed circuit board, a battery, and a housing with buttons to form a complete radio remote control. It uses a patented high-reliability crystal-free oscillator architecture, which does not require an external clock source and is not affected by shock and vibration. Its carrier frequency accuracy is ±150 ppm in the commercial temperature range and ±250 ppm in the industrial temperature range. Its accuracy is twice that of traditional (SAW) transmitters and does not require an external crystal oscillator. It has automatic antenna tuning, which maximizes the transmission distance, provides stable output power, and effectively reduces adverse effects on the remote control. It contains an embedded 8051-compatible microcontroller with 1 4 kB RAM, 1 8 kB one-time programming (OTP) non-volatile memory, 1 128-bit EEPROM and 12 kB ROM for library functions. The digital peripheral functions on the microcontroller include touch wake-up GPIO, 1 patented 20-bit EEPROM with a read-write life of 1 million times, 1 LED driver, 1 sleep timer, 1 debugger, and 1 high-speed 128-bit Advanced Encryption Standard (AES) accelerator that can provide a secure unidirectional link. The operating voltage range of Si4010 is 1.8 to 3.6 V, providing ultra-low current consumption (less than 10nA standby current and less than 20 mA peak current) and low-power touch wake-up mode. It supports FSK and OOK modulation modes, supports PCB loop antenna, and has an operating frequency band of 27 to 960 MHz. The chip also contains LDO, temperature sensor, and low voltage detection alarm.
2.2 Si4313 Introduction
Silicon Laboratories' Si4313 chip is a single-ended general-purpose ISM band receiver with an operating frequency of 240 to 960 MHz, a programmable receiving frequency bandwidth of 2.6 to 260 kHz, a receiving sensitivity of -118 dBm, a data rate of 0.2 to 128 kb/s, FSK, GFSK and OOK modulation schemes, support for frequency modulation, single capacitor tuning network, support for PCB loop antenna, operating power supply voltage of 1.8 to 3.6 V, and ultra-low power consumption, high flexibility and low shutdown mode. Internal functions include: wake-up timer, automatic frequency calibration, front-end code detection, radio signal strength detection, integrated voltage regulator, on-chip oscillator, 64 kB FIFO, etc. [page]