CN104935352A - A receiving device for wireless teaching - Google Patents

Abstract

The invention discloses a receiving device for wireless teaching, which comprises a singlechip, and a digital FM radio module, an LED display and key control module and a power switch module which are respectively connected with the singlechip, wherein the singlechip and the digital FM radio module are communicated through an I2C serial data bus interface, the LED display and key control module sends the change of key trigger level to the singlechip, and the singlechip sends corresponding instructions accordingly. The receiving device has the advantages of simplified functions, smaller volume, portability and lower cost.

Description

A receiving device for wireless teaching

technical field

The invention relates to the field of wireless access to electronic information communication, in particular to a receiving device for wireless teaching.

Background technique

Some workshops and factories have cooperative relations with colleges and universities to become the practice bases of colleges and universities. Under normal operating conditions, the practice base will inevitably produce large decibel operating noises. For the students and team guides who go to visit the practice, this large decibel noise seriously affects the normal teaching work, and it is difficult to achieve the best teaching effect.

In order to reduce the interference of noise to teaching work, the existing solutions focus on two aspects of sound transmission mode and sound receiving equipment. There are currently two implementations:

Option 1: Use a general-purpose teaching loudspeaker. The lecturer wears a general-purpose teaching loudspeaker. The working principle of this kind of loudspeaker is to convert the sound wave received by the microphone into an electrical signal and amplify the weak signal through the combination of electronic components, and finally emit sound waves through the speaker to make the sound pass through. The permeability is stronger.

The defect of the first solution is: the field sound reinforcement effect is poor. The power of general-purpose teaching loudspeakers is about 3W~8W, which can increase the volume of human voices. In a quiet environment, the coverage area is 400 square meters. When the power of the loudspeaker is low or the surrounding environment is noisy, the sound amplification effect will be reduced. The results of the field test in the workshop factory practice base show that the actual distance that can accurately hear the speech of the lecturer is within 2 meters, and the practice class is a small class with about 30 students. The number of people accommodated within this distance range is small, especially in the classroom. There are fewer people when explaining around large-scale equipment, which cannot achieve the ideal teaching effect.

Option 2: Portable FM FM transmitter is used in conjunction with terminal equipment such as radios. The working principle of the portable FM FM transmitter worn by the lecturer is to modulate the audio signal and the high-frequency carrier into a FM wave, so that the frequency of the high-frequency carrier changes with the audio signal, and then amplify, excite, and The power amplifier is matched with a series of impedances, so that the signal output is sent to the antenna.

Terminal equipment such as radios worn by students can receive high-frequency signals from the antenna and restore them to audio signals through detection (demodulation), and send them to earphones or speakers to become sound waves.

The disadvantages of option two are:

1. Universal radio cannot be used. The frequency range of commercial FM broadcasting in my country is 88~108MHz, and the frequency range of campus broadcasting is 76~87MHz. The adjustable working range of the portable FM FM transmitter is 76~108MHz. The general radios on the market can receive the whole band, but the FM FM receiving range is 87 or 87.5~108MHz. Since the maximum power of the portable FM FM transmitter is 800mW, and the maximum operating distance is 800 meters (open visual distance), although the work in the commercial range (88-108MHz) has little impact, it cannot interfere with other people's legal business activities based on morality, so it is not allowed Use the commercial FM radio frequency and the school radio frequency (76~87MHz). Therefore, the supporting terminal receiving equipment excludes general-purpose radios and smart phones (with FM radio function) that only receive commercial FM frequency bands, and selects full-band radios with campus broadcast channels.

2. The radio is inconvenient to carry. The radio selected by the students is mainly used to listen to the campus radio and the CET-4 and CET-6 exams. In order to ensure various functions and radio quality, the overall precision is thick, the size is roughly 75*115*29mm, and the weight is about 206g (excluding batteries. ). As a student visiting for an internship, you need to write with a pen and take some notes, so you can’t hold a radio of this size, and it will feel clumsy and uncomfortable if you put it in your pocket, and it is easy to drop it, especially in summer when you wear loose and breathable clothes without pockets.

3. The quality of the radios brought by students is uneven, and the frequency bands need to be adjusted manually in advance, and there are too many functions irrelevant to teaching. It goes against the original intention of improving the teaching effect.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a receiving device for wireless teaching.

The purpose of the present invention is achieved through the following technical solutions:

A receiving device for wireless teaching, including a single-chip microcomputer, and a digital FM radio module connected to the single-chip microcomputer, an LED display and button control module, and a power switch module, wherein the single-chip microcomputer and the digital FM radio module are connected through the I2C serial data bus interface. The communication, LED display and button control module sends the change of button trigger level to the single-chip microcomputer, and the single-chip microcomputer sends corresponding instructions accordingly.

The single-chip microcomputer connects four buttons KEY1, KEY2, KEY3, and KEY4 to receive level changes through four pins of PC3, PC4, PC5, and PC6, and controls LED1, LED2, LED3, and The four LED lights of LED4 are on and off; the two transmission lines of the I2C bus standard, the SDA serial data line and the SCL clock line, are connected to the digital FM radio module. The other ends of the micro-touch buttons KEY1, KEY2, KEY3, and KEY4 are grounded, two of which are channel switching function buttons, and the other two are volume increase and decrease function buttons. The single-chip microcomputer detects the triggering of the key level in real time. When a certain pin of PC3, PC4, PC5, and PC6 is detected as low level, the software delays and debounces and detects again to confirm that a corresponding key has been pressed, and sends a corresponding command. The channel switching instruction is to change the channel register value of the digital FM radio module after the single-chip microcomputer detects that the channel switching function button is pressed, and makes the corresponding LED light on and off. There are four preset channels, and each time the channel switching button is detected, the next channel will be switched to the left (right), and all channels will be switched in a cycle. The volume increase and decrease command is to detect that the volume increase and decrease function button is pressed, and the single-chip microcomputer correspondingly changes the volume register value of the digital FM radio module. , does not increase or decrease cyclically.

The power switch module includes a switch, a lithium battery, a Micro-USB interface, and a resistor R8. The switch has two pins BAT and VCC, wherein the pin BAT is connected to the positive pole of the lithium battery, and the pin VCC is connected to the single-chip power supply pin VDD , the negative poles of all modules are grounded to GND, and the Micro-USB interface is connected to the power switch module pin BAT through a series resistor R8 to realize the charging function.

The LED display and button control module includes LED1, LED2, LED3, LED4, buttons KEY1, KEY2, KEY3, KEY4, and resistor R2, wherein one end of LED1, LED2, LED3, and LED4 connected in parallel is connected to the resistor R2 for current limiting. One end is connected, the other end of LED1, LED2, LED3, LED4 is respectively connected to the four pins of PC1, PD2, PD3, PA3 of the single chip microcomputer, and the other end of resistor R2 is connected to the switch pin VCC of the power switch module; keys KEY1, KEY2 , KEY3, and KEY4 are respectively connected to the four pins of the single-chip microcomputer PC3, PC4, PC5, and PC6, and the other ends of the keys KEY1, KEY2, KEY3, and KEY4 share the ground.

The digital FM radio module includes a chip U2, a crystal oscillator Y2, a magnetic bead F1, a magnetic bead F2, a capacitor C10, a capacitor C13, a capacitor C14, an earphone inlet EAR, and an earphone, wherein the pin RCLK of the chip U2 is externally connected to the crystal oscillator Y2 to provide a clock signal , The left channel output LOUT is connected in series with the capacitor C13 and magnetic bead F1 and connected to the EAR_L of the earphone inlet, the right channel output ROUT is connected in series with the capacitor C14 and the magnetic bead F2 and connected to the EAR_R of the earphone inlet, and the earphone is inserted into the earphone inlet EAR; the I2C bus serial data transmission line SDA and the clock line SCL of the chip U2 are respectively connected to the I2C_SDA interface and the I2C_SCL interface of the microcontroller, and the FM antenna interface FMIN and the capacitor C10 of the chip U2 are connected to the earphone inlet EAR_R. The single-chip channel switching command is transmitted to the digital FM radio module through the I2C communication protocol, and the chip U2 filters and receives the FM broadcast signal received by the earphone as an antenna according to the reading of the channel register value, and detects and decodes the received designated FM broadcast signal. tune output. The combination of the filter capacitor in the channel output line and the magnetic beads that can suppress high-frequency noise and spike interference can ensure the normal sound quality of the output signal transmitted to the earphone and converted into sound waves to the greatest extent.

The single-chip microcomputer is STMicroelectronics STM8 single-chip microcomputer, and its specific model is STM8S003; the model of the digital FM radio module is RDA5807M, and the digital FM radio module is RDA5807M. The single-chip microcomputer can also be other models, and the STM8 single-chip microcomputer is selected to be smaller in size, easy to carry, and lower in cost, which is conducive to mass production and application.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The key point of the present invention is to adopt the combination of STM8 and RDA5807M digital FM radio module, programming to limit only receiving designated channels (the channel range is between 76-87MHz of campus FM radio), and to cooperate with the portable FM transmitter to realize unidirectional sound Information transfer. Using a chip with a high degree of integration, it is small in size and light in weight.

2. The implementation plan of the prior art is the supporting use of a radio with a campus broadcast frequency band and a portable FM transmitter. In terms of technology, the traditional analog radios on the market have gradually withdrawn from the stage and replaced by digital integrated radios with DSP technology. This generation of radios is more sophisticated and has higher radio quality, but the volume of precision components is difficult to compress, and the cost is higher. The finished product is larger. However, the present invention simplifies functions while ensuring normal radio quality, adopts the combination of a newer digital FM radio chip and a single-chip microcomputer, and the higher degree of integration allows the volume and quality to be significantly reduced. The function is simple, the radio quality is good, the transmission range is wide and stable by using FM broadcasting technology, and the signal is received by using a limited number of channels;

3. The main application of the present invention is to clearly receive sound information in one direction in noisy environments such as workshops and factories. The audience is college students who participate in internships in noisy environments such as workshops and factories. The low price is suitable for mass production promotion.

4. The earphone cable of the existing portable FM frequency modulation transmitter is too long. During the students' visit and practice, the long earphone wires may be hooked, wrapped or entangled with mechanical equipment, which will affect the normal operation of the workshop and factory equipment, and seriously cause students' personal safety problems. The wireless teaching receiving device of the present invention is simplified to only four channels and volume increase and decrease, and is changed to a single earplug type, the length of the earphone line is shortened, and the receiving device is light in weight and can be hung on the chest.

Description of drawings

Fig. 1 is a schematic structural diagram of a receiving device for wireless teaching according to the present invention;

Fig. 2 is a circuit diagram of the receiving device described in Fig. 1;

Fig. 3 is the circuit diagram of the single-chip microcomputer of the receiving device described in Fig. 2 and its auxiliary circuit;

Fig. 4 is a circuit diagram of a power switch module of the receiving device described in Fig. 2;

Fig. 5-1 is the LED display circuit diagram of the LED display and button control module of the receiving device described in Fig. 2;

Figure 5-2 is a circuit diagram of the LED display and key control module of the receiving device described in Figure 2;

FIG. 6 is a circuit diagram of a digital FM radio module of the receiving device shown in FIG. 2 .

Detailed ways

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

As shown in Figures 1 and 2, a receiving device for wireless teaching includes a single-chip microcomputer, a digital FM radio module connected to the single-chip microcomputer, an LED display and key control module, and a power switch module. The serial data bus interface communicates, and the LED display and button control module sends the change of the trigger level of the button to the single-chip microcomputer, and the single-chip microcomputer sends corresponding instructions accordingly;

As shown in Figure 3, the single-chip microcomputer connects four buttons KEY1, KEY2, KEY3, KEY4 to receive level changes through four pins PC3, PC4, PC5, and PC6, and controls LED1, The four LED lights LED2, LED3, and LED4 are on and off; the two transmission lines SDA serial data line and SCL clock line of the I2C bus standard are connected to the digital FM radio module; the capacitor C1 is used as the core voltage decoupling capacitor and connected to the pin VAP, Ensure the stability of the voltage regulator; capacitor C2 is connected to the pin VCC as a filter capacitor to filter out the clutter and AC components of the power supply to prevent the power from introducing interference and parasitic oscillations.

As shown in Figure 4, the power switch module includes a switch, a lithium battery, a Micro-USB interface, and a resistor R8. The switch has two pins BAT and VCC, wherein the pin BAT is connected to the positive pole of the lithium battery, and the pin VCC is connected to the single-chip power supply. The pin VDD is connected, the negative poles of all modules are grounded to GND, and the Micro-USB interface is connected to the power switch module pin BAT through the series resistor R8 to realize the charging function;

As shown in Figures 5-1 and 5-2, the LED display and button control module includes LED1, LED2, LED3, LED4, buttons KEY1, KEY2, KEY3, KEY4, and resistor R2, where LED1, LED2, LED3, and LED4 are connected in parallel One end is connected to one end of resistor R2 for current limiting, the other end of LED1, LED2, LED3, LED4 is respectively connected to the four pins of PC1, PD2, PD3, PA3 of the single chip microcomputer, and the other end of resistor R2 is connected to the pin of the power switch module. The switch pins are connected to VCC; one end of the keys KEY1, KEY2, KEY3, and KEY4 are connected to the four pins of the single-chip microcomputer PC3, PC4, PC5, and PC6 respectively, and the other ends of the keys KEY1, KEY2, KEY3, and KEY4 share the ground.

As shown in Figure 6, the digital FM radio module includes chip U2, crystal oscillator Y2, magnetic bead F1, magnetic bead F2, capacitor C10, capacitor C13, capacitor C14, earphone inlet EAR, earphone, wherein the pin RCLK of the chip U2 is externally connected to the crystal oscillator Y2 provides the clock signal, the left channel output LOUT is connected in series with capacitor C13 and magnetic bead F1 and connected to EAR_L of the headphone inlet, the right channel output ROUT is connected in series with capacitor C14 and magnetic bead F2 and connected to EAR_R of the headphone inlet. Insert the earphone inlet EAR; the I2C bus serial data transmission line SDA and the clock line SCL of the chip U2 are respectively connected to the I2C_SDA interface and the I2C_SCL interface of the microcontroller, and the FM antenna interface FMIN and the capacitor C10 of the chip U2 are connected to the earphone inlet EAR_R;

Described single-chip microcomputer is STMicroelectronics STM8 single-chip microcomputer, and its specific model is STM8S003; The model of described digital FM radio module is RDA5807M, and digital FM radio module is RDA5807M;

The parameters of the components involved are as follows: capacitor C1 is 1uf, capacitor C2 is 0.1uf, capacitor C10 is 100pf, capacitor C13 is 4.7uf, capacitor C14 is 4.7uf, resistor R2 is 1k ohms, resistor R8 is 20 ohms, magnetic The bead F1 is 15K100M, the magnetic bead F2 is 15K100M, and the crystal oscillator is 32.768kHz.

In terms of sound transmission, we use a portable FM transmitter, the working range of which is the campus FM radio frequency band (76 ~ 87MHz). FM broadcasting is a broadcasting technology in which the frequency of high-frequency oscillation changes with the amplitude of the audio signal. It has the advantages of strong anti-interference and low distortion. The propagation medium of radio waves is air, and the propagation distance is long. Specific to this portable FM FM transmitter, its transmission distance is 800 meters (open visual distance) when it works at maximum power, and the field test in a noisy environment is about 400 meters. This solves the problem of limiting the number of students in the venue.

In terms of terminal receiving equipment, the wireless teaching receiving equipment is powered by a lithium battery, and has four built-in channels (between 76 and 87MHz, which have been set before leaving the factory). The channel increases and decreases the volume up and down, four LEDs are arranged in a line above the button, the headphone jack is on the top of the body, the Micro-USB charging socket is on the bottom, and the switch is on the right.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (6)

1. A receiving device for wireless teaching, characterized in that: comprise single-chip microcomputer, and digital FM radio module, LED display and button control module, power switch module connected with single-chip microcomputer respectively, wherein single-chip microcomputer and digital FM radio module pass I2C The serial data bus interface communicates, and the LED display and button control module sends the change of the trigger level of the button to the single-chip microcomputer, and the single-chip microcomputer sends corresponding instructions accordingly. 2. The receiving device for wireless teaching according to claim 1, characterized in that: said single-chip microcomputer connects four keys KEY1, KEY2, KEY3, KEY4 through four pins of PC3, PC4, PC5, and PC6 to receive level Change, through the four pins of PC1, PD2, PD3, PA3 to control the four LED lights of LED1, LED2, LED3, LED4 to turn on and off; through the two transmission lines of I2C bus standard SDA serial data line, SCL clock line and digital FM radio module connected. 3. The receiving device for wireless teaching according to claim 1, wherein the power switch module includes a switch, a lithium battery, a Micro-USB interface, and a resistor R8, and the switch has two pins BAT and VCC , where the pin BAT is connected to the positive pole of the lithium battery, the pin VCC is connected to the single-chip power supply pin VDD, the negative poles of all modules are grounded to GND, and the Micro-USB interface is connected to the power switch module pin BAT through a series resistor R8 to realize the charging function. 4. The receiving device for wireless teaching according to claim 1, characterized in that: said LED display and button control module includes LED1, LED2, LED3, LED4, buttons KEY1, KEY2, KEY3, KEY4, resistor R2, One end of LED1, LED2, LED3, and LED4 connected in parallel is connected to one end of resistor R2 for current limiting, and the other ends of LED1, LED2, LED3, and LED4 are respectively connected to four pins of PC1, PD2, PD3, and PA3 of the single-chip microcomputer. , the other end of the resistor R2 is connected to the switch pin VCC of the power switch module; one end of the buttons KEY1, KEY2, KEY3, and KEY4 are respectively connected to the four pins of the single-chip microcomputer PC3, PC4, PC5, and PC6, and the buttons KEY1, KEY2, KEY3, The other end of KEY4 shares the ground. 5. The receiving device for wireless teaching according to claim 1, characterized in that: said digital FM radio module includes chip U2, crystal oscillator Y2, magnetic bead F1, magnetic bead F2, capacitor C10, capacitor C13, capacitor C14 , earphone inlet EAR, earphone, in which the pin RCLK of the chip U2 is externally connected to the crystal oscillator Y2 to provide the clock signal, the left channel output LOUT is connected in series with the capacitor C13 and the magnetic bead F1 and connected to the EAR_L of the earphone inlet, and the right channel output ROUT and Capacitor C14 and magnetic bead F2 are connected in series to EAR_R of the earphone inlet, and the earphone is inserted into the earphone inlet EAR; the I2C bus serial data transmission line SDA and the clock line SCL of the chip U2 are respectively connected to the I2C_SDA interface and the I2C_SCL interface of the single-chip microcomputer, and the chip U2’s The FM antenna interface FMIN and the capacitor C10 are connected to the earphone interface EAR_R. 6. The receiving device for wireless teaching according to any one of claims 1 to 5, characterized in that: the single-chip microcomputer is STMicroelectronics STM8 single-chip microcomputer, and its specific model is STM8S003; the model of the digital FM radio module It is RDA5807M, and the digital FM radio module is RDA5807M.