School bus fire alarm and child anti-retention circuit based on 51 single-chip microcomputer

Abstract

The utility model provides a school bus fire alarm and child anti-retention circuit based on 51 single-chip microcomputer belongs to school bus in safety alarm circuit technical field, including minimum single-chip microcomputer circuit, fire alarm circuit, child anti-retention circuit, audible and light alarm circuit and power supply circuit, this circuit can send out the alarm when the fire and child retention in school bus can take place, reminds relevant personnel, reduces the possibility of safety accident occurrence.

Description

Technical Field

[0001] This utility model belongs to the field of alarm circuit technology, specifically relating to a school bus fire alarm and child prevention circuit based on a 51 microcontroller. Background Technology

[0002] School buses are the primary means of transportation for students to and from school, and their safety is of paramount importance. Because children often have weak safety awareness, limited self-rescue abilities, and limited capacity to express danger, they are more likely to experience serious accidents when a fire breaks out on a school bus or when children are left unattended.

[0003] Currently, there are no technologies for designing fire alarms and child occupancy alarms on school buses. Therefore, it is necessary to design relevant fire alarm and child occupancy alarm circuits to serve as an alarm in case of the aforementioned safety incidents and reduce losses. Utility Model Content

[0004] This invention proposes a school bus fire alarm and child protection circuit based on a 51 microcontroller, which can issue an alarm to remind relevant personnel when a fire occurs inside the school bus or when children are left behind.

[0005] To achieve the above objectives, the present invention proposes the following technical content: The school bus fire alarm and child protection circuit based on 51 microcontroller includes a minimum microcontroller circuit, a fire alarm circuit, a child protection circuit, an audible and visual alarm circuit, and a power supply circuit. The smallest single-chip microcomputer circuit uses the STC89C52 single-chip microcomputer; the fire alarm circuit includes: MQ-2 smoke sensor circuit, DS18B20 temperature sensor circuit and ADC0832 analog-to-digital converter circuit; the child protection circuit uses an infrared sensor circuit. The MQ-2 smoke sensor circuit includes: an MQ-2 sensor unit; pins 1 and 2 of the MQ-2 sensor unit are connected in parallel to the power supply VCC; pin 5 is grounded; pin 6 of the MQ-2 sensor unit is connected to pin 2 of the ADC0832 analog-to-digital converter unit; and pin 6 of the MQ-2 sensor unit, after being connected in parallel with an adjustable resistor R12, is connected to pin 4 of the ADC0832 analog-to-digital converter unit; pin 8 of the ADC0832 analog-to-digital converter unit is connected to the power supply VCC, pin 4 is grounded, pin 1 is connected to pin 23 of the STC89C52 microcontroller, pin 7 is connected to pin 22 of the STC89C52 microcontroller, and pins 5 and 6, after being connected in parallel, are connected to pin 21 of the STC89C52 microcontroller. The DS18B20 temperature sensor circuit includes: a pull-up resistor R11, which is connected in parallel across pins 2 and 3 of the DS18B20 temperature sensor unit; pins 1 and 3 of the DS18B20 temperature sensor unit are grounded and connected to the power supply VCC, respectively; and pin 2 of the DS18B20 sensor unit is connected to pin 5 of the STC89C52 microcontroller. The infrared sensor circuit includes: a DYP-ME003 infrared sensor unit; pins 3 and 1 of the infrared sensor unit are connected to power supply VCC and ground, respectively; pin 2 of the DYP-ME003 infrared sensor unit is connected to one end of resistor R15, the other end of resistor R15 is connected to the base of NPN transistor Q4, the collector of transistor Q4 is connected to pin 25 of STC89C52 microcontroller, and the emitter of transistor Q4 is grounded.

[0006] Furthermore, it also includes a GSM SMS transmission circuit, which includes: a SIM800 SMS sending unit U14; pin 1 of the SIM800 SMS sending unit U14 is grounded, and pin 1 and pin 5 are connected through capacitor C4; the SIM800 SMS sending unit U14 is connected to the power supply VCC through diode D1; pins 2 and 3 of the SIM800 SMS sending unit are connected to pins 10 and 11 of the STC89C52 microcontroller, respectively.

[0007] Furthermore, the audible and visual alarm circuit includes: The transistor U7 is a PNP transistor. The emitter of U7 is connected to the power supply VCC, and the base is connected to pin 24 of the STC89C52 microcontroller through resistor R5. The buzzer U8 is connected at one end to the collector of transistor U7 and at the other end to ground. Resistor R7 and LED L5 are connected in series between the two ends of buzzer U8. The collector of transistor U7 is connected in parallel with resistor R7. The connection point M between transistor U7 and buzzer U8 and LED L5 are connected to the two ends of resistor R7 respectively.

[0008] Furthermore, the power supply circuit includes a SWITCH unit U4, whose pin 3 is connected to the power supply VCC; a power supply regulator unit U5, whose pin 1 is connected to pin 1 of the SWITCH unit U4, pin 2 is grounded, and pin 3 of the power supply regulator unit U5 is connected to the power supply VCC of other circuit modules in this system.

[0009] Furthermore, it also includes a display circuit, which includes an LCD1602 liquid crystal display screen U2; pins 1 and 16 of the display screen are grounded, and pins 2 and 15 are connected to the power supply VCC; a variable resistor RT1 is connected between pins 1 and 3; pins 7 to 14 are respectively connected to pins 39 to 32 of the STC89C52 microcontroller; pins 4 to 6 are respectively connected to pins 26 to 28 of the STC89C52 microcontroller; and a resistor array unit U3, whose pins 1 to 9 are respectively connected to pins 40 to 32 of the STC89C52 microcontroller, and whose pin 1 is connected to the power supply VCC.

[0010] The beneficial effects that can be achieved by adopting the above technical solution are: This circuit enables dual safety monitoring for school bus fires and children being stranded. In a fire scenario, an alarm is triggered if either the temperature or smoke exceeds the standard. In a stranded scenario, the circuit automatically detects human heat sources after the engine is turned off and the doors are closed. This effectively addresses the core pain points of children's weak safety awareness and insufficient self-rescue ability, reducing the risk of safety accidents. The alarm response combines local audio-visual alerts with remote GSM SMS push notifications, enabling timely alerts to people around the vehicle for on-site handling, while also allowing pre-set management personnel to remotely monitor the alarm status and environmental parameters, achieving dual protection of "on-site + remote"; The circuit uses the STC89C52 microcontroller as its core and is equipped with mature sensors such as DS18B20 and MQ-2. The module connection is simple and the cost is controllable. It also supports multi-sensor cascading and sensitivity adjustment, adapting to the needs of different monitoring areas of school buses and is highly practical. Attached Figure Description

[0011] Figure 1 This is the circuit diagram for fire alarm and child safety features; Figure 2 It is the smallest single-chip microcontroller circuit; Figure 3 It is a temperature sensor circuit; Figure 4 It is a smoke sensor circuit; Figure 5 It is an infrared sensor circuit; Figure 6 It is a GSM SMS transmission circuit; Figure 7 It is a display circuit; Figure 8 It is an audible and visual alarm circuit; Figure 9 It is a power supply circuit. Detailed Implementation

[0012] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0013] like Figure 1 As shown, the school bus fire alarm and child protection circuit based on the 51 microcontroller includes a minimum microcontroller circuit, a fire alarm circuit, a child protection circuit, a GSM SMS transmission circuit, a display circuit, an audible and visual alarm circuit, and a power supply circuit.

[0014] See Figure 2 The smallest microcontroller circuit uses an STC89C52 microcontroller. It features an 8-bit CMOS microcontroller, 8KB of programmable Flash memory, and includes a crystal oscillator and a reset circuit to ensure normal operation.

[0015] See Figure 3 and Figure 4 The fire alarm circuit includes an MQ-2 smoke sensor circuit, a DS18B20 temperature sensor circuit, and an ADC0832 analog-to-digital converter circuit.

[0016] See Figure 3 The DS18B20 temperature sensor circuit includes: DS18B20 temperature sensor unit; A pull-up resistor R11 is connected in parallel across pins 2 and 3 of the DS18B20 temperature sensor unit. Pins 1 and 3 of the DS18B20 temperature sensor unit are grounded and connected to the power supply VCC, respectively. Pin 2 of the DS18B20 sensor unit is connected to pin 5 of the STC89C52 microcontroller. The temperature data monitored by the DS18B20 temperature sensor is transmitted to the STC89C52 microcontroller.

[0017] See Figure 4 The ADC0832 analog-to-digital converter circuit includes: The ADC0832 analog-to-digital converter (ADC) is configured with its pin 8 connected to the power supply VCC and pin 4 grounded. Pin 1 of the ADC0832 is connected to pin 23 of the STC89C52 microcontroller. Pin 7 of the ADC0832 is connected to pin 22 of the STC89C52 microcontroller. Pins 5 and 6 of the ADC0832 are connected in parallel to pin 21 of the STC89C52 microcontroller.

[0018] The MQ-2 smoke sensor circuit includes: MQ-2 sensor unit U13; pins 1 and 2 of unit U13 are connected in parallel and then connected to the power supply VCC; pin 5 is grounded to enable the MQ-2 sensor unit. Pin 6 of the MQ-2 sensor unit is connected to pin 2 of the ADC0832 analog-to-digital converter unit, and pin 6 of the MQ-2 sensor unit, after being connected in parallel with an adjustable resistor R12, is connected to pin 4 of the ADC0832 analog-to-digital converter unit. The smoke concentration data monitored by the MQ-2 sensor unit U13 is transmitted to the STC89C52 microcontroller after analog-to-digital conversion.

[0019] The smoke sensor is installed inside the school bus to monitor smoke concentration. Its working principle is based on the scattering effect of smoke particles on the air. When smoke enters the sensor, the smoke particles scatter light, causing a change in the light intensity received by the photosensitive element, thus outputting an analog signal. This analog signal is converted into a digital signal by the ADC0832 analog-to-digital converter chip and sent to the microcontroller for processing. The adjustable resistor R12 on the MQ-2 sensor module can adjust the sensitivity to smoke. After installation, rotating the upper adjustment lever of the adjustable resistor R12 clockwise (increasing the resistance) will decrease the sensitivity of the MQ-2 sensor unit, suitable for high-concentration smoke scenarios; rotating the upper adjustment lever of the adjustable resistor R12 counterclockwise (decreasing the resistance) will increase the sensitivity of the MQ-2 sensor unit, suitable for low-concentration smoke scenarios. Installers can configure the sensitivity of multiple MQ-2 sensor units appropriately based on their experience.

[0020] The temperature sensor is used to monitor the temperature inside the vehicle. Its working principle is based on the thermistor effect of semiconductors. When the temperature changes, the sensor's resistance changes; the temperature value is obtained by measuring this change in resistance. The temperature measurement range is -10°C to +85°C, with an accuracy of ±0.5°C. The DS18B20 temperature sensor uses a single-bus communication method, requiring only one data cable for communication, simplifying wiring. It supports cascading of multiple devices, allowing multiple sensors to be installed collaboratively in a school bus to monitor temperature.

[0021] See Figure 5The child safety circuit uses an infrared sensor circuit. The infrared sensor circuit includes: The DYP-ME003 infrared sensor unit has pins 3 and 1 connected to power supply VCC and ground respectively to enable it. Pin 2 is connected to one end of resistor R15, and the other end of R15 is connected to the base of NPN transistor Q4 (8050 model). The collector of transistor Q4 is connected to pin 25 of the STC89C52 microcontroller, and the emitter of transistor Q4 is grounded.

[0022] The infrared sensor detects infrared radiation emitted by the human body through the pyroelectric effect, covering the entire vehicle without blind spots. The system initiates scanning after the school bus is turned off and the doors are closed. If a human body's heat radiation signal is detected, the sensor outputs an electrical signal. This signal is amplified and sent to the microcontroller for processing, triggering an alarm. In this embodiment, considering that the DYP-ME003 infrared sensor unit can basically complete the monitoring of personnel lingering, no additional sensors of other types are added for auxiliary monitoring. In other embodiments, to ensure monitoring accuracy, a sound monitoring module can be connected to the microcontroller to cooperate with the DYP-ME003 infrared sensor unit in monitoring for the presence of lingering personnel.

[0023] See Figure 8 The audible and visual alarm circuit includes: The PNP transistor U7 has its emitter connected to the power supply VCC and its base connected to pin 24 of the STC89C52 microcontroller via resistor R5. Buzzer U8 is connected at one end to the collector of transistor U7 and at the other end to ground. A resistor R7 and an LED L5 are connected in series between the two ends of buzzer U8. The collector of transistor U7 is connected in parallel with resistor R7, and the connection point M between transistor U7 and buzzer U8 and LED L5 are connected to the two ends of resistor R7 respectively.

[0024] See Figure 6 The GSM SMS transmission circuit includes: The SIM800 SMS sending unit U14 has its pin 1 grounded, and pin 1 is connected to pin 5 via capacitor C4. The SIM800 SMS sending unit U14 is connected to the power supply VCC via diode D1. Pins 2 and 3 of the SIM800 SMS sending unit are connected to pins 10 and 11 of the STC89C52 microcontroller, respectively.

[0025] This module features SMS messaging, voice calls, and GPRS data transmission. When a fire alarm or child safety alarm is triggered, the microcontroller sends an AT command to the GSM SMS transmission circuit via serial port, and the GSM SMS transmission circuit then sends the alarm information to a preset mobile phone number.

[0026] See Figure 7 The display circuit includes: LCD1602 LCD display U2; pins 1 and 16 of this display are grounded, and pins 2 and 15 are connected to the power supply VCC; a variable resistor RT1 is connected between pins 1 and 3. Pins 7-14 are connected to pins 39-32 of the STC89C52 microcontroller, respectively. Pins 4-6 are connected to pins 26-28 of the STC89C52 microcontroller, respectively.

[0027] The resistor array unit U3 has pins 1 to 9 connected to pins 40 to 32 of the STC89C52 microcontroller, and pin 1 of the resistor array unit U3 is connected to the power supply VCC. The resistor array unit U3 is used to ensure the stability of the LCD1602 liquid crystal display screen U2.

[0028] See Figure 9 The power supply circuit includes: SWITCH unit U4; its pin 3 is connected to power supply VCC. When SWITCH unit U4 receives a start signal from the vehicle controller, it remains on. After being on, it provides a stable power supply to the entire system of this solution through power supply regulator unit U5.

[0029] The power supply regulator unit U5 has its pin 1 connected to pin 1 of the SWITCH unit U4, and its pin 2 grounded. Pin 3 of the power supply regulator unit U5 is connected to the power supply VCC of other circuit modules in this system. Thus, the power supply module is used to provide a stable power supply for the entire system. This system uses a 5V DC power supply, and the voltage regulator circuit stabilizes the power supply voltage at around 5V to ensure the normal operation of each module.

[0030] Alarm process of this circuit Temperature and smoke concentration sensors in the fire alarm circuit monitor the air temperature and smoke concentration inside the vehicle, respectively, and transmit the data to the STC89C52 microcontroller. The microcontroller compares the actual monitored data with preset thresholds for both sensors. If either exceeds the threshold, a fire alarm is triggered. Subsequently, the microcontroller controls the audible and visual alarm circuit to issue an audible and visual alarm, and displays the current environmental parameters (temperature and smoke concentration) and alarm status (fire) on the LCD1602 liquid crystal display screen U2 of the display circuit. The microcontroller also sends the environmental parameters and alarm status to a preset mobile phone number via a GSM SMS transmission circuit.

[0031] When the vehicle is turned off and the doors are closed, the vehicle controller sends a parking lock signal to the microcontroller in this solution. Upon receiving this signal, the microcontroller begins processing the data fed back from the child safety circuit. For example, if the infrared sensor detects a heat source inside the vehicle after the engine is off and the doors are closed, the microcontroller controls the audible and visual alarm circuit to issue an alarm and displays the current environmental parameters (temperature and smoke concentration) and alarm status (person trapped) on the LCD1602 display screen U2. The microcontroller also sends these environmental parameters and alarm status to a preset mobile phone number via a GSM SMS transmission circuit. In this circuit, an audible and visual alarm circuit alerts people near the vehicle to respond promptly to the school bus's alarm status (fire or stranded passengers), thereby reducing the likelihood of a school bus accident. Additionally, a GSM SMS transmission circuit alerts relevant personnel with pre-registered mobile phone numbers to respond promptly to the school bus's alarm status (fire or stranded passengers), enabling them to take appropriate measures to mitigate the possibility of a school bus accident.

[0032] Based on the above-described preferred embodiments of this utility model, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the technical concept of this utility model. The technical scope of this utility model is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A school bus fire alarm and child prevention circuit based on a 51 microcontroller, characterized in that, Includes a minimum single-chip microcomputer circuit, a fire alarm circuit, a child safety protection circuit, an audible and visual alarm circuit, and a power supply circuit; The smallest microcontroller circuit uses the STC89C52 microcontroller; the fire alarm circuit includes: an MQ-2 smoke sensor circuit, a DS18B20 temperature sensor circuit, and an ADC0832 analog-to-digital converter circuit; the child safety circuit uses an infrared sensor circuit; the ADC0832 analog-to-digital converter circuit includes an ADC0832 analog-to-digital conversion unit. The MQ-2 smoke sensor circuit includes: an MQ-2 sensor unit; pins 1 and 2 of the MQ-2 sensor unit are connected in parallel to the power supply VCC; pin 5 is grounded; pin 6 of the MQ-2 sensor unit is connected to pin 2 of the ADC0832 analog-to-digital converter unit; and pin 6 of the MQ-2 sensor unit, after being connected in parallel with an adjustable resistor R12, is connected to pin 4 of the ADC0832 analog-to-digital converter unit; pin 8 of the ADC0832 analog-to-digital converter unit is connected to the power supply VCC; pin 4 is grounded; pin 1 is connected to pin 23 of the STC89C52 microcontroller; pin 7 is connected to pin 22 of the STC89C52 microcontroller; and pins 5 and 6, after being connected in parallel, are connected to pin 21 of the STC89C52 microcontroller. The DS18B20 temperature sensor circuit includes: a pull-up resistor R11, which is connected in parallel across pins 2 and 3 of the DS18B20 temperature sensor unit; pins 1 and 3 of the DS18B20 temperature sensor unit are grounded and connected to the power supply VCC, respectively; and pin 2 of the DS18B20 sensor unit is connected to pin 5 of the STC89C52 microcontroller. The infrared sensor circuit includes: a DYP-ME003 infrared sensor unit; pins 3 and 1 of the infrared sensor unit are connected to power supply VCC and ground, respectively; pin 2 of the DYP-ME003 infrared sensor unit is connected to one end of resistor R15, the other end of resistor R15 is connected to the base of NPN transistor Q4, the collector of transistor Q4 is connected to pin 25 of STC89C52 microcontroller, and the emitter of transistor Q4 is grounded.

2. The school bus fire alarm and child prevention circuit based on a 51 microcontroller according to claim 1, characterized in that, It also includes a GSM SMS transmission circuit, which includes: a SIM800 SMS sending unit U14; pin 1 of the SIM800 SMS sending unit U14 is grounded, and pin 1 and pin 5 are connected through capacitor C4; the SIM800 SMS sending unit U14 is connected to the power supply VCC through diode D1; pins 2 and 3 of the SIM800 SMS sending unit are connected to pins 10 and 11 of the STC89C52 microcontroller, respectively.

3. The school bus fire alarm and child prevention circuit based on a 51 microcontroller according to claim 1, characterized in that, The audible and visual alarm circuit includes: The transistor U7 is a PNP transistor. The emitter of U7 is connected to the power supply VCC, and the base is connected to pin 24 of the STC89C52 microcontroller through resistor R5. The buzzer U8 is connected at one end to the collector of transistor U7 and at the other end to ground. Resistor R7 and LED L5 are connected in series between the two ends of buzzer U8. The collector of transistor U7 is connected in parallel with resistor R7. The connection point M between transistor U7 and buzzer U8 and LED L5 are connected to the two ends of resistor R7 respectively.

4. The school bus fire alarm and child prevention circuit based on a 51 microcontroller according to claim 1, characterized in that, The power supply circuit includes a SWITCH unit U4, whose pin 3 is connected to the power supply VCC; a power supply regulator unit U5, whose pin 1 is connected to pin 1 of the SWITCH unit U4, pin 2 is grounded, and pin 3 of the power supply regulator unit U5 is connected to the power supply VCC of other circuit modules in this system.

5. The school bus fire alarm and child prevention circuit based on a 51 microcontroller according to claim 1, characterized in that, It also includes a display circuit, which includes an LCD1602 liquid crystal display screen U2; pins 1 and 16 of the display screen are grounded, and pins 2 and 15 are connected to the power supply VCC; a variable resistor RT1 is connected between pins 1 and 3; pins 7 to 14 are connected to pins 39 to 32 of the STC89C52 microcontroller respectively; pins 4 to 6 are connected to pins 26 to 28 of the STC89C52 microcontroller respectively; and a resistor array unit U3, whose pins 1 to 9 are connected to pins 40 to 32 of the STC89C52 microcontroller respectively, and pin 1 of the resistor array unit U3 is connected to the power supply VCC.

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