CN105424889B - The hand-held monitoring device of high accuracy open air CO concentration - Google Patents

Abstract

A high-precision outdoor CO concentration handheld monitoring device, the device includes an outer shell of the device, a circuit board; the circuit board includes a power switch, a UART interface, a USB charging interface, a lithium battery, an LCD display module, a CO concentration acquisition module, and a temperature and humidity sensor . The purpose of the present invention is to overcome the inconvenience of using the existing CO concentration monitoring system due to its large volume, weight, power consumption, and high price, and cannot meet the accuracy of CO concentration monitoring under natural conditions. For this reason the present invention has completed a kind of high-precision outdoor CO concentration hand-held monitoring equipment. The size of the terminal is only the size of a palm, and the weight is equivalent to that of a mobile phone. It is equipped with a CO gas sensor, which can sense the concentration of CO gas in the outdoor air under natural conditions, obtain high-precision CO concentration data, and display it in real time through the LCD screen.

Description

High-precision outdoor CO concentration handheld monitoring equipment

technical field

The invention relates to the field of gas concentration monitoring, in particular to the field of high-precision outdoor CO concentration monitoring.

Background technique

Air quality is an indispensable content in environmental monitoring, and carbon monoxide is the main content of air quality monitoring. At present, the commonly used air monitoring system can be installed in a fixed position to effectively monitor the concentration of main pollutant gases in the air, with excellent performance. However, the biggest problem of this type of air monitoring system is that the system is very large and takes up space; the power consumption is large, which increases energy consumption; the weight is also large, which is not convenient for mobile monitoring; Increased usage costs. Among them, for CO gas concentration, most of the domestic monitoring is for industrial production or monitoring of natural gas leakage. They are all used in environments with high CO concentration and are not sensitive to accuracy. Therefore, the accuracy of such equipment is relatively high. Poor, cannot be used for outdoor monitoring in natural conditions.

For this reason, the present invention completes a high-precision outdoor CO concentration handheld monitoring device.

Contents of the invention

The purpose of the present invention is to overcome the inconvenience of using the existing CO concentration monitoring system due to its large volume, weight, power consumption, and high price, and cannot meet the accuracy of CO concentration monitoring under natural conditions. For this reason the present invention has completed a kind of high-precision outdoor CO concentration hand-held monitoring equipment. The terminal is only palm-sized and weighs as much as a mobile phone. It is equipped with a CO gas sensor, which can sense the concentration of CO gas in the outdoor air under natural conditions, and obtain high-precision CO concentration data, which can be displayed in real time on the LCD screen.

The present invention can be realized through the following technical solutions:

A high-precision outdoor CO concentration handheld monitoring device, the device includes an outer shell of the device, a circuit board; the circuit board includes a power switch, a UART interface, a USB charging interface, a lithium battery, an LCD display module, a CO concentration acquisition module, and a temperature and humidity sensor .

The circuit main board of the equipment is fixed in the equipment housing, and the equipment housing is a regular cuboid; an LCD display screen is fixed in the middle of the front panel of the circuit main board above the inside of the equipment housing; the left side of the circuit main board inside the housing is provided with a power supply Switch, UART interface, USB charging interface; the CO concentration acquisition module is fixed on the right side of the upper circuit board inside the outer casing; the bottom of the circuit board inside the outer casing is provided with a lithium battery fixing device.

A high-precision outdoor CO concentration handheld monitoring device, the monitoring terminal includes four parts: power management part, MCU system control part, data acquisition and transmission part, LCD display part. Among them, the LCD display part is composed of TFT LCD and LCD backlight driving circuit. The power management part is composed of charging management circuit, power supply management circuit and battery voltage monitoring circuit. The data acquisition and transmission part is composed of CO concentration acquisition module, temperature and humidity sensor, and UART interface. The system control part is composed of MCU, reset, debugging interface and so on.

This device uses a single-cell lithium battery as the core of electric energy storage and supply, with MCU as the control core, which can be charged through USB, and powered by the power switch control system. The power supply of the system comes from a rechargeable lithium battery. This device connects the single-cell lithium battery output with the power management part to provide available high-quality power supply for MCU, LCD display, CO sensor module and other various circuit parts. The power supply requirements are met, and under the regulation of the MCU in the control part, the information of the gas to be measured sensed by the CO sensor is collected, read, transmitted and displayed.

The unit modules that realize the functions of the entire system are: MCU control unit, system reset unit, battery power acquisition unit, CO concentration acquisition module unit, temperature and humidity sensor unit, charging management unit, power supply management unit and LCD display unit. Among them, the MCU control unit is connected with other units, so that the entire device works in coordination, collects data, and enables the LCD display interface to display: monitoring CO concentration, ambient temperature and humidity, current battery voltage, and percentage of remaining battery power.

Each part of the module unit is described in detail below.

The MCU control unit includes an MCU chip, an MCU external circuit, a UART interface circuit and a status indicator LED.

The system reset unit includes a system reset button, a reset resistor, and a reset capacitor.

The battery power acquisition unit includes a power acquisition enabling circuit and a battery voltage divider circuit.

The sensor unit includes a temperature and humidity sensor circuit and a CO concentration acquisition module circuit.

The charging control unit includes a USB interface and a USB charging management circuit.

The power supply control unit sequentially includes a DC-DC boost circuit, a 3.3V LDO step-down regulator circuit, and a 5V LDO step-down regulator circuit.

The LCD display unit includes a TFT LCD and an LCD backlight drive circuit, and the LCD backlight drive circuit drives the TFT LCD.

Compared with the prior art, the present invention can obtain the following beneficial effects.

Compared with various current air quality monitoring terminal systems, the present invention can set a USB interface to charge the built-in lithium battery, and the application of the lithium battery increases the mobility and portability of the equipment. The circuit part of the present invention adopts low power consumption chip design, the whole system operates under very low power consumption, saves the use of battery power, and enables the device to work for a long time under the condition of pure battery power supply. The invention can realize the real-time monitoring and display of high-precision outdoor CO concentration, and the temperature, humidity and CO concentration of the air can be displayed through the LCD screen, which is convenient for observation. The present invention can be used as a hand-held device, placed indoors or outdoors and in other places where monitoring is required. The invention not only can directly display the collected data value on the LCD of the device, but also can connect the computer through the UART, display the data through the display, or process the collected data. The invention can be used as a handheld monitoring device and a high-precision outdoor CO monitoring device, and has the characteristics of high precision, small size, light weight, convenient mobile monitoring, and low power consumption.

Description of drawings

Fig. 1 is the structural connection diagram of the circuit of the present invention;

Fig. 2 is a structural connection diagram of the CO concentration acquisition module of the present invention;

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

For the schematic circuit diagram of the control part of the MCU system of the present invention, the corresponding circuit schematic diagram is designed according to the requirements of the MCU data manual used, and then the printed circuit board is drawn. Considering the problem of convenient maintenance and upgrade replacement in the future, the MCU control part and other electronic components closely related to the MCU are drawn into a circuit module on the printed circuit board, which also includes other electronic components closely related to the MCU. Connect the other pins of the MCU to the pin header so that the module has an interface that can be connected to external circuits.

Fig. 1 is a structural connection diagram of the circuit of the present invention. Each module of the circuit includes: system reset circuit, battery power acquisition circuit, temperature and humidity sensor circuit, USB charging circuit, 3.3V voltage regulator circuit, 5V voltage regulator circuit, LED display circuit, CO concentration acquisition module interface, LCD screen interface, and lithium battery battery and other interface circuits.

The reset circuit is connected with the MCU, thereby resetting the entire circuit system.

The battery power acquisition circuit is connected to the MCU and the positive pole of the battery. The battery power acquisition circuit has an enable terminal, which is controlled by the MCU. When the control terminal of the MCU is at a high level, the battery power acquisition circuit is enabled so that it can collect the voltage of the battery. After the resistor divides the voltage, it is input to the port of the MCU. The MCU has a built-in AD converter, which can read the value of the voltage, and after calculation, get the current power of the battery.

The sensor circuit is a temperature and humidity sensor. The temperature and humidity sensor uses a low-power SHT10. The sensor has two lines connected to the MCU, which are the DATA data line and the SCK clock line. Under the control of the MCU, according to the data sheet of the sensor, read the temperature and humidity values according to the corresponding timing, and transmit them to the MCU through the DATA data line.

One end of the USB charging control circuit is connected to the USB interface, and the other end is connected to the charging selection switch. Select a low-power charging chip, refer to the chip data sheet, adjust the resistance of the programmable port, and match the appropriate capacitor, so that it can charge a single lithium battery. .

The 3.3V voltage regulator circuit is connected to the lithium battery through a switch, and the switch controls the connection between the battery and the voltage regulator circuit. When the switch is turned on, the power supply LED indicator lights up, indicating that the voltage regulator circuit is connected to the lithium battery and starts to work. It can stably output 3.3V voltage to provide stable power supply for MCU, temperature and humidity sensor, and LCD display.

The 5V voltage regulator circuit provides a stable 5V voltage supply by means of DC-DC boost and then LDO step-down. The DC-DC boost chip adopts a low-power chip, which has the characteristics of low power consumption, large input range, and programmable output voltage. Design the resistance value of the programmable resistor so that the output voltage is around 5.2V to 5.3V. The output of the DC-DC boost circuit is connected to a low-power LDO chip, which can output a stable and accurate 5V voltage to supply power for the gas sensor.

The LED display circuit provides LED display functions of various states. The negative poles of the four LED lights are connected to different ports of the MCU, so that the displayed information can be programmed and expanded, and can provide a concentration alarm function and indicate whether the system is working normally.

The interface circuit of the CO concentration acquisition module is designed according to the characteristics of the CO concentration acquisition module, and provides 3.3V and 5V power supplies to the CO concentration acquisition module. The high-precision CO sensor used in the CO concentration acquisition module can reach the ppb level. This interface circuit is designed with a UART interface for this series of CO concentration acquisition modules, and the data collected by the CO concentration acquisition module is sent to the MCU control module of the circuit board through the UART interface.

The LCD screen interface is the interface between the LCD display module and the circuit board, which is convenient for upgrading or replacing, and supplies power to the module and transmits data through this interface.

Lithium battery and other interface circuits include JTAG debug interface, external UART interface, and lithium battery interface. It makes it easy to connect other components of the circuit to the circuit board, which is convenient for future debugging and system maintenance.

Fig. 2 is a schematic circuit diagram of the CO concentration acquisition module of the present invention. The CO concentration acquisition module circuit includes an MCU control unit, a CO sensor filter voltage divider circuit, a JTAG debugging interface, and a circuit board connection interface.

The MCU control unit 1 of the CO concentration acquisition module is composed of an MCU, a crystal oscillator, and a filter capacitor, and the circuit board provides a 3.3V power supply and a reset signal, thus providing the minimum circuit system for the basic operation of the MCU.

The filter voltage divider circuit of the CO sensor consists of a slot, a filter capacitor and a voltage divider resistor. One end of it is connected to the sensor and the other end is connected to the MCU. The data transmitted by the sensor is filtered and processed by voltage division, and then transmitted to the MCU. Since the high-precision sensor has high requirements on the anti-interference ability of the system, the interface circuit is designed to complete the filtering and voltage dividing functions. The interface has a 5V power line, which comes from the power supply circuit of the circuit board to supply power for the CO sensor.

The JTAG debugging interface is connected with the MCU, which provides the program download, upgrade maintenance and debugging functions for the module.

The main board interface provides 3.3V power supply, 5V power supply, control signal, reset signal and UART connection line from the main board. Connect with MCU and filter voltage divider circuit. Through this interface, the circuit board can provide the necessary power supply and reset signal for the module, as well as the control signal of the circuit board for the module. Under the control of the circuit board, it can communicate with the module through the UART interface.

Claims (1)

1. the hand-held monitoring device of high accuracy open air CO concentration, it is characterised in that：The equipment includes device housings body, circuit main board； The circuit main board includes power switch, UART interface, USB charging inlets, lithium battery, LCD display module, the collection of CO concentration Module, Temperature Humidity Sensor；

The circuit main board of equipment is fixed in device housings body, and the device housings body is a regular cuboid；Device housings body The centre of the circuit main board front face of inner upper is fixed with LCD display；It is sequentially provided with the left of shell body internal circuit mainboard Power switch, UART interface, USB charging inlets；Fixed CO concentration acquisition modules on the right side of the circuit board of shell body inner upper；Outside The bottom of enclosure interior circuit main board is provided with lithium battery fixing device；

It is most of that the monitoring terminal of monitoring device includes four：Power management section, MCU system control section, data acquisition transmission Partly, LCD display portions；Wherein LCD display portions are made up of TFT LCD and LCD backlight drive circuit；Power management section by Charge management circuit, power supply management circuit and battery voltage supervisory circuit composition；Data acquisition hop is gathered by CO concentration Module, Temperature Humidity Sensor, UART interface composition；Systems control division point is made up of MCU, reset, debugging interface；

This equipment, as the storage of electric energy and supply core, using MCU as control core, can pass through USB using single lithium battery Charging, is powered, system power supply is powered from chargeable lithium cell by power supply switch control system；This equipment is by single-lithium-battery Pond output is connected with power management section, it is therefore an objective to be MCU, LCD display, CO sensor assemblies and other each circuit portions The available high-quality of offer is divided to power；Power reguirements are met, under control section MCU regulation and control so that CO sensor sensings To the information of under test gas gathered, read, transmitted and shown；

The each unit module for realizing whole system function is respectively：MCU control unit, system reset unit, battery electric quantity collection Unit, CO concentration acquisition modules unit, Temperature Humidity Sensor unit, Charge Management unit, power management unit and LCD display Unit；Wherein, MCU control unit is connected with other units so that whole equipment co-ordination, gathered data, and makes LCD display interfaces can be shown：Monitor CO concentration, ambient temperature and humidity, current battery level, battery dump energy percentage；

Wherein, MCU control unit includes MCU chip, MCU external circuitses, UART interface circuit and status indicator LED lamp；

System reset unit includes system reset button, reset resistor, reset capacitance；

Battery electric quantity collecting unit includes electric quantity acquisition and enables circuit and cell voltage bleeder circuit；

Sensor unit includes Temperature Humidity Sensor circuit and CO concentration acquisition module circuits；

Charging control unit includes USB interface and USB charge management circuits；

Supply control unit includes DC-DC booster circuit, 3.3V LDO decompression voltage regulators, 5V LDO lowering and stabilizing blood pressures electricity successively Road；

LCD display unit includes TFT LCD and LCD backlight drive circuit, LCD backlight drive circuit driving TFT LCD；

Wherein, MCU connect respectively 3.3V mu balanced circuits, Temperature Humidity Sensor, LED show, debugging interface, UART interface, reset Circuit, lcd screen interface, CO sensor module interfaces and battery voltage detection circuit, and battery voltage detection circuit according to It is secondary to be connected with lithium battery and USB charging circuits；5V mu balanced circuits are connected between lithium battery and CO sensor module interfaces； 3.3V mu balanced circuits are connected with lithium battery again；Temperature Humidity Sensor, LED are shown and lcd screen interface is again steady with 3.3V respectively Volt circuit is connected.