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Design of a Wireless Constant Temperature Box System Based onNRF24L01 Module
Abstract
Temperature plays a very important role in people’s daily lives, and people not only pay attention to the changes in daily environmental temperature, but also in many industrial fields such as industry, medicine, military, and many aspects of life, temperature measurement devices are needed. Traditional wired measurement circuits are complex, easily interfered with, and not very accurate, which does not meet the requirements of certain harsh industrial environments and some outdoor environments. Therefore, choosing a good performance digital temperature sensor and wireless transmission module is particularly important. In modern industrial control, considering power consumption is also an important parameter, this system uses a low-power high-performance microcontrollerSTC89C52RC andDS18B20 temperature sensor, and usesnRF24L01 wireless module for short-distance temperature monitoring.
The design usesSTC89C52RC which is simple and practical, and operates the same asMCS-51. The wireless data communication transceiver chipNRF24L01 is a low-cost wireless transceiver that operates at2.4〜2.5GHz with very low power consumption. Additionally, the temperature sensorDS18B20 has advantages such as small size, low cost, and high accuracy. Real-time temperature measurement and display, corresponding relay operation when exceeding temperature limits, and the upper and lower limit temperatures can be set via buttons, among other functions.
This system has low power consumption, low cost, and simple hardware circuits, making it a feasible design solution for wireless temperature measurement.
Keywords：NRF24L01；Temperature SensorDS18B20；STC89C52RCTemperature Control Constant Temperature Box
Table of Contents
Chapter 1 Introduction…………………………………….. 1
1.1 Background and Significance of the Topic…………………………….. 1
1.2 Research Status at Home and Abroad and Existing Research Achievements in Related Fields……….. 1
1.3 Analysis of Design Tasks…………………………….. 1
1.4 Expected Results…………………………………. 2
Chapter 2 Overall Scheme Design Verification………………………… 2
2.1 System Scheme Design………………………………… 2
2.2 Module Scheme Design………………………………… 3
2.2.1 Main Control Chip Scheme………………………………. 3
2.2.2 Wireless Communication Module Scheme…………………………… 4
2.2.3 Temperature Sensing Scheme………………………………. 4
2.2.4 Display Module Scheme………………………………. 5
Chapter 3 System Module Design……………………………… 5
3.1 STC89C52RC Main Control Module Design………………………. 5
3.2 nRF24L01 Wireless Module Design……………………….. 7
3.2.1 Overview of nRF24L01…………………………….. 7
3.2.2 Pin Functions and Descriptions……………………………. 8
3.2.3 Operating Modes………………………………….. 9
3.2.4 Configuration Words…………………………………… 10
3.2.5 Module Circuit Diagram and Application Principle Block Diagram…………………… 10
3.3 Display Circuit Module Design……………………………. 12
3.3.1 Basic Structure of LCD 1602 Display………………….. 12
3.3.2 Working Principle of LCD 1602 Display………………….. 12
3.4 Temperature Sensor Module Design………………………….. 13
3.4.1 Pin Configuration and Internal Structure of DS18B20……………….. 13
3.4.2 Working Principle of DS18B20………………………… 14
3.4.3 Hardware Design of DS18B20………………………… 15
Chapter 4 Software System Design…………………………… 15
4.1 Software Design of Each Module…………………………….. 15
4.1.1 Software Design of Display Module………………………….. 15
4.1.2 Temperature Detection…………………………………. 16
4.1.3 Software Design of Wireless Transmitting Module………………………. 17
4.1.4 Software Design of Wireless Receiving Module………………………. 18
4.2 Overall Software Design……………………………… 19
4.2.1 Sending Part…………………………………. 19
4.2.2 Receiving Part…………………………………. 20
4.3 Summary of This Chapter…………………………………… 21
Chapter 5 System Debugging and Experimental Results……………………… 21
5.1 Debugging Steps…………………………………… 21
5.2 Experimental Results…………………………………… 21
5.3 Summary of This Chapter…………………………………… 23
Conclusion……………………………………………… 23
Acknowledgments…………………………………………. 25
References……………………………………. 25
Chapter 1 Introduction
1.1 Background and Significance of the Topic
In today’s modern life, collecting temperature through wireless communication has become increasingly common. As the production of agriculture and industry demands higher requirements for temperature and humidity, accurate temperature measurement has become very important. Temperature cannot be simply obtained like mass and length; it can only be measured indirectly through other related properties. Now, temperature measurement can be done using temperature sensors, which simply convert the temperature value into electrical signals or other signals through sensors, and after relevant processing, convert it into a temperature display. Temperature measurement devices generally consist of temperature sensors and signal processing circuits. In some cases, when the monitoring range is large, wiring is inconvenient and not conducive to later maintenance, we use wireless modules to collect temperature.
A multi-channel wireless temperature measurement system is widely used in various fields of temperature measurement engineering, such as temperature detection systems in urban hospitals, heating system detection in residential areas, temperature control in vegetable greenhouses, and temperature protection in industrial production. Considering the demand for monitoring multiple temperature points in many agricultural and industrial environments, it is generally necessary to measure dozens of points or more. Therefore, this paper designs a multi-channel wireless temperature monitoring system.
1.2Research Status at Home and Abroad and Existing Research Achievements in Related Fields
In the 2.4GHz frequency band, there are already various standard wireless protocols that have long transmission distances and strong anti-interference capabilities. Therefore, we must ensure sufficient anti-interference and maintain data continuity in the 2.4GHz frequency band.
The nRF24L01 can easily build a wireless network due to the ANT protocol. The ANT wireless personal area network communication technology maintains data integrity and has the advantages of low power consumption and low cost. The nRF24L01 is a wireless communication chip that uses FSK modulation, allowing point-to-point and 1-to-n high-speed communication. The MCU only needs to provide 5 general pins and one interrupt pin to achieve communication functionality. Therefore, building a wireless communication function using the nRF24L01 in the MCU system is very simple.
With the development of electronic technology, the accuracy of temperature sensors is getting higher, anti-interference capability is improving, and their size is becoming smaller.
1.3Analysis of Design Tasks
This system design uses the nRF24L01 wireless communication module, with the STC89C52RC as the core to control short-distance wireless temperature transmission. This system design has advantages such as low cost, fast transmission, simple software design, low power consumption, and high reliability. The entire design connects the host and slave through the NRF24L01 wireless module. The slave uses the microcontroller STC89C52 as the core, and transmits the temperature collected by the temperature sensor to the host through the wireless module nRF24L01. The host receives the temperature data through the wireless module nRF24L01 and then displays it on the LCD1602, thus achieving the purpose of monitoring.
This design uses the STC89C52RC microcontroller. The microcontroller has the following characteristics:
· Simple system structure, high reliability.
· Strong processing capability, fast speed.
· Low voltage, low power consumption, small size.
· Most functions are implemented by software programming, with high reusability and cost-effectiveness.
1.4 Expected Results
Two slaves can send the temperature data received from the temperature sensors to the host through the wireless module within a range of 5m. The host receives the data through the wireless module and displays it on the LCD1602, thus achieving the purpose of monitoring the temperature at various points. It can also automatically control the relay operation for heating and cooling based on the set upper and lower limits.
Chapter 2 Overall Scheme Design Verification
2.1 System Scheme Design
The slave:
The transmitter consists of the STC89C52RC microcontroller, nRF24L01 wireless module, and DS18B20 temperature module.
Figure 2-1
The host:
The receiver consists of the STC89C52RC microcontroller, LCD1602 display module, relay module, and nRF24L01 wireless module.
Figure 2-2
2.2 Module Scheme Design
2.2.1 Main Control Chip Scheme
Scheme 1: Use STC89C52RC to implement. The microcontroller software programming can easily achieve most functions, has a high degree of freedom, clear structure, is easy to debug and maintain, and has strong readability and portability. It has advantages such as small size and simple hardware setup. This system consists of one host and two slaves for multi-channel temperature data collection through a two-level distributed temperature measurement. Additionally, the application of STC89C52RC is already very widespread, and the use of related technologies is very proficient, making development easy.
Scheme 2: Use MSP430F149 microcontroller. This microcontroller has low power consumption and integrates a high-speed 12-bit ADC, making it powerful. However, this design is simple and does not require such a powerful microcontroller as MSP430F149, and the cost of MSP430F149 is high, as it is in TPFQ package, which requires PCB manufacturing, increasing the development cycle.
Considering all factors, we choose STC89C52RC as the MCU for this system.
2.2.2 Wireless Communication Module Scheme
Scheme 1: Use GSM communication module. GSM can transmit data over long distances using satellite communication or mobile phone cards, but the communication process incurs charges, making both upfront and ongoing costs relatively high.
Scheme 2: Use TI CC2430 communication module. Although this module has fast communication speed, it is costly and complex to operate.
Scheme 3: Use nRF24L01 communication module. This module has advantages such as high speed, low power consumption, and small size. It can transmit several kilometers (PA), but is cheaper, uses SPI bus communication, and has simple circuits and easy operation.
Therefore, considering all factors, we adopt Scheme 3 as the communication module for this system.
2.2.3 Temperature Sensing Scheme
Scheme 1: Use a thermistor. Thermistors have a wide working temperature range, small size, practicality, and ease of mass production, but their sensitivity is average, and reliability is poor, only able to detect temperature changes of 6-10°C. Additionally, using temperature sensors like AD590 requires AD conversion before sending to the MCU, complicating the structure of the temperature measurement device. This method also has a complex algorithm, which increases the difficulty of software implementation, leading to increased design costs and extended design cycles.
Scheme 2: Use temperature sensor DS18B20. Since DS18B20 outputs digital signals, it is easy for the MCU to process and control, eliminating many peripheral circuits of traditional measurement methods. The physical and chemical properties of the sensor are very stable, making it suitable as an industrial temperature sensor, with better linearity. Within the range of 0 ~ 100 degrees Celsius, the maximum linear error is less than 1 degree Celsius. The single-bus data transmission of DS18B20 improves signal stability and accuracy. Using the DS18B20 digital temperature sensor for temperature measurement has advantages such as simple circuit setup, small size, and easy programming. Therefore, using digital integrated chips will become the trend in circuit development.
Considering the above, we choose DS18B20.
2.2.4 Display Module Scheme
Scheme 1: Use LED digital tube display. LED digital tubes have advantages such as simple hardware circuits, easy debugging, and relatively easy software implementation, but they occupy many IO ports and cannot display characters.
Scheme 2: Use LCD1602 display. LCD1602 displays rich content, responds quickly, and is also cost-effective, with proficient programming technology.
Considering the above schemes, we choose LCD1602.
2.2.5 Load Driving Module Scheme
Scheme 1: Use bidirectional thyristor to control the load. Thyristors have a long lifespan and no noise when closed, but the circuit is relatively loaded, and the failure rate of the circuit will also increase, and the load requirements are high, unable to drive too large a load.
Scheme 2: Use relays to drive loads. The design uses a 5V relay, which can drive a maximum load of 250V10A, and can connect any load within the power range, with a simple driving circuit and low failure rate.
Considering the above schemes, we choose to use relays to drive loads.
Chapter 3 System Module Design
3.1 STC89C52RCMain Control Module Design
STC89C52RC is a low-voltage, high-performance 8-bit microcontroller, with 8k Flash memory, 512 bytes of RAM, compatible with the standard MCS-51 instruction set, and built-in 8-bit general-purpose CPU and 2K bytes of EEPROM storage space.
Main features include:
1) 8k rewritable Flash ROM;
2) 32 bidirectional I/O ports;
3) 512x8bit internal RAM;
4) Can be directly downloaded via serial port;
5) Built-in 2K bytes of EEPROM storage space;
Pin diagram see Figure 3-1
Figure 3-1 Microcontroller Pin Diagram
The microcontroller control module consists of the minimum system of STC89C52RC, which includes the microcontroller, crystal oscillator circuit, and reset circuit. The crystal oscillator circuit consists of two 22pf capacitors connected to pins 18 and 19 and a 12MHz crystal oscillator. The minimum system is shown in Figure 3-2
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Figure 3-2 Minimum System of Microcontroller
3.2nRF24L01Wireless Module Design
3.2.1Overview of nRF24L01
NRF24L01 is a new type of single-chip RF transceiver device, operating in the 2.4 GHz~2.5 GHz frequency ISM band. It integrates a frequency generator, enhanced “SchockBurst” mode controller, power amplifier, crystal oscillator, modulator, and demodulator, with output power that can be easily configured by software.
NRF24L01 has various low-power modes (power-down mode and idle mode) for easier energy-saving design. The main features of nRF24L01 are:
1. Automatically generates headers and CRC checksums on-chip;
2. GFSK modulation, hardware integration of OSI link layer;
3. SPI rate of 0 Mb/s to 10 Mb/s;
4. 125 channels compatible with other nRF24 series RF devices;
5. Automatic acknowledgment and retransmission functions;
6. Data transmission rates of 1 Mb/s or 2 Mb/s;
7. Supply voltage of 1.9 V to 3.6 V;
3.2.2Pin Functions and Descriptions
The circuit diagram of nRF24L01 pin is shown in Figure 3-3.
Figure 3-3
Due to the high-frequency circuit design, the placement of components and the wiring methods have high requirements, so we directly use the current finished module, thus avoiding the design issues of high-frequency circuits. Figure 3-4 shows the PCB diagram and physical diagram of nRF24L01.
Figure 3-4
The following Figure 3-5 shows the functions of each pin of the module:
Figure 3-5
3.2.3Operating Modes
By configuring the registers, nRF24L01 can be set to transmit, receive, idle, and power-down modes, as shown in Figure 3-6.
Figure 3-6 nRF24L01 Operating Modes
3.2.4Configuration Words
SPI port synchronous serial communication interface, during transmission, bytes are first transmitted, followed by high-order bytes, and it has a high transmission rate.
nRF24L01 has a total of 25 configuration registers, with commonly used configuration registers shown in Figure 3-7.
Figure 3-7 Commonly Used Configuration Registers
3.2.5Module Circuit Diagram and Application Principle Block Diagram
The circuit diagram of the nRF24L01 wireless module is shown in Figure 3-8:
Figure 3-8 Module Circuit Diagram
Figure 3-9 shows the part of the nRF24L01 wireless module that needs to be connected to the MCU:
Figure 3-9
3.3Display Circuit Module Design
3.3.1Basic Structure of LCD 1602 Display
1602 uses a standard 16-pin interface, as shown in Figure 3-10, where:
Pin 1: GND is the power ground.
Pin 2: VCC connects to the positive terminal of the 5V power supply.
Pin 3: V0 is the contrast adjustment terminal of the LCD, and the contrast is inversely proportional to the voltage.
Pin 4: RS is the register select, selecting the data register when high, and the instruction register when low.
Pin 5: RW is the read/write signal line, performing read operations when high and write operations when low.
Pin 6: EN is the enable pin, reading information when high, and executing instructions on negative edge.
Pins 7 to 14: 8-bit data lines for bidirectional communication with the microcontroller.
Pins 15 to 16: Empty pins or backlight power supply. Pin 15 is the positive terminal of the backlight, and pin 16 is the negative terminal of the backlight.
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Figure 3-10
3.3.2Working Principle of LCD 1602 Display
LCD1602 has stored 160 different character dot matrix graphics in its memory, each character corresponding to a fixed code, for example, the code for the letter “A” is 01000001B (41H). When displaying, the module shows the dot matrix character graphic stored in address 41H, allowing us to see the letter “A”.
In microcontroller programming, character constants or variables can also be assigned, such as ‘A’. Since the CGROM storage code is basically the same as the character codes on our computer, we can write character codes into DDRAM in C51, and even directly with P1 = ‘A’.
3.4Temperature Sensor Module Design
The DS18B20 chip has advantages such as small size, low cost, strong anti-interference, high accuracy, and a unique single-wire interface. Each DS18B20 contains a unique serial number, allowing multiple DS18B20s to exist on a single bus. The peripheral hardware is simple, powered by the data bus, with a voltage range of 3.0 V to 5.5 V, and a temperature measurement range of -55°C to +125°C. The packaging of the DS18B20 chip is shown in Figure 3-11.
Figure 3-11
3.4.1Pin Configuration and Internal Structure of DS18B20
Pin definitions:
(1) DQ is the single data bus, which is the digital signal input/output terminal;
(2) GND is the power ground;
(3) VDD is the external power supply input terminal.
The internal structure is shown in the following figure:
Figure 3-12 Internal Structure of DS18B20
3.4.2Working Principle of DS18B20
The temperature detection and digital data output of DS18B20 are all integrated on a single chip, using a single-bus communication method with strong anti-interference capability.
The steps for measuring temperature using DS18B20 are: initialize DS18B20 → skip ROM operation command → start temperature conversion command → wait for conversion to complete → initialize → skip ROM operation command → read temperature register command, thus allowing the temperature data to be read.[4]
Figure 3-13
3.4.3Hardware Design of DS18B20
Figure 3-14 Hardware Connection Diagram of DS18B20
3.5Relay Driving Module Design
Electromagnetic relays generally consist of an iron core, coil, armature, contact spring, etc. As long as a certain voltage is applied across the coil, a certain current will flow through the coil, generating an electromagnetic effect, causing the armature to overcome the return spring’s pull and attract to the iron core, thus bringing the moving contact into contact with the static contact (normally open contact). When the coil is de-energized, the electromagnetic attraction disappears, and the armature returns to its original position due to the spring’s reaction force, releasing the moving contact from the original static contact (normally closed contact). This on-off action achieves the purpose of conducting and cutting off the circuit. For the relay’s “normally open and normally closed” contacts, the static contact that is in the off state when the relay coil is not energized is called the “normally open contact”; the static contact that is in the on state is called the “normally closed contact”. Relays generally have two circuits: a low-voltage control circuit and a high-voltage working circuit.
In the circuit, the relay is driven by a PNP transistor. When the threshold exceeds the set value, the microcontroller will switch from high to low, turning on the transistor to energize the relay, which acts as a switch to drive the load. The hardware circuit is shown in Figure 3-8.
Chapter 4 Software System Design
4.1 Software Design of Each Module
4.1.1 Software Design of Display Module
The flowchart is shown in Figure 4-1.
4-1 Software Flowchart of Display Module
4.1.2 Temperature Detection
The temperature detection software design follows the single-bus protocol, with the MCU writing and reading data from the DS18B20 through timing. The DS18B20 completes the operation through the following steps: reset, receive acknowledgment, read ROM serial number, start temperature conversion, wait for conversion to complete, and hold data.[7]
The flowchart is shown in Figure 4-2.
Figure 4-2 Temperature Detection Software Flowchart
4.1.3Software Design of Wireless Transmitting Module
First, initialize, then configure the nRF24L01 to enter transmit mode via the SPI bus. Then write the target address and data of the data to be transmitted into the wireless communication module’s buffer, and after a certain delay, transmit the data.[7]
The flowchart is shown in Figure 4-3.
Figure 4-3 Wireless Transmitting Software Flowchart
4.1.4Software Design of Wireless Receiving Module
When receiving data, first configure the wireless communication module to receive mode. Then wait for data; when the receiver detects a valid address and CRC, it stores the data packet in the receiving stack, while the interrupt flag RX—DR in the status register is set high, generating an interrupt that makes the IRQ pin go low to notify the microcontroller to fetch the data.[7]
The flowchart is shown in Figure 4-4.
Figure 4-4 Wireless Receiving Software Flowchart
4.2Overall Software Design
4.2.1 Sending Part
The overall idea of the sending part: initialize the temperature sensor, measure the temperature with DS18B20, then write the temperature value into the data to be transmitted, and then initialize the nRF24L01 wireless module to send the temperature to the host. The flowchart is shown in Figure 4-5.
Figure 4-5 Overall Flowchart of Sending Part
4.2.2Receiving Part
The receiving part first initializes the nRF24L01 wireless module, then checks for receiving interrupts. If data is read in and processed, it is displayed on the LCD1602. The flowchart is shown in Figure 4-6.
Figure 4-6 Overall Flowchart of Receiving Part
4.3Summary of This Chapter
This chapter mainly explains the system program and design ideas, and introduces the program flow of each module and the final flow, adopting a modular programming approach for the system software, thus allowing for the invocation of sub-module programs during software debugging, which is beneficial for sub-module debugging.
Chapter 5 System Debugging and Experimental Results
5.1 Debugging Steps
Step 1: Complete the soldering of the hardware circuit.
Step 2: First, burn a simple test program to check that the LCD1602 display works correctly.
Step 3: Connect the microcontroller of the receiving part to a digital tube and write the program to measure temperature. Test the DS18B20 related hardware and software.
Step 4: Build a simple wireless communication hardware, write a simple test sequence, and check the sending and receiving hardware modules.
Step 5: Combine all the sequences to build a complete hardware setup with one host and two slaves, checking whether the system can display the temperature values measured by the two slaves on the LCD1602 through wireless module communication.
5.2Experimental Results
After simple experiments, some experimental data were obtained, with specific results shown in Table 5-1:
Table 5-1 Data Test Table
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Test Data |
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Value |
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Transmitting End Current |
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2.7mA |
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Receiving End Current |
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10mA |
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Transmitting and Receiving Voltage |
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3.0V |
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Transmitting End Power |
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8.10mW |
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Receiving End Power |
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30.0mW |
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Transmission Distance |
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>5m |
From the table, it can be seen that the entire system has low power consumption, and the transmission distance has also reached the original design requirements.
Figure 5-1 shows the host of the wireless temperature measurement system, which initializes the LCD1602 immediately upon power-on and waits for data from the transmitting end to receive and display it in real-time on the LCD1602.
Figure 5-1 Transmitting Part Finished Product
Figure 5-2 shows the slave of the wireless temperature measurement system. Upon power-on, it immediately completes initialization and sends the temperature measured from the DS18B20 to the host via the wireless module.
Figure 5-2 Receiving Part Finished Product
5.3Summary of This Chapter
This chapter mainly introduces the hardware setup of the system, software debugging, and experimental results.
Software and hardware debugging used the sub-module testing method, ensuring that each module works normally before integration, reducing the debugging workload.
Finally, we conducted simple experiments on the temperature measurement system, which basically met the design requirements.
Conclusion
This design uses the STC89C52RC to collect and process data, collecting non-electrical signals through sensors. The system implements a digital thermometer wireless monitoring system using the direct digital input type temperature sensor DS18B20. This system design utilizes the advantages of DS18B20, such as high accuracy, strong anti-interference capability, simple circuit, and the ability to mount multiple sensors on a single bus. In contrast, traditional temperature detection systems use popular circuits to measure environmental temperature, which, although low in cost, have poor accuracy and reliability, and do not provide full digital output, requiring AD conversion circuits, which increases circuit complexity.
This design uses the NRF24L01 wireless communication module to achieve temperature monitoring, eliminating the hassle of traditional wiring, maintaining circuit simplicity, and facilitating the installation and maintenance of the entire system. However, this design also encountered some technical challenges, such as the programming and debugging of the wireless module nRF24L01.
However, through this design, my learning and understanding abilities have increased, and I have gained a certain understanding of wireless transmission.
Continuously browsing relevant materials online and in libraries, after two months of effort, this design has achieved the expected goals. The relevant work summary is as follows:
1. The focus of this design content:
(1) Debugging of the NRF24L01 wireless transmission module.
(2) Various operation commands of DS18B20.
(3) Microcontroller LCD display.
2. Research Outlook
With the development of technology, temperature monitoring systems are rapidly developing towards high precision, small size, multi-point, high reliability, and ease of installation and maintenance.
1. Improve the measurement accuracy and resolution of temperature controllers.
Traditional temperature measurement systems use thermistors with low accuracy, employing 8-bit A/D converters, resulting in complex circuits and low reliability and resolution. Currently, both domestic and international use high-precision and high-resolution intelligent temperature sensors, which have good reliability and safety, with a resolution generally reaching 0.5~0.0625°C.
2. Diversification of functions.
The testing functions of new intelligent temperature detection systems are continuously enhanced, and humidity monitoring can also be added to form a complete monitoring system. Additionally, internal integration of EEPROM chips can store user commands.
Acknowledgments
My four years of university are about to pass, and a beautiful tomorrow awaits us.
First, I would like to thank my advisor @#$ for their guidance. Although the teacher is usually very busy with classes and meetings, during the two months of our graduation design, they patiently helped us throughout the entire process, from collecting materials in the library and online to determining the initial plan, mid-term modifications, and final improvements. The teacher carefully corrected my mistakes in learning. Secondly, I would like to thank my classmates who worked on the graduation design with me; their companionship and suggestions have also greatly helped me, and they helped me solve some technical difficulties. I also want to thank all the teachers in the university, who not only taught us professional knowledge but also educated us on the principles of being a person.
Finally, I express my sincere gratitude to my classmates and teachers. Thank you!
References
[1] nRF24L01 Wireless Transceiver Module Development Guide [S] (V3.2)
[2] Zhou Yuanju, Wireless Temperature Monitoring System Based on AT89S52 and NRF24L01 [J]. 2012, Issue 2
[3] Guo Gang, Li Simin. Short-distance Wireless Data Transmission System Based on nRF24E1 [J]. Journal of Guilin University of Electronic Technology, 2004, 24 (3).
[4] Li Huicong. Discussion on Multi-point Temperature Measurement Method of DS18B20 [J]. Microcomputer Information, 2010(26).
[5] Ying Qing, Wang Daihua, Zhang Zhijie. Wireless Data Transmission System Based on nRF24L01 [J]. Modern Electronic Technology, 2008, 31 (7): 68-82.
[6] Ding Yonghong, Sun Yunqiang. Design of Wireless Data Transmission System Based on nRF2401 [J]. Foreign Electronic Measurement Technology, 2008, 27 (4): 45-47.
[7] Zhu Yuying, Cai Zhanhui. Design of Remote Temperature Detection System Based on NRF24L01 [J]. Communication and Information Processing, 2010, 29(5): 56-58.
[8] Pan Yong, Guan Xuekuai, Zhao Rui. Design of Intelligent Wireless Temperature Measurement System Based on NRF24L01 [J]. Electronic Measurement Technology, February 2010.
[9] Li Wenzhong, Duan Zhaoyu. Introduction and Practice of Short-distance Wireless Data Communication [M]. Beijing University of Aeronautics and Astronautics Press, 2006, 80~259.
[10] Yu Qianqian, Yu Bin. Detailed Explanation of Short-distance Wireless Communication: Based on Microcontroller Control [M]. Beijing: Beijing University of Aeronautics and Astronautics Press, 2009, 125~246.
[11] Data sheet for nRF2401 Single Chip 2.4G Transceiver. Nordic, 2003.
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