Abstract: This paper introduces an embedded industrial diagnostic system based on Bluetooth technology. This system can collect terminal monitoring information in real time and transmit it back to the central control center, realizing remote alarm and data acquisition and analysis functions. The paper provides a basic analysis of the real-time performance and stability of Bluetooth technology in industrial environments. It also attempts to explore a platform-independent control system to increase system independence and cross-platform operation. Finally , the paper discusses the combination of Bluetooth technology and the TCP/IP protocol stack, and the implementation and management of an embedded distributed database. Keywords: Bluetooth technology; Embedded system; Industrial diagnostic system Bluetooth technology provides point-to-point and point-to-multipoint wireless links based on the concept of a network, enabling people to exchange and transmit data information anytime and anywhere. With the widespread adoption of various Bluetooth terminal devices, new challenges have arisen regarding increasing the interoperability of Bluetooth devices, connecting them to the Internet, and the distributed storage of data from Bluetooth devices themselves versus centralized storage in the main control center. This paper introduces an embedded industrial diagnostic system using Bluetooth technology, capable of real-time acquisition of monitoring information (temperature, voltage, etc.) from terminals and transmission back to the central control center, realizing remote alarm and data acquisition functions. A basic analysis of the real-time performance and stability of Bluetooth technology in industrial environments is presented. Simultaneously, an attempt is made to explore a platform-independent control system to increase system independence and cross-platform operation. Finally, the paper discusses the integration of Bluetooth technology and the TCP/IP protocol stack, and the implementation and management of the embedded distributed database. This industrial diagnostic system features Bluetooth wireless communication capabilities, enabling multi-channel acquisition, real-time display of 24-hour industrial environment information storage, statistical analysis and diagnosis of acquired parameters, and monitoring and alarm functions. Administrators can manage data from each monitoring node from the central control center and remotely control and modify alarm parameters, alarm times, detection frequencies, etc. The system uses the LPC2106 chip with a 16/32-bit RISC ARM7DMI core and the Connectblue Cb-OEMSPA13i Bluetooth module as the main control processor module and Bluetooth communication module. 1. Bluetooth Technology Bluetooth technology is a short-range wireless communication technology standard jointly developed in May 1998 by five companies: Ericsson, IBM, Intel, Nokia, and Toshiba. It is an open, global industry standard. Its essence is to establish a universal radio air interface for communication between fixed or mobile devices, further combining communication technology with computer technology to provide a low-cost, low-power, cable-free wireless data and voice link, enabling devices to communicate or operate each other within a short range. This technology employs a frequency-hopping mechanism for data transmission, significantly improving its anti-interference performance. Operating in the globally available 2.4GHz ISM (Industrial, Scientific, and Medical) band, it boasts a transmission rate of 1Mbps and a transmission distance of 10m-100m. It can form a piconet consisting of up to eight devices, or a distributed network (Scatternet) composed of multiple independent, asynchronous piconet topologies. The channel can be encrypted using 0-bit, 40-bit, or 60-bit keys. The Bluetooth SIG has already established the international standard for the Bluetooth 1.2 system. The Bluetooth protocol stack for this system is shown in Figure 1. Bluetooth technology is widely used in PANs (Personal Area Networks), with familiar applications including wireless audio, as exemplified by ubiquitous Bluetooth earbuds. However, its application in industrial monitoring is rapidly expanding. While this is an early stage of exploration and research, it holds great promise. Many large European companies are launching their related solutions. [align=center]Figure 1 Bluetooth Protocol Stack[/align] 2 Chip Overview 2.1 Main Control Processor LPC2106 The LPC2106 is a Philips ARM7 DMI-S microprocessor with real-time emulation and tracing capabilities, embedded with 128KB of high-speed Flash memory. It employs a three-stage pipeline technology, with instruction fetching, decoding, and execution occurring simultaneously, enabling parallel instruction processing and improving CPU speed. Due to its very small size and extremely low power consumption, it is ideal for applications where miniaturization is a primary requirement. Multiple 32-bit timers, PWM outputs, and 32 GPICs make it particularly suitable for industrial control and small robotic systems. The absolute market share of the ARM core in embedded applications undoubtedly makes it the preferred solution for many industrial systems. This low-cost ARM7 chip from PHILIPS contains far more on-chip resources than the 51 microcontroller. In many industrial control fields that do not require audio and video processing, it is gradually replacing the 51 microcontroller and becoming the future trend. The LPC28xx model, which integrates network functionality and an LCD display driver module, and the low-cost LPC210X, became the best choices for our project design. [align=center] Figure 2 System Structure Diagram[/align] 2.2 Bluetooth Module Cb-OEMSPA13i The Cb-OEMSPA13i Bluetooth module is a Bluetooth serial adapter integrated by ConnectBlue, featuring RF transceiver, baseband control and management, and conforming to the RS232 interface protocol. Core operating voltage is 3-6V. The chip's hardware and firmware conform to the Bluetooth specification V1.1. RF transmit power supports CLASS2. Output frequency is 2.402 – 2.480 GHz, with a maximum receive frequency of +14dBm. Multi-point transmission is supported. Based on ConnectBlue's strong industrial application background, this module has been widely used in harsh industrial environments, and many improvements and enhancements have been made to both hardware and software for industrial environments, which is why we chose this module. 3. System Working Principle and Overall Design The system's principle block diagram is shown in Figure 2. Its working principle is as follows: The system acquires signals from point ①, including two analog signals, two digital signals, and two ambient temperature signals detected by a temperature sensor (PT100). These signals are sent to their respective signal acquisition and adjustment modules, which amplify and filter them according to their characteristics and requirements, adjusting the signal amplification to a certain amplitude. The signal acquisition and adjustment process is shown in Figure 3. The signals are then converted from analog to digital signals by a 10-bit A/D converter within the main control processor. The main control processor module runs an embedded operating system and on-chip signal analysis application software to analyze and process the data, perform threshold comparisons, and generate alarms. Simultaneously, the measurement and analysis results of each parameter and alarm information are displayed on the user interface. The FLASH ROM module compresses and stores the data, storing important data in E2PROM (database ② stores the threshold information, alarm information, and real-time data displayed for each parameter set on the user interface). The PPP protocol uses two circular queues, and the data is sent to the server in real time via the Bluetooth wireless transmission module to generate a more detailed test report, providing technical personnel with on-site information for evaluation. In addition, the administrator can manage the data of each monitoring node through the web on the server side, and remotely control the alarm parameters, alarm time, detection frequency and other settings of the device. 4 Hardware Circuit The hardware circuit includes a signal acquisition and adjustment module, an LPC2106 main control processor module with ARM7DMI as the core, a Connectblue Cb-OEMSPA13i Bluetooth module as the Bluetooth wireless network module, a power management and reset module and other protection and adjustment circuits. Each module specifically implements the following functions: (1) The input signal acquisition and adjustment module realizes the acquisition of multiple signals, filters and suppresses interference signals such as low frequency, high frequency and power frequency, and amplifies, zero-point adjusts and full-scale adjusts analog quantities. [align=center] Figure 3 Signal acquisition and adjustment module[/align] (2) The main control processor module combines a commercial embedded operating system and on-chip sampling analysis software to realize the A/D analog-to-digital conversion and control of analog signals, digital filtering and wavelet analysis, data calculation and analysis, and control and manage each module of the hardware part at the same time. (3) The storage module realizes the real-time storage of various signal data and can store alarms generated in real time at the same time. E2PROM has erasable and writable functions, and the stored data will not be lost even if the system power is turned off. (4) The wireless network module realizes wireless data transmission and Bluetooth wireless network service. It connects with the Bluetooth wireless port on the PC or other devices to realize the piconet in Bluetooth technology, and allows multiple Bluetooth interface devices to form a peer-to-peer Bluetooth wireless network. (5) The power management and reset module is mainly responsible for providing stable voltage to the system and detecting the operating status of the system to ensure the fault-free operation of the system. (6) A large number of filtering components and circuits are used, and a four-layer board design is adopted to minimize external interference and system instability factors. (7) Since the Bluetooth module involves high frequency, a floating connection plug is designed separately for it in the hardware circuit so that it is not affected by interference from other modules. At the same time, an interface for an external antenna and an interface for debugging and resetting are reserved for the Bluetooth module to increase the system's debuggability and expandability. 5 Software Design 5.1 Software Hierarchy [align=center] Figure 4 Software Hierarchy Diagram[/align] 5.2 Software Program Implementation 5.2.1 Operating System This system uses Infrabed, a commercial embedded operating system developed by Embedded Artists in Sweden. Infrabed is a highly configurable operating system. It can select and remove low-level framework components of the embedded system according to user needs to achieve optimal and most intensive system configuration. In the implementation of this system, we adopted five modules: preemptive real-time operating system, PPP, TCP/IP communication protocol, file system, and Web server. 5.2.2 Communication Protocol The core of Bluetooth is the protocol stack. The Bluetooth protocol stack allows multiple devices to locate, connect, and exchange data with each other, and enables interoperability and interactive applications. The protocol stack runs on the Bluetooth module and the microprocessor respectively. It is the embedded software that manages system resources, controls hardware, processes commands from the host through HCI, and completes Bluetooth functions. The Bluetooth module implements a subset of the Bluetooth protocol, LAN Access Point (LAP). This application mode uses the IETF's Point-to-Point Protocol (PPP) on Bluetooth connections. PPP is a widely used Internet standard that provides host configuration and preparation for IP communication. PPP is designed for simple links that transmit data packets between peer units. This link provides full-duplex operation and delivers data packets sequentially. PPP provides a common solution for simple connections based on various hosts, bridges, and routers. In the system implementation, we ported the TCP/IP protocol to the Bluetooth link, enabling the application layer to transparently operate the highly general socket interface, facilitating future application expansion and porting. In addition to the underlying communication protocol, we also designed our own protocol specifically for transmitting alarm, sampling information, and database synchronization. This protocol provides a unified format for the interconnection of new Bluetooth devices in the future. 5.2.3 Distributed and Centralized Database System The locally distributed database implemented through FLASH memory is only used as a temporary data storage location due to the limited FLASH space. The centralized database on the host computer is the system's main data center. In terms of database implementation, the system added interface functions for dedicated operations such as adding, querying, and deleting alarm and sampling information to improve database usability and operational efficiency. To ensure synchronization between different databases, the protocol and data format were modified, and fields such as timestamps and synchronization times were added to guarantee data synchronization between the two sides. To prevent system crashes, power outages, and other extreme situations, the system performs local FLASH backups of the latest data. This dual backup of the latest data increases data security. User configuration information is also backed up and synchronized between the two sides for system recovery. 5.2.4 User Interface The user interface design process considered two requirements: first, the need for platform independence, requiring the central control interface to run on different devices; and second, the need for real-time performance, as real-time performance is undoubtedly a crucial consideration due to the specific requirements of industrial applications. Finally, we adopted two technologies to increase customer choice: 1. Embedded CGI + WebServer. This provides excellent platform independence; the system can be monitored and controlled on any device that can run an IE browser. 2. Using Sun's Java applet technology for the user interface. Applet technology is widely used due to its good platform independence, and it also has excellent real-time performance, which is not possible with option 1. However, the only requirement is that the device must support both IE browsers and a Java interpreter. With these two technologies, the system can run on all PCs, most PDAs, and mobile phones without installing any software, greatly facilitating operators. 6. Conclusion To overcome the shortcomings of traditional industrial control machines, such as numerous accessories, wired detection and transmission methods, inconvenient networking, limited detection parameters, and poor expandability and interactivity, this system provides an embedded industrial diagnostic system with Bluetooth wireless communication. This industrial diagnostic system features Bluetooth wireless communication capabilities, enabling multi-channel acquisition, real-time display and storage of industrial environment information, parameter statistical analysis and diagnosis, and monitoring and alarm functions. Simultaneously, it allows remote control of equipment alarm parameters, alarm time, detection frequency, and other settings. It includes an embedded operating system and data analysis and diagnostic application software, facilitating the expansion of equipment functionality. References: [1] Karim Yghmour, Building Embedded Linux Systems. O'Reilly, 2003 [2] Ma Jiancang, Luo Yajun, et al. Bluetooth Core Technology and Applications, Beijing: Science Press, 2003 [3] Feng Qingsheng, Li Hong, Ji Yonggang, Building a Wireless Home Network Based on Bluetooth Technology. Microcomputer Information, 2006, No. 3-2