Abstract: This paper mainly studies a distributed motor control system based on the LF2407A DSP microcontroller chip and CAN bus. It elaborates on the characteristics of DSP industrial control chips, the principle and protocol of CAN bus, and provides a control example of the LF2404A microcontroller with CAN bus applied to a motor system. Keywords: LF2407A, CAN bus, CAN node Introduction CAN (Controller Area Network) is a local area network mainly used for monitoring and controlling various devices. Originally designed by Bosch in Germany for automotive monitoring systems, it has excellent functional characteristics and extremely high reliability, strong anti-interference capabilities, and a serial data communication bus. TI's 24X series chips feature excellent processing performance (30MIPS), high peripheral integration, large program memory capacity, and fast A/D conversion speed. They are DSP (Digital Signal Processing) chips designed for industrial control. The LF2407A, with its rich integrated peripherals, provides a digital control solution for motors. Its embedded CAN bus controller, based on the CAN 2.0B specification, provides CAN communication functionality, offering a solution for realizing distributed industrial monitoring local area networks. CAN Bus Introduction: CAN belongs to the fieldbus category, effectively supporting serial communication networks for distributed or real-time control. CAN has a wide range of applications, from high-speed networks to low-cost multi-channel connections. In applications such as automotive engine control components, sensors, and anti-skid systems in the field of automation electronics, CAN bit rates can reach up to 1Mbps. Unlike traditional control systems that use a one-to-one connection method based on control loops, fieldbus uses intelligent field devices with computation, control, and communication functions. It can complete data acquisition, data analysis, and control processing in the field, and send relevant data to the host and other field devices, achieving thoroughly distributed control. CAN Bus Characteristics: 1. System openness. 2. High autonomy and intelligence of field devices. 3. High system decentralization. 4. Strong adaptability to field environments. CAN Node Layered Structure : CAN Object Layer CAN Transfer Layer The physical layer (or object layer) is responsible for message filtering and status/message processing. The transport layer is the core of the CAN protocol. It provides received messages to the object layer and receives messages from the object layer. The physical layer defines the actual signal transmission method. Its role is to perform the actual transmission of bit information between different nodes based on all electrical attributes. Figure 1 shows the CAN node layered structure. LF2407A Introduction: DSP (Digital Signal Processing) processes signals digitally, including acquisition, transformation, filtering, estimation, enhancement, compression, and recognition, to obtain a signal form that meets user needs. The LF2407A is a new type of industrial control digital signal processing chip with the following features : 1) 32-bit CPU, 32-bit ALU, 16*16-bit parallel multiplier, 3 scaling shifters, 8 16-bit auxiliary registers; 544 words of on-chip data/program DARAM, 2K of SARAM, 32K of on-chip program FLASH, and 64K of data and memory addressing range; 2) Four-stage pipelined operation, eight-stage hardware stack, and five external interrupts; 3) Two event managers, EVA and EVB, including: 16 PWM channels, 10 compare CMP units, 4 16-bit general-purpose timer/counters, 6 capture units CAP, and 4 integral encoder pulse QEP units; 4) 16-channel 10-bit A/D conversion with a conversion time of 500ns and a maximum sampling rate of 1MHz; 5) 41 individually programmable multiplexed I/O pins; a phase-locked loop (PLL) based clock module; a watchdog timer module with real-time interrupt (WATCH_DOG); serial communication interface (SPI) and serial peripheral interface (SPI), and CAN communication module interface; 6) 33ns instruction cycle, 30 MIPS execution per second, system +3.3V power supply. The LF2407A embeds a CAN controller . The LF2407A chip integrates a 16-bit CAN control module, fully compatible with the CAN 2.0B protocol, supporting standard and extended formats. The LF2407A's CAN module consists of two main parts: the CAN control/status register and the CAN mailbox RAM area. Its block diagram is as follows: The CAN control/status register section contains 16 16-bit CAN control/status registers, namely the control register, status register, interrupt register, and receive mask register. It completes all the services and functions of the data link layer defined by the ISO/OSI model, including the object layer and transport layer. This system implements control frame structure, performs arbitration, error detection, error calibration, and fault determination. CAN Controller Interface — PCA82C250: The PCA82C250 is the interface between the CAN protocol controller and the physical bus. This device provides differential transmission capability to the bus and differential reception capability to the CAN controller, conforming to the "ISO11898" standard. System Structure This system is a motor control system based on the distributed fieldbus CAN bus for communication, using a DSP as the microcontroller. It combines the high-speed processing capabilities of the DSP with the high performance and high reliability of CAN bus communication, creating a distributed industrial control system. The system design is mainly divided into two parts: firstly, the execution component: LF2407-A controls motor movement; secondly, network communication: CAN enables distributed monitoring communication. The system architecture can be mainly divided into three layers: The first layer, the PC and CAN bus interface layer—realizes the visual operation and control between the PC and the CAN communication bus, implemented using the PC-CAN—an intelligent CAN bus communication adapter card; the second layer, the CAN bus and DSP controller LF2407 interface layer—realizes the physical interface and communication between the CAN bus and the CAN controller of the LF2407-A board; the third layer, the LF2407 I/O port and stepper motor drive interface—realizes the electrical isolation protection of the LF2407-A board and the high-current drive of the stepper motor, completing the actual motor action. The PC, as the host computer of the system, effectively utilizes its advantages of strong computing power, large capacity, and user-friendly interface. The PC-CAN is a high-performance, cost-effective intelligent CAN bus communication adapter card that allows the PC to easily connect to the CAN bus, enabling high-speed data exchange between the CAN bus and the host PC. The PC-CAN features built-in opto-isolation to protect the PC from damage due to ground loop current, enhancing the system's reliability in harsh environments. PCA82C250: An interface transceiver for the LF2407 embedded CAN controller and CAN bus. 8-pin, high-speed, up to 1Mbps transmission rate. It provides differential transmission capability to the CAN bus and differential reception capability to the CAN controller. Figure 5 shows the DSP 2407-A and stepper motor driver interface. The interface achieves electrical isolation between the DSP chip and the stepper motor, protecting the DSP chip's safety, and also completes the conversion from the DSP's weak output current (less than 10mA) to the large current (+1.5A) required for stepper motor drive, providing the necessary drive current for the motor. TLP521 is an opto-isolation coupler between the DSP and the stepper motor, providing level isolation, protecting the DSP chip, and completing signal conversion. RIF530 is a VMOS transistor, serving as the stepper motor drive current switch. CAN Bus Physical Layer: The physical link communication medium for CAN can be twisted pair, coaxial cable, or optical fiber. A non-destructive, priority-based bus arbitration method is used. In this system, twisted pair is used as the communication medium. Software Design The software design of this system is crucial for completing the distributed control system based on the CAN bus. Multi-machine communication on the CAN bus is implemented through software programming, enabling data reception and transmission. Two-node communication is implemented on two LF2407-A boards: one is the local node, receiving request data frames from the remote node and sending data frames; the other is the remote node, sending a request frame to request data transmission from the remote node. The main components are: 1. Overall Motor Control System – This involves system initialization, generating the motor control frequency signal, modifying the motor control word via interrupts, implementing motor speed control through a delay subroutine, and initializing the CAN module. 2. Sending a Remote Frame Request via CAN – This initializes the CAN request frame, designating CAN mailbox 3 as the send request frame mailbox and CAN mailbox 0 as the receive data frame mailbox. Mailbox 3 sends a request frame requesting motor control word data. When the receive message flag is found to be 1 (RMP=1), mailbox 0 receives the data. 3. Initializing an Automatic Response to a Remote Frame Request via CAN – This initializes the CAN automatic response to remote frame requests, designating CAN mailbox 3 as the send mailbox. When a remote request is received, a data frame is sent. The following is a flowchart of the software program for initializing an automatic response to a remote frame request using CAN, as shown in Figure 6. Figure 6: Flowchart of CAN Initialization of an Automatic Response to a Remote Frame Request. Conclusion This paper studies the composition and implementation of a distributed motor control system based on the CAN bus. Combining the high-speed processing capability of the DSP with the high reliability and stability of the CAN fieldbus provides a good solution for building a new type of real-time, fast-response distributed industrial control network. In particular, the embedded modules of this industrial control chip LF2407A—pulse width encoding (PWM), comparator unit (CMP), capture unit (CAP), and integral encoder pulse (QEP) unit—provide direct control applications for DC and AC motors, eliminating the need for extensive and tedious algorithm programming required in traditional microcontroller control systems, effectively accelerating the development and application of industrial control systems.