基于dsPIC30F4011的CAN转换器设计

摘要

现场总线（Field bus）是一种应用于生产现场，在现场设备与控制之间实行双向、串行、多节点数字通信的技术。但现场总线在协议标准上存在的差异给实践带来了影响，也影响了总线之间的开放性和互操作性。这种情况下，就需要利用接口转换器使不同总线之间互联。因此，本文针对传统的RS-485网络、RS-232网络与CAN总线网络之间的互联设计出RS-232/485/CAN与CAN接口转换器。

论文介绍了CAN总线与RS-232、RS-485和CAN接口转换器的设计与实现。主要从硬件设计和软件设计两个方面进行了论述。

首先，对现场总线技术和所要做到工作进行了简要的介绍，并介绍了CAN总线技术的基本原理和相关概念。

在硬件设计中，采用dsPIC30F4011作为微处理器，CAN总线通信接口采用英飞凌公司的芯片dsPIC30F4011作为CAN收发器。通过外围电路的设计实现了RS-232电平、RS-485电平和CAN总线电平信号的转换，单片机内集成的CAN控制器与CAN收发器dsPIC30F4011的互联。软件设计包括：单片机程序的编写，上位机CAN通信测试软件的编写。

关键字：CAN总线，RS-232，RS-485，协议转换，VC

Abstract

Fieldbus is the technology which is used to realize bidirectional, serial, multi-node digital communication between field device and field device, or control room. Field bus is used in manufacture field. The difference of field bus in protocol standard brings complexity to practice and influence the opening and interoperability of bus. In this case, it need protocol to interconnect traditional RS-485 network and CAN bus. It is used to data collecting system, through RS-232 interface it connects to computer and configures dynamically parameter of two buses.

Firstly, it gives brief introduction to the field bus technology and its related work. Secondly, it discourses on the basic principle and concept, the frame structure and anti-jamming analysis and measures of the CAN bus hardware. On this basis, it proposes the overall design of the system.

In hardware design, semiconductor company Infineon dsPIC30F4011 with a microprocessor, CAN bus communication interface, using Infineon’s dsPIC30F4011 as CAN transceiver, through the external circuit design to achieve the RS-232 levels to TTL level of conversion, the integrated single chip CAN controller connect with CAN transceiver dsPIC30F4011. Software design includes the preparation of microcontroller C programming language, and the programming of PC CAN communication test software.

Key words:CAN bus, RS-232, RS-485, Protocol transformer, VC