基于CH341的USB-CAN适配器设计

Design of USB-CAN adapter based on CH341

为便捷上位机访问工业现场CAN总线,提出了一种便携式即插即用的USB-CAN适配器设计方案。该适配器采用CH341作为USB总线转接芯片,直接把USB总线协议转化为并口协议;选用SJA1000芯片作为CAN控制器,支持CAN2.0B协议,以适应不同的CAN总线需求。系统从USB端口取电,且无需MCU/DSP介入,简化了电路结构;利用CH341主动并口功能,经相应的控制时序逻辑转换,上位机即可驱动SJA1000,进行CAN总线访问。该适配器支持上位机自主配置,灵活强,可靠性高。经实验测试,适配器支持访问不同的CAN总线网,速率可达1Mb/s。

In order to make the host to access CAN bus conveniently, a design scheme of portable plug-and-play USB- CAN adapter is presented. The adapter takes CH341 as a connection chip of USB to translate the UBS bus protocol into the parallel port one. SJA1000 chip is selected as the CAN controller to support CAN2.0B protocol, so as to adapt the needs of different CAN bus. The system gets power directly from USB without the intervention of MCU/DSP. Therefore, the electro- circuit becomes simple. The host can driver SJA1000 and access CAN bus by means of the active parallel port of CH341and relevant time sequence logic transfer. The adapter supports the active configuration of the host, and has high flexibility and reliability. The experiment results validate that the adapter has the ability to link all sorts of CAN buses, and its velocity can reach up to 1 Mb/s.