With the implementation of the "smart manufacturing" slogan and the development of related industries, CAN bus is one of the three internationally recognized industrial buses, and it is used more and more in intelligent robots and new energy vehicles, but many engineers are in the project development process. I will encounter: What if the CAN interface is not enough?
An embedded or X86 industrial control board generally provides communication interfaces such as CAN, UART, Ethernet, USB, SPI, I2C, etc. However, due to processor limitations and meeting the versatility requirements, many manufacturers can only distribute them evenly. These interfaces, such as the interface of some industrial control core boards of Zhiyuan Electronics, are shown in Table 1:
Table 1 Details of the communication interface of the core board of Zhiyuan
It can be seen that the general-purpose core board generally provides 2 channels of CAN-bus, and the 2-way CAN-bus can effectively guarantee the general requirements, but in some special cases, especially in the new energy industry and the intelligent robot industry is growing. For example, in new energy vehicles, due to the increase in electrification and the increase in sensor technology, the body bus has changed from the previous two-way CAN (500K baud rate high-speed CAN and 250K baud rate low-speed CAN) to 4 channels. Even the demand for 5-way CAN. In this case, there is a new requirement for the CAN interface of the body ECU. What should be done if the CAN port of the traditional board is not enough?
figure 1
Figure 2 CSM300 module
Product Features of CSM300:
Two-way data communication between SPI or UART and CAN interface;
The CAN interface complies with the "ISO 11898-2" standard;
The maximum SPI rate can reach 1.5Mbit/s.
The maximum UART speed can reach 921.6kbps;
The maximum CAN speed can reach 1Mbit/s;
Isolation withstand voltage 2500VDC;
Working temperature: -40 ° C ~ +85 ° C.
The CSM300 (A) has three interfaces. One is the SPI interface, one is the UART interface, and the other is the CAN interface. Its pin arrangement is shown in Figure 3:
Figure 3 CSM300 pinout
Working mode of CSM300
Figure 4 SPI to CAN hardware circuit reference diagram
The UART to CAN mode, hardware circuit reference diagram shown in Figure 5, in this mode, CSM300 (A) can only send or receive data to the CAN bus terminal through the UART. The UART communication format is fixed as: 1 start bit, 8 data bits, 1 stop bit, and cannot be changed. The UART communication rate ranges from 300bps to 921600bps. In this mode, the SPI interface is invalid, will not process any data appearing on the SPI interface, and will not return the data received by the CAN bus to the SPI.
Figure 5 UART to CAN hardware circuit reference diagram
Data conversion mode
There are three types of data conversion methods for CSM300(A): transparent conversion, transparent tape identification conversion, and custom protocol conversion.
Transparent conversion mode: refers to any side of the bus as soon as it receives the data, it is immediately sent to the other side of the bus, the data is not processed. In the transparent conversion mode, the CSM300(A) does not need to perform additional processing on the data, which maximizes the data conversion speed and improves the buffer utilization, because the CSM300(A) is also converted and transmitted while receiving. The buffer that can be received is vacated.
Transparent tape identification conversion: Transparent tape identification conversion is derived from the transparent conversion, which means that the serial frame transmitted or received contains a valid CAN frame ID byte.
Figure 6 CSM300 Configuration Tool
In order to improve the user's development efficiency, the CSM300(A) series products are equipped with a dedicated CSM-Eval evaluation board, which can be used for configuration and testing of CSM300(A) products. Solve the problem of engineers' UART/SPI to CAN through comprehensive technical support.
Figure 7 CSM-Eval Evaluation Board
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