Controller Area Network (CAN)
The Controller Area Network (CAN) represents an essential vehicle bus standard. It was explicitly engineered to facilitate communication between microcontrollers and devices without resorting to a central computer. The primary purpose of CAN is to enhance vehicle interconnectivity and foster swift data exchange between various systems within the vehicle.
MCP2515
The MCP2515 is an integrated circuit produced by Microchip Technology, constructed to function as a stand-alone CAN controller. It exhibits compatibility with an SPI (Serial Peripheral Interface) which makes it versatile in various applications. Although its primary use is in automotive industries, it is also used in a variety of other control applications.[1]
The MCP2515 bridges the connection between the CAN protocol and the SPI protocol by receiving CAN messages and translating them into SPI data, allowing the microcontroller to interpret the information. Similarly, it transforms SPI data into CAN messages for transmission.[2]
The MCP2515's operational details include its capacity to support CAN 2.0A and B, drawing attention to its alignment with established CAN standards and equipping it for both basic and extended frame format usage.[3]
Applications
The python-can library provides Controller Area Network support for Python, providing common abstractions to different hardware devices, and a suite of utilities for sending and receiving messages on a CAN bus.
There is an example of an installation on Jetson_Orin here.
Pi4
Raspberry Pi offers an easy to deploy 2-Channel Isolated CAN Bus Expansion HAT which allows to quickly integrate it to the peripheral devices. See the tutorial for more information
Arduino
Arduino has a good support of the MCPs with many implementations of the drivers
MCP2515 Driver
By default the CAN bus node is supposed to acknowledge every message on the bus weather or not that node is interested in the message. However, the interference on the network can drop some bits during the communication. In the standard mode, the node would not only continuously try to re-send the unacknowledged messages, but also after a short period it would start sending error frames and then eventually go to bus-off mode and stop. This causes sever issues when the CAN network works with multiple motors.
The controller has a one-shot setup that requires changes in the driver.
Wiring
Here is some suggested equipment for wiring a CAN bus:
- Molex Mini-Fit Junior connectors
- CAN bus cable
- Heat shrink
References
- ↑ MCP2515 Stand-Alone CAN Controller with SPI Interface. Microchip Technology. Official datasheet.
- ↑ MCP2515 Stand-Alone CAN Controller with SPI Interface. Microchip Technology. Official datasheet.
- ↑ MCP2515 Stand-Alone CAN Controller with SPI Interface. Microchip Technology. Official datasheet.
