第 15 页 共 60 页
3.2.2 SPI to CAN mode
In this working mode, TD5(3)USPCAN always acts as SPI slave, SPI is limited to work in mode 3(CPOL and
CPHA are both 1), the data length is limited to 8 bits, and the MSB bits are transmitted first. Highest
communication rate under transparent conversion and transparent conversion with identification is 1.5Mbps,
and the highest communication rate of custom protocol conversion is 1Mbps.
The SPI can send data to the CAN bus terminal and receive data received by the CAN bus terminal. At
this time, the UART interface is invalid, and it will not process any data appearing in the UART interface, nor
will it return the data received by the CAN bus to the UART.
1. SPI frame
The data between the valid and invalid SPI chip selection is defined as one frame of data. Read data
and write data frames are defined in Figure 3.4 and Figure 3.5. There should be a time interval of 40us for
reading and writing buffer data between frames, as shown in Figure 3.6.
Figure 3.4 Schematic diagram of master reading data frame
Figure 3.5 Schematic diagram of master writing data frame
