Gd32f4xx MCU drives MCP2515 to expand can interface

1、GD32F4xx SPI

GD32F4xx Series of MCU Only 2 individual CAN Interface , If more CAN Interfaces are mostly used mcp2515 The chip performs SPI turn CAN Interface to use . Let's first introduce GD32F4xx MCU Of SPI peripherals .

1.1 SPI brief introduction

SPI (Serial Peripheral Interface, Serial peripheral interface ), Provides the basis for SPI Data sending and receiving function of the protocol , It can work in master or slave mode .
SPI It's a synchronous data bus , That is, it uses a separate data line and a separate clock signal , To ensure the synchronization between the sender and the receiver . The clock signal tells the receiver to sample the signal on the data line at the exact time . The side that provides the clock signal is called the host （Master）, The other side is the slave （slave）. In the use of SPI When communication , There is usually only one host , But it can be controlled by multiple slaves . The data acquisition time can be the rising edge or falling edge of the clock signal .

1.2 SPI Pin

Pin name	Direction	describe
SCK	Input / Output	host ：SPI Clock output ; Slave ：SPI Clock input
MISO	Input / Output	host ： Data receiving line ; Slave ： Data transmission line
MOSI	Input / Output	host ： Data transmission line ; Slave ： Data receiving line
NSS	Input / Output	Software NSS Pattern （ That is, through other IO The port controls the slave CS Pin ）： Don't use ; from