说明：  在STM32下面实现SPI驱动，关于RC531的几种SPI总线驱动，包括软件模拟实现SPI和硬件实现SPI接口，具有参考价值。
(STM32 implementation in the following SPI driver, on the RC531 several SPI bus driver, including software simulation and hardware implementation to achieve SPI SPI interface, with the reference value.)