FM1702SL射频芯片对外接口为SPI总线方式，对FM1702的操作实际上就是通过SPI总线

对FM1702SL内部的相关寄存器进行读写操作，从而实现射频读/写卡功能。本驱动程序基于FM2306A编写(兼容PIC指令集的其他MCU也同样试用)，通过IO口软件模拟SPI总线时序.-FM1702SL RF chip external bus interface for the SPI mode of operation of the FM1702 is actually through the SPI bus of the relevant internal FM1702SL register read and write operations, in order to achieve radio frequency read/write card. The driver is based on the preparation of FM2306A (PIC instruction set compatible with other MCU also tested), through the IO port SPI bus timing simulation software.