RTT学习之SPI设备

SPI分为主、从、设备；具体又分标准SPI/DUAL SPI/QUAD SPI(用80字节的RAMrt_err_t rt_spi_take_bus(struct rt_spi_device *device);代替收发寄存器）

从设备的操作：在多线程通讯中，从机需要先获得SPI总线、CS使能；使用完后再分别释放，从而使其它获得控制权。

   rt_err_t rt_spi_take_bus(struct rt_spi_device *device);

   rt_err_t rt_spi_take(struct rt_spi_device *device)；

   rt_err_t rt_spi_release(struct rt_spi_device *device)；

   rt_err_t rt_spi_release_bus(struct rt_spi_device *device);

  void rt_spi_message_append(struct rt_spi_message *list, struct rt_spi_message *message);//单链表发送一条消息

二 主设备的操作：

2.1 先挂载已经注册好的SPI设备，

   rt_err_t rt_spi_bus_attach_device(struct rt_spi_device *device, const char *name, const char *bus_name, void *user_data)

  rt_err_t rt_hw_spi_device_attach(const char *bus_name, const char *device_name, GPIO_TypeDef* cs_gpiox, uint16_t cs_gpio_pin);//STM32的BSP操作

2.2然后利用配置结构体进行SPI设备的配置

   rt_err_t rt_spi_configure(struct rt_spi_device *device, struct rt_spi_configuration *cfg)

   rt_err_t rt_qspi_configure(struct rt_qspi_device *device, struct rt_qspi_configuration *cfg);//QSPI配置有专门的结构体。

 2.3SPI设备的读写操作：  

　　struct rt_spi_message {

　　const void *send_buf; /* 发送缓冲区指针 */

　　void *recv_buf; /* 接收缓冲区指针 */

　　rt_size_t length; /* 发送 / 接收 数据字节数 */

　　struct rt_spi_message *next; /* 指向继续发送的下一条消息的指针 */

　　unsigned cs_take : 1; /* 片选选中 */

　　unsigned cs_release : 1; /* 释放片选 */

}; 

函数	描述
rt_device_t rt_device_find(const char* name);	根据 SPI 设备名称查找设备获取设备句柄
struct rt_spi_message *rt_spi_transfer_message(struct rt_spi_device *device,struct rt_spi_message *message)；	自定义传输数据，结束时释放片选
rt_size_t rt_spi_transfer(struct rt_spi_device *device, const void *send_buf, void *recv_buf, rt_size_t length);	传输一次数据
rt_size_t rt_spi_send(struct rt_spi_device *device, const void *send_buf, rt_size_t length)	发送一次数据
rt_size_t rt_spi_recv(struct rt_spi_device *device, void *recv_buf, rt_size_t length);	接受一次数据
rt_err_t rt_spi_send_then_send(struct rt_spi_device *device, const void *send_buf1, rt_size_t send_length1, const void *send_buf2, rt_size_t send_length2);	连续两次发送
rt_err_t rt_spi_send_then_recv(struct rt_spi_device *device, const void *send_buf, rt_size_t send_length, void *recv_buf, rt_size_t recv_length);	先发送后接收

     rt_size_t rt_qspi_transfer_message(struct rt_qspi_device *device, struct rt_qspi_message *message);//QSPI操作

    rt_err_t rt_qspi_send_then_recv(struct rt_qspi_device *device, const void *send_buf, rt_size_t send_length, void *recv_buf, rt_size_t recv_length);//QSPI操作

    rt_err_t rt_qspi_send(struct rt_qspi_device *device, const void *send_buf, rt_size_t length)；//QSPI操作

   SPI 设备管理模块还提供 rt_spi_sendrecv8() 和 rt_spi_sendrecv16() 函数，这两个函数都是对原函数的封装