SPI只能读取16位数据的后8位

发布于 2020-03-29 20:52:21 浏览：1558 订阅该版

使用 rt-thread SPI 架构读取 adis16475 六轴传感器的数据，传感器SPI时序及配置如下
![1_adis.png](/uploads/202003/29/204520akgo3ktazagjh6n4.png)

![2_adis.png](/uploads/202003/29/204929r06ua5wc055q9pp5.png)

代码配置如下
``` {
 struct rt_spi_configuration cfg;
 cfg.data_width = 16;
 cfg.mode = RT_SPI_MODE_3 |RT_SPI_MASTER| RT_SPI_MSB; /* SPI Compatible: Mode 0 and Mode 3 */
// cfg.max_hz = 1 * 1000 * 1000; /* 1M */
				 cfg.max_hz = 1000 * 1000;
 rt_spi_configure(spi_dev_adis16475, &cfg);
 }
				
			rt_uint8_t res = RT_EOK; 
			 
			rt_uint16_t adis16475_read_id = 0x7200;
			rt_uint16_t msc_ctrl_reg = 0x6000;
			rt_uint16_t up_scale_reg = 0x6200;
			rt_uint16_t null_cfg_reg = 0x6600;
			 
//				rt_uint8_t adis16475_read_id[2] = {0x72, 0};
 rt_uint8_t id[16] = {0};
			 
 
 /* 方式1：使用 rt_spi_send_then_recv()发送命令读取ID */
 res = rt_spi_send_then_recv(spi_dev_adis16475, &adis16475_read_id, 2, id, 4);
			 if (res != RT_EOK)
					rt_kprintf("adis16475_read_id failed!");
			 res = rt_spi_send_then_recv(spi_dev_adis16475, &msc_ctrl_reg, 2, &id[4], 4);
			 if (res != RT_EOK)
					rt_kprintf("msc_ctrl_reg failed!");
	 res = rt_spi_send_then_recv(spi_dev_adis16475, &up_scale_reg, 2, &id[8], 4);
			 if (res != RT_EOK)
					rt_kprintf("up_scale_reg failed!");
 res = rt_spi_send_then_recv(spi_dev_adis16475, &null_cfg_reg, 2, &id[12], 4);
			 if (res != RT_EOK)
					rt_kprintf("null_cfg_reg failed!");
 
 rt_kprintf(" use rt_spi_send_then_recv() read adis16475 ID is: 0x%08x, msc_ctrl: 0x%08x, up_scal: 0x%08x , null_cfg: 0x%08x, reg: 0x%04x ", 
				* (rt_uint32_t *)id, * (rt_uint32_t *)&id[4], * (rt_uint32_t *)&id[8], * (rt_uint32_t *)&id[12], * (rt_uint16_t *)&adis16475_read_id);

// /* 方式2：使用 rt_spi_transfer_message()发送命令读取ID */
       
       struct rt_spi_message msg1, msg2;
				rt_uint8_t adis16475_id_reg[2] = {0, 0x72};
				rt_uint8_t id2[4] = {0};
				rt_uint8_t id4[4] = {0};
				
       msg1.send_buf   = adis16475_id_reg;
       msg1.recv_buf   = id4;
       msg1.length     = 2;
       msg1.cs_take    = 1;
       msg1.cs_release = 0;
       msg1.next       = &msg2;

msg2.send_buf   = RT_NULL;
       msg2.recv_buf   = id2;
       msg2.length     = 4;
       msg2.cs_take    = 0;
       msg2.cs_release = 1;
       msg2.next       = RT_NULL;

rt_spi_transfer_message(spi_dev_adis16475, &msg1);
 rt_kprintf("use rt_spi_transfer_message() read adis16475 ID is: 0x%08x， 0x%08x ", * (rt_uint32_t *)id2, * (rt_uint32_t *)id4);
 
 rt_uint16_t get_id = rt_spi_sendrecv16(spi_dev_adis16475, 0x72);
		 rt_kprintf("use rt_spi_sendrecv16 read adis16475 ID is: 0x%04x ", get_id);
	
			 rt_uint8_t id3[5] = {0};
 rt_spi_send(spi_dev_adis16475, adis16475_id_reg, 2);
 rt_spi_recv(spi_dev_adis16475, id3, 2);
 rt_kprintf("use rt_spi_send read adis16475 ID is: 0x%08x ", * (rt_uint32_t *)id3);```读取的ID 位0x005b, 正常的应该为0x405b, 前面的0x40 数据丢失，其他的寄存器数据也类似； 如上面的代码所示，使用了多种读取方式，
![3.png](/uploads/202003/29/204941gnsa7zz4pq57a4qp.png)![3.png](/uploads/202003/29/204941gnsa7zz4pq57a4qp.png)

请问下有人遇到过类似的情况吗？