SPI无法读取多个引脚电位的问题

发布于 2021-08-23 11:29:05 浏览：983 订阅该版

目前已经成功使用了SPI输出，是可以使用的。但是在SPI接收的时候出现了问题，电路如下：

![1.png](https://oss-club.rt-thread.org/uploads/20210823/277d02ca22bae959c5d0e550b55ec760.png.webp)

目前只能读取到一个输入口MI7，例如如果MI7为高电平，则读取结果为0xff，如果MI7为低电平，则读取结果为0X00，和MI0~MI6的电平没有任何关系。

使用逻辑分析仪的结果也是只有一个脉冲，但是代码用的是文档中的例程，只做了简单修改。如下：

![de377e1d22791e7868b461a2ffff970a.png.webp](https://oss-club.rt-thread.org/uploads/20210823/de377e1d22791e7868b461a2ffff970a.png.webp)

```c
include <rtthread.h>
include <rtdevice.h>
include "drv_spi.h"
include "drv_gpio.h"

define MI_CS_PIN   GET_PIN(3,4)     //  SPI接收的CS引脚，P304,

define RECV_SPI_DEVICE_NAME     "spi32"
struct rt_spi_device *spi_dev_recv; 
uint8_t recv = 0;

void rt_hw_spi_recv_init_entry(void *parameter)
{
		rt_thread_delay(1);
		rt_spi_recv(spi_dev_recv,&recv,1);
		rt_kprintf("spi_recv is 0x%x\n",recv);   
}

void rt_hw_spi_recv_init(void)
{
		rt_thread_t tid_recv;
		rt_err_t res; 
		res = rt_hw_spi_device_attach("spi3",RECV_SPI_DEVICE_NAME, MI_CS_PIN);             /* 绑定输入的CS片选引脚 */
		if(res != RT_EOK)
		{
				rt_kprintf("spi32 attach failed\n");
		}
		else
		{
			rt_kprintf("spi32 attach sucess\n");
		}
		spi_dev_recv = (struct rt_spi_device *)rt_device_find(RECV_SPI_DEVICE_NAME);  /* 查找spi设备获取设备句柄 */
		if (!spi_dev_recv)
		{
				rt_kprintf("spi sample run failed! can't find spi32 device!\n");
		}
		else
		{
				/* config spi */
				struct rt_spi_configuration cfg;
				cfg.data_width = 8;
				cfg.mode = RT_SPI_MASTER | RT_SPI_MODE_0 | RT_SPI_MSB; /* SPI Compatible: Mode 0 and Mode 3 */
				cfg.max_hz = 1 * 1000 * 1000; /* 1M */
				rt_spi_configure(spi_dev_recv, &cfg);
		}
		tid_recv = rt_thread_create("co_cfg", rt_hw_spi_recv_init_entry, RT_NULL, 1024, 21, 10);
		if (tid_recv != RT_NULL)
				rt_thread_startup(tid_recv);
}

INIT_APP_EXPORT(rt_hw_spi_recv_init);
```
想问一下各位大佬，有没有遇到过这样的问题。