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NK-980IOT测评之QSPI

发布于 2022-03-28 00:11:42 浏览：1402 订阅该版

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## 开发环境简介

![IMG_20220326_205404.jpg](https://oss-club.rt-thread.org/uploads/20220327/e82c1348233c6dc1a133571e53382f8f.jpg.webp)

- NK-980IOT V1.0 (NUC980DK61Y)

- RT-Thread Studio + J-Link + VCOM

- U-Boot from SPI-NAND and rtthread running in DDR

## QSPI硬件介绍

### 概述

>The Quad Serial Peripheral Interface (QSPI) applies to synchronous serial data communication and allows full duplex transfer. Devices communicate in Master/Slave mode with the 4-wire bi-direction interface. The chip contains one QSPI controller performing a serial-to-parallel conversion on data received from a peripheral device, and a parallel-to-serial conversion on data transmitted to a peripheral device.
>
>The QSPI controller supports 2-bit Transfer mode to perform full-duplex 2-bit data transfer and also supports Dual and Quad I/O Transfer mode and the controller supports the PDMA function to access the data buffer.

QSPI适用于同步串行数据通信，允许全双工传输。QSPI的设备使用4线双向接口以主/从模式进行通信。NUC980芯片包含一个QSPI控制器，对从外围设备接收的数据执行串行到并行转换，并对传输到外围设备的数据执行并行到串行转换。

QSPI控制器支持2位传输模式以执行全双工2位数据传输，还支持双I/O和四I/O传输模式，控制器支持PDMA功能以访问数据缓冲区。

### 特性

>- Supports Master or Slave mode operation
>- Master mode up to 100 MHz and Slave mode up to 30 MHz (when chip works at VDD = 2.7~3.6V)
>- Supports 2-bit Transfer mode
>- Supports Dual and Quad I/O Transfer mode
>- Configurable bit length of a transaction word from 8 to 32-bit
>- Provides separate 8-level depth transmit and receive FIFO buffers
>- Supports MSB first or LSB first transfer sequence
>- Supports Byte Reorder function
>- Supports Byte or Word Suspend mode
>- Supports PDMA transfer
>- Supports 3-Wire, no slave selection signal, bi-direction interface
>- Supports one data channel half-duplex transfer
>- Supports receive-only mode

### 功能框图

![image-20220327195654406.png](https://oss-club.rt-thread.org/uploads/20220327/da393ab694ad78f88a603f562abf9397.png.webp)

### 硬件电路

![image-20220327195904041.png](https://oss-club.rt-thread.org/uploads/20220327/e9efc70439fd7e3b7b5ab428c86b83f1.png.webp)

由于开发板上的QSPI电路设计为复用形式，实际焊接芯片是一块NAND FLASH，型号为W25N01GVZE1G，因此关注上图绿框框内的部分即可。

## QSPI使用说明

1. 创建工程

使用RT-Thread Studio基于开发板傻瓜式创建项目，调试方式选择J-Link + JTAG：

![image-20220327203600578.png](https://oss-club.rt-thread.org/uploads/20220327/56a2a696d5275ef356b6015cab78b50d.png.webp)

2. 修改RT-Thread Settings
   去除掉模板工程中多余的配置和组件，只保留必要功能和QSPI(qspi0)外设：

![image-20220327204304939.png](https://oss-club.rt-thread.org/uploads/20220327/45795ccbd26655a973040724196e9a0e.png.webp)

编译运行并查看已经注册到系统里的设备是否有`qspi0`和`qspi01`：

![image-20220327204823545.png](https://oss-club.rt-thread.org/uploads/20220327/a14ef5ad28d08bd0b0a441c292eafd10.png)

从绿色的LOG中也可以看到，spinand_flash设备已经挂载到系统中了。
   
3. 代码简述
 - 底层浅析（以发送一个字节为例）
     QSPI数据传输的核心函数是位于`drv_qspi.c`设备驱动中的`nu_qspi_bus_xfer`，在该函数中会配置QSPI传输时的一些参数，然后调用`nu_spi_transfer`→`nu_spi_transmission_with_poll`（非DMA模式）→`nu_spi_write/nu_spi_read`函数来操作底层寄存器：
     ![image-20220327220608581.png](https://oss-club.rt-thread.org/uploads/20220327/3c2c7c713e323003c3078d25da19380e.png.webp)

再来翻一下手册：
     ![image-20220327221134575.png](https://oss-club.rt-thread.org/uploads/20220327/a3314438fc52aedc66e655cd1fc56259.png.webp)

又对上了，开心(*^▽^*)
     
 - 功能演示
   
      ![image-20220327222314510.png](https://oss-club.rt-thread.org/uploads/20220327/3ba5d331f9d8fec61cecd8ef33f3210b.png)
     
     如上图，rtthread和新唐分别提供了不同的MSH API用来访问QSPI NAND FLASH，简单演示一下：
   
     - nlist - 列出nand flash的所有分区信息：
   
       ![image-20220327222610178.png](https://oss-club.rt-thread.org/uploads/20220327/2fe52fa55000fe98bab9335a9a6d25f6.png)
   
     - nid - 查看nand flash的ID
   
       ![image-20220327222756093.png](https://oss-club.rt-thread.org/uploads/20220327/6237ace6fece1aab202485199c7b6684.png)
   
       和上电时识别到的一样。
   
     - mtd_nand read nand0 1 1 - 读nand0分区中block1, page1的数据：
   
       ![image-20220327223152264.png](https://oss-club.rt-thread.org/uploads/20220327/e0e7d698f532f6a4749554950cfc8109.png)
   
       从截取片段可以看出来，由于NAND FLASH中烧录了引导用的U-Boot，所以读出来的一些数据其实是位于U-Boot中的打印信息。
   
## 代码链接

[Gitee](https://gitee.com/charlesxsong/nuc980.git)

## 心得体会

QSPI+NAND FLASH的驱动做得非常完善，直接调用一些API即可访问设备、读写数据。

然而稍有不便的地方在于，RT-Thread Studio + J-LINK调试时只能使用U-BOOT引导在DDR里运行，并且单步debug时的跳转不是那么好用，跳来跳去容易误导人。