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标题: 【玩转多核异构】i.MX8M Plus开发板的M核SPI主从模式通讯 [打印本页]

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作者: 飞凌嵌入式    时间: 2023-4-7 10:30
标题: 【玩转多核异构】i.MX8M Plus开发板的M核SPI主从模式通讯

SPI（串行外围设备接口）是一种低成本、易使用的接口协议，具备全双工、高速、通讯简单的特点，被广泛应用于微控制器和外围设备芯片之间的通讯。当SPI接口作为主模式时可以连接Flash存储器、AD采样芯片、实时时钟RTC、LCD显示屏、音频芯片以及各种传感器。

随着产品功能的愈加丰富，多处理器使用SPI接口进行通讯的场景开始出现，而多个SPI设备之间通信必须由主设备(Master)来控制从设备(Slave)。

小编手上的OKMX8MP-C开发板基于NXP i.MX8M Plus多核异构处理器设计，它的M核有1路SPI，因而为实现SPI的相互通讯，我们就需要两块OKMX8MP-C开发板的SPI互作主从设备进行通信。本文小编就将从应用角度为大家讲解M核SPI间通讯的实现方式。

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1. SPI初始化

SPI初始化主要包括总线时钟、管脚和相应寄存器的初始化。具体如下：

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（1）SPI总线时钟：现将SPI总线倍频到800MHz，再10分频到80MHz。

1. <span class="hljs-selector-tag" style="box-sizing: border-box; color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;"="">CLOCK_SetRootMux</span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">(kCLOCK_RootEcspi2, kCLOCK_EcspiRootmuxSysPll1); </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">//SPI2总线时钟使用PLL1-800MHz </span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"=""><span class="hljs-selector-tag" style="box-sizing: border-box;" microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;"="">CLOCK_SetRootDivider</span><span microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">(kCLOCK_RootEcspi2, </span><span class="hljs-number" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(168,="" 46,="" 46);"="">2</span><span microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">U, </span><span class="hljs-number" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(168,="" 46,="" 46);"="">5</span><span microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">U); </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">//分频因子为2*5=10,设置SPI2总线时钟为80MHz</span></span>

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（2）管脚配置：选择SPI2的四个管脚。

1. <span class="hljs-selector-tag" style="box-sizing: border-box; color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;"="">IOMUXC_SetPinMux</span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">(IOMUXC_ECSPI2_MISO_ECSPI2_MISO, </span><span class="hljs-number" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(168,="" 46,="" 46);"="">0</span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">U); </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// SPI2-</span>

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（3）SPI速率：设置速率为500K。

1. #<span class="hljs-meta-keyword" style="box-sizing: border-box; border: 0px;">define</span> TRANSFER_BAUDRATE 500000U <span class="hljs-comment" style="box-sizing: border-box; border: 0px; color: rgb(153, 153, 153);">// 速率 500K</span>

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（4）数据长度选择：8bit。

1. <span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->burstLength = </span><span class="hljs-number" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(168,="" 46,="" 46);"="">8</span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 数据长度 8bit</span>

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（5）四种模式选择：CPOL和CPHA的四种组合即为SPI的四种模式。

1. <span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->clockInactiveState = kECSPI_ClockInactiveStateLow; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 时钟SCL: 活动时低电平，空闲时高电平 </span><div><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->dataLineInactiveState = kECSPI_DataLineInactiveStateLow; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 数据MOSI&MISO: 活动时低电平，空闲时高电平 </span></div><div><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->chipSlectActiveState = kECSPI_ChipSelectActiveStateLow; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 片选SS: 低电平选中，高电平无效 </span></div><div><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->polarity = kECSPI_PolarityActiveHigh; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 时钟信号极性，即CPOL为0的话 SCLK高电平有效(空闲的时候为低电平)，为1的话SCLK低电平有效(空闲的时候为高电平)。 </span></div><div><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->phase = kECSPI_ClockPhaseFirstEdge; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 时钟相位，即CPHA为0的话串行时钟的第一个跳变沿(上升沿或下降沿)采集数据，为1的话串行时钟的第二个跳变沿(上升沿或下降沿)采集数据。</span></div>

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（6）主模式选择：设置SPI为主模式。

1. <span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->channelConfig.channelMode = kECSPI_Master; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 主模式</span>

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（7）通道选择：一个 SPI 有四个硬件片选信号，每个片选信号是一个硬件通道，本程序选择通道0。

1. <span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">config->channel = kECSPI_Channel0; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 通道0</span>

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（8）关闭自回环：如果开启了自回环，那么SPI数据会在芯片内回环，不会到外部管脚，在程序调试时可以排除外部端子的干扰，但真实应用时，需要关闭自回环，从外部管脚收发数据。

1. <span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">Config->enableLoopBack = </span><span class="hljs-keyword" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(17,="" 75,="" 166);"="">false</span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">; </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">// 不回环，使用外部管脚</span>

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2. SPI收发流程

我们分别将两块OKMX8MP-C开发板命名为开发板1和开发板2，并且将开发板1的SPI接口采用主模式，使能收发中断；将开发板2的SPI接口采用从模式，使能收发中断。

SPI主发送64字节数据，SPI从接收后，将数据回传。SPI主接收回传信息后，比对接收和发送的数据是否一致，输出比对结果。如一致，本次传输结束，等待输入任何按键启动下一次传输。

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（1）SPI发送数据：EXAMPLE_ECSPI_MASTER_BASEADDR 表示为SPI2，g_m_handle为SPI实例，包含了发送接收中断及其回调函数，masterXfer为要发送的64字节数据。

1. <span class="hljs-selector-tag" style="box-sizing: border-box; color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;"="">ECSPI_MasterTransferNonBlocking</span><span style="color: rgb(100, 100, 100); font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;"="">(EXAMPLE_ECSPI_MASTER_BASEADDR, &g_m_handle, &masterXfer); </span><span class="hljs-comment" style="box-sizing: border-box; font-family: myFont, " microsoft="" yahei";="" font-size:="" 16px;="" text-align:="" justify;="" border:="" 0px;="" color:="" rgb(153,="" 153,="" 153);"="">//主模式中断方式发送数据</span>

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（2）SPI接收数据：SPI总线的发送和接收都是主模式控制的，因此接收函数的过程和发送是一致的。

（3）接收和发送数据对比：

1. <code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__keyword" style="outline: 0px; max-width: 1000%; color: rgb(202, 125, 55); box-sizing: border-box !important;">for</span> (i = <span class="code-snippet__number" style="outline: 0px; max-width: 1000%; color: rgb(14, 156, 229); box-sizing: border-box !important;">0</span>U; i < TRANSFER_SIZE; i++)  </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">{  </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">    <span class="code-snippet__keyword" style="outline: 0px; max-width: 1000%; color: rgb(202, 125, 55); box-sizing: border-box !important;">if</span> (masterTxData[i] != masterRxData[i])  </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">    {  </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">       errorCount++;  </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">    }  </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">}</span></code>

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( m# W' C1 x; ]二、SPI从模式

1. SPI初始化

SPI从模式初始化与主模式要保持一致，除了将工作模式设为从模式，其他设置均一样。主从模式选择：设置SPI为从模式。

1. config->channelConfig.channelMode = kECSPI_Slave; <span class="hljs-comment" style="box-sizing: border-box; border: 0px; color: rgb(153, 153, 153);">//从模式</span>

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2. SPI收发流程

开发板2的SPI接口采用从模式，使能收发中断。

SPI从进入等待接收状态，在片选有效后，通过接收中断获取数据，并回传信息，再次进入接收状态。

（1）SPI接收数据：EXAMPLE_ECSPI_SLAVE_BASEADDR表示为SPI2，g_m_handle为SPI实例，包含了发送接收中断及其回调函数，slaveXfer存储接收的数据。

1. <span class="hljs-selector-tag" style="box-sizing: border-box; border: 0px;">ECSPI_SlaveTransferNonBlocking</span>(EXAMPLE_ECSPI_SLAVE_BASEADDR, &g_s_handle, &slaveXfer); <span class="hljs-comment" style="box-sizing: border-box; border: 0px; color: rgb(153, 153, 153);">//从模式中断方式接收数据</span>

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（2）SPI发送数据：SPI总线的发送和接收都是主模式控制的，因此接收函数的过程和发送是一致的。

9 N5 f2 i# o; d9 O0 f+ w- x三、A核修改

A核设备树中若保留SPI2，内核解析设备树，在/dev下生成设备文件spidev1.0。这样待M核运行后，A核将重新对SPI2初始化，造成M核SPI功能异常，因此需要去除A核对SPI的控制。

1. 修改设备树

（1）在设备树OK8MP-C.dts中，删除SPI2设备节点相关信息。

1. <code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">&ecspi2 {  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__comment" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); font-style: italic; box-sizing: border-box !important;">    #address-cells = <1>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__comment" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); font-style: italic; box-sizing: border-box !important;">    #size-cells = <0>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    fsl,spi-num-chipselects </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <1>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    pinctrl-names </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> "default";  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    pinctrl-0 </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <&pinctrl_ecspi2 &pinctrl_ecspi2_cs>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    cs-gpios </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <&gpio5 13 GPIO_ACTIVE_LOW>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    status </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> "okay";  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    spidev1</span>:<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> spi@0 {  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">        reg </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <0>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">        compatible </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> "rohm,dh2228fv";  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">        spi-max-frequency </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <500000>;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">    };  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">};  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">
   
2. </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">
   0 c7 d5 G; k) }3 p' ]
3. </span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">pinctrl_ecspi2</span>:<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> ecspi2grp {  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">        fsl,pins </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">        MX8MP_IOMUXC_ECSPI2_SCLK__ECSPI2_SCLK       0x82  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">        MX8MP_IOMUXC_ECSPI2_MOSI__ECSPI2_MOSI       0x82  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">        MX8MP_IOMUXC_ECSPI2_MISO__ECSPI2_MISO       0x82  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">        >;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">};  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">pinctrl_ecspi2_cs</span>:<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> ecspi2cs {  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">    fsl,pins </span>=<span class="code-snippet__string" style="outline: 0px; max-width: 1000%; color: rgb(221, 17, 68); box-sizing: border-box !important;"> <  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">        MX8MP_IOMUXC_ECSPI2_SS0__GPIO5_IO13     0x40000  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__attr" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;">    >;  </span></span></code><code style="outline: 0px; max-width: 1000%; display: flex; position: relative;" liberation="" mono",="" menlo,="" courier,="" monospace;="" box-sizing:="" border-box="" !important;"=""><span class="code-snippet_outer" style="outline: 0px; max-width: 1000%; box-sizing: border-box !important;"><span class="code-snippet__meta" style="outline: 0px; max-width: 1000%; color: rgb(175, 175, 175); box-sizing: border-box !important;">};</span>  </span></code>

复制代码

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（2）编译生成新的内核镜像Image及设备树OK8MP-C.dtb。

（3）将生成的OK8MP-C.dtb和Image拷贝至开发板/run/media/mmcblk2p1/目录下，输入sync命令，重启开发板。

（4）输ls /dev查看发现没有SPI2设备文件spidev1.0。

7 N( x: X0 n+ K四、程序验证

1. 硬件连接

使用杜邦线将两块OKMX8MP-C开发板的SPI一一对应连接，线序如下：

开发板1--SPI主模式		开发板2--SPI从模式
管脚名称	开发板位置	管脚名称	开发板位置
MISO	P40-10	MISO	P40-10
MOSI	P40-8	MOSI	P40-8
SCK	P40-1	SCK	P40-1
SS0	P40-3	SS0	P40-3
GND	P40-4/P40-7	GND	P40-4/P40-7

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2. M核程序

修改uboot环境变量设置M核自启动，同时将M核程序forlinx_m7_tcm_firmware.bin

放到/run/media/mmcblk2p1/目录下。注意，SPI主模式程序须放入开发板1，SPI从模式程序须放入开发板2。

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3. 实际测试

（1）开发板2先上电，M核程序启动，完成SPI初始化后，进入接收等待状态；

（2）开发板1后上电，M核程序启动，完成SPI初始化后，主动发送64字节数据；

（3）开发板2的SPI接收数据，通过串口打印接收的数据，并将接收的数据再次发送；

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（4）开发板1的SPI接收到回传信息，通过串口打印接收的数据。和发送数据比对，输出结果。

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（5）此时在开发板1调试串口输入任意键，即可开启新一轮的SPI发送和接收流程。

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作者: ESCAPE    时间: 2023-4-7 11:21
SPI这个总线用的也很普遍，在控制外设中，是不可缺少的

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