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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。 ![]() 0 g& @ u0 [8 O4 E$ V3 r/ j" w
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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。 ![]() ' m6 v8 S0 d" w4 H A! e
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4 K3 S' K: W7 ^0 Y, @5 h) f9 k一、SPI主模式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： , M4 o2 f. H1 D" z4 o
（1）SPI总线时钟：现将SPI总线倍频到800MHz，再10分频到80MHz。 - <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>
（2）管脚配置：选择SPI2的四个管脚。 - <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>
（3）SPI速率：设置速率为500K。 - #<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>
（4）数据长度选择：8bit。 - <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>
（5）四种模式选择：CPOL和CPHA的四种组合即为SPI的四种模式。 - <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>
3 A; a7 M. U$ b8 {（6）主模式选择：设置SPI为主模式。 - <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>
' o# {+ W% Y. _; ?* i U# h（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。 - <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>
（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。 - <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>
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。 ( K+ ^7 C* T& n& c
（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。 - <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>
0 ?+ @! z$ E9 Q) k2 U3 O M（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。
% a: Y# M! b' ?6 J& @（3）接收和发送数据对比： - <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>
- G, _; |2 Y5 q- {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。 - 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。 ) I# `/ s( A+ y9 G V% Q
（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。 - <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>
" ~ K( O9 x% c. `0 [（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。 . Q) o4 v- s- r1 G1 d9 `8 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。 # a6 p4 h$ e% L2 J% X
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。 - <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;">4 P4 R! n) K" L- `! w b' W
- </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;">3 E# L" h& n. ]# L
- </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>
（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。
! t& u7 Q2 o6 B, G9 t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。
8 D7 t& L+ p; y7 K! u7 v% R6 U3. 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； ![]() 6 K$ @) j2 A) M4 S" s2 b
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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。 ![]() % i6 Y L4 i4 g) u- X! ?' u
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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。 8 V+ Z% W* |8 X3 K; ~8 k O# j: M
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发表于 2023-4-7 10:30
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