异构多核处理器开发嵌入式应用入门

By Toradex Raul Rosetto Mu?oz

1). 简介

每天都有新的异构多核处理器/片上系统 SoC 面市。在 SoC 上集成微控制器和外设控制核正变得越来越普遍,看看最新发布的 NXP? :i.MX 6SoloX、i.MX7 和即将面世的 i.MX 8。在我看来,这有点像曾经 ADC(模数转换器)开始集成微处理器上的外设功能,在应用处理器上集成微控制器,可以解决 Linux 系统中一些实时可控相关的问题。

 

新技术的出现总是会引出许多问题,或许你会产生疑问,这是否需要很多工作量。本位旨在快速、明了地介绍一种使用异构多核方式开发应用的方法。这里我们将会涉及搭建开发环境以及创建一个双核通信的 ping pong 应用的基本步骤,最后演示一个用微控制器通过 SPI 读取 ADC 数据并把数据发送至运行 Linux 的处理器的实际应用。

 

这是揭示利用异构多核处理构架 SoC 开发嵌入式系统的系列文章。通过实际操作和一些案例演示,你可以快速地开始开发。

 

2). 硬件

本文中将使用 Toradex 双核 Colibri iMX7 计算机模块:该模块采用 NXP i.MX7 SoC,一个双核 ARM Cortex-A7 和 一个 ARM Cortex-M4 核心,A7 主频为 1GHz,M4 主频为 200MHz,同时具备 512MB 存储和 512MB 内存。模块如下图所示:

 

载板采用 Aster。这是 Toradex 新发布的产品,使新项目开发更加容易。该载板具有标准的 Arduino 接口,使开发人员能够利用市面上丰富的 Arduino 模块,缩减研发时间。除了 Arduino,还有一个兼容 Raspberry Pi 的接口,允许在开发的硬件上使用模块,不仅能够促进新产品的原型开发,也能够帮助从概念验证到可扩展、工业品质、保证生命周期硬件方案如 Toradex 的过渡。

 

3). 搭建开发环境

本文中演示的案例是在 Linux 电脑上开发的。所有 Cortex-M 上的代码都基于 Makefile 和 Cmake。你只需要安装少量的软件并正确配置编译工具链,就可以编译示例代码。

 

a). 我们建议使用 4.9 2015 Q3 版本 linaro toolchain。从这里下载好压缩包后,解压如下:

-------------------------------------------

tar xjf ~/Downloads/gcc-arm-none-eabi-4_9-2015q3-20150921-linux.tar.bz2

-------------------------------------------

b). 因为编译工具生成 32位应用,所以需要安装 32位的 libc 和 libncurse。在 Ubuntu 上,命令如下:

-------------------------------------------

sudo dpkg --add-architecture i386 sudo apt-get update sudo apt-get install libc6:i386 libncurses5:i386

-------------------------------------------

c). 现在可以测试编译工具:

-------------------------------------------

~/gcc-arm-none-eabi-4_9-2015q3/bin/arm-none-eabi-gcc –version

arm-none-eabi-gcc (GNU Tools for ARM Embedded Processors) 4.9.3 20150529 (release) [ARM/embedded-4_9-branch revision 227977] Copyright (C) 2014 Free Software Foundation, Inc.

This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

-------------------------------------------

d). 最后,安装 cmake 和 make:

-------------------------------------------

sudo apt-get install make cmake

-------------------------------------------

4). 下载示例

我们准备了一些示例,方便下载和测试,包括基本的 双核通信“Hello, World!”。下载源代码:

-------------------------------------------

$ git clone -b colibri-imx7-m4-freertos-v8 git://git.toradex.com/freertos-toradex.git freertos-colibri-imx7/

$ cd freertos-colibri-imx7/

-------------------------------------------

所有我们将会使用的源码都在这个文件夹里面。其中的文件已经能够支持 Colibri iMX7 和 FreeRTOS。在所有这些文件中,我们主要使用包含示例的的文件夹:

-------------------------------------------

[raul@localhost freertos-colibri-imx7]$ tree -L 2 examples/imx7_colibri_m4/

examples/imx7_colibri_m4/

├── board.c

├── board.h

├── clock_freq.c

├── clock_freq.h

├── demo_apps

│   ├── blinking_imx_demo

│   ├── hello_world

│   ├── hello_world_ddr

│   ├── hello_world_ocram

│   ├── low_power_imx7d

│   ├── rpmsg

│   └── sema4_demo

├── driver_examples

│   ├── adc_imx7d

│   ├── ecspi

│   ├── flexcan

│   ├── gpio_imx

│   ├── gpt

│   ├── i2c_imx

│   ├── uart_imx

│   └── wdog_imx

├── gpio_pins.c

├── gpio_pins.h

├── pin_mux.c

└── pin_mux.h

 

17 directories, 8 files

[raul@localhost freertos-colibri-imx7]$

-------------------------------------------

 

5). 搭建硬件环境

本文中,我们将不涉及如何调试 Cortex-M 的内容,我们使用 UART 打印固件的输出信息。了解如何搭建产品开发环境是十分重要的。由于 Cortex-M 和  Cortex-A 共享外设接口,你需要知道 UART B 被 Cortex-M 上的固件输出打印信息,UART A 则由 Cortex-A (U-boot and Linux) 使用。

 

异构多核处理器开发嵌入式应用入门_第1张图片

 

所以我们将使用 UART A 和 UART B。对于 UART A,在 Aster 上已经有 FTDI 芯片,可以直接连接 USB X4。该接口不仅用于给载板供电,还可以访问 UART-A, 所以当连接到电脑后,/dev/ttyUSBX 设备将会被自动识别。

 

对于 UART B, Colibri iMX7  的 TX 和 RX 引脚在 X20 扩展口上。因为没有 FTDI 或者 RS-232 转换器,你需要使用 FTDI 串口线。连接 RX、TX 和 GND 到 X20 的 第8、10、9 引脚。

 

异构多核处理器开发嵌入式应用入门_第2张图片

最后,图下图所示连接:

 

异构多核处理器开发嵌入式应用入门_第3张图片

现在都已经正确连接,在 Linux 使用 picocom 打开两个终端,打开串口:

 

终端 1:

-------------------------------------------

[raul@localhost ~]$ picocom -b 115200 /dev/ttyUSB0

-------------------------------------------

终端 2:

-------------------------------------------

[raul@localhost ~]$ picocom -b 115200 /dev/ttyUSB1

-------------------------------------------

 

6). 编译第一个示例

a). 进入 SPI 示例目录,编译第一个应用:

-------------------------------------------

[raul@localhost freertos-colibri-imx7]$ cd examples/imx7_colibri_m4/driver_examples/ecspi/ecspi_interrupt/master/

[raul@localhost master]$ ls armgcc hardware_init.c main.c

-------------------------------------------

b). 所有的示例都有 main.c 、hardware_init.c 和 armgcc 文件夹。我们先不解释源代码,只是进入目录,导出下载的 toolchain 路径然后编译:

-------------------------------------------

[raul@localhost armgcc]$ cd ..

[raul@localhost master]$ cd armgcc/

[raul@localhost armgcc]$ export ARMGCC_DIR=~/gcc-arm-none-eabi-4_9-2015q3/

[raul@localhost armgcc]$ ./build_all.sh

-- TOOLCHAIN_DIR: /home/raul/gcc-arm-none-eabi-4_9-2015q3/

-- BUILD_TYPE: Debug

-- TOOLCHAIN_DIR: /home/raul/gcc-arm-none-eabi-4_9-2015q3/

-- BUILD_TYPE: Debug

-- Could not determine Eclipse version, assuming at least 3.6 (Helios). Adjust CMAKE_ECLIPSE_VERSION if this is wrong.

-- The ASM compiler identification is GNU

-- Found assembler: /home/raul/gcc-arm-none-eabi-4_9-2015q3//bin/arm-none-eabi-gcc

-- Configuring done

-- Generating done

-- Build files have been written to: /home/raul/freertos-colibri-imx7/examples/imx7_colibri_m4/driver_examples/ecspi/ecspi_interrupt/master/armgcc

Scanning dependencies of target ecspi_interrupt_master_example

[  5%] Building C object CMakeFiles/ecspi_interrupt_master_example.dir/home/raul/freertos-colibri-imx7/platform/utilities/src/debug_console_imx.c.obj

...

...

...

[ 94%] Building C object CMakeFiles/ecspi_interrupt_master_example.dir/home/raul/freertos-colibri-imx7/platform/drivers/src/uart_imx.c.obj

[100%] Linking C executable debug/ecspi_interrupt_master_example.elf

[100%] Built target ecspi_interrupt_master_example

-- TOOLCHAIN_DIR: /home/raul/gcc-arm-none-eabi-4_9-2015q3/

-- BUILD_TYPE: Release

-- Eclipse version is set to 3.6 (Helios). Adjust CMAKE_ECLIPSE_VERSION if this is wrong.

-- Configuring done

-- Generating done

CMake Warning:

  Manually-specified variables were not used by the project:

 

    CMAKE_TOOLCHAIN_FILE

 

 

-- Build files have been written to: /home/raul/freertos-colibri-imx7/examples/imx7_colibri_m4/driver_examples/ecspi/ecspi_interrupt/master/armgcc

[  5%] Building ASM object CMakeFiles/ecspi_interrupt_master_example.dir/home/raul/freertos-colibri-imx7/platform/devices/MCIMX7D/startup/gcc/startup_MCIMX7D_M4.S.obj

...

...

...

[ 94%] Building C object CMakeFiles/ecspi_interrupt_master_example.dir/home/raul/freertos-colibri-imx7/platform/drivers/src/uart_imx.c.obj

[100%] Linking C executable release/ecspi_interrupt_master_example.elf

[100%] Built target ecspi_interrupt_master_example

[raul@localhost armgcc]$

 

         The binaries are located in the "release" directory.

[raul@localhost armgcc]$ cd release/

[raul@localhost release]$ ls

ecspi_interrupt_master_example.bin  ecspi_interrupt_master_example.hex

ecspi_interrupt_master_example.elf  ecspi_interrupt_master_example.map

[raul@localhost release]$

-------------------------------------------

在这里, bin 文件是最重要的。我们使用 U-boot 将其加载到 Cortex-M4。

 

7). 运行固件程序

为了运行固件程序,U-boot 需要加载这个二进制文件,然后在 Cortex-M 上运行。也可以用另外的方法。我的建议是使用 SD 卡或者网络。我们将会演示如何使用这两种方法。一方面,需要知道的是使用网络,开发将以动态的方式进行,因为不需要在载板上拔插 SD 卡。另一方面,为了使用以太网加载文件,你需要配置 tftp 服务器,我这里配置为 "/srv/tftp/"。参考 Flashing Linux Over Ethernet 了解 tftp 配置。

 

a). SD 卡:

复制文件到 SD 卡,然后放到载板上:

-------------------------------------------

[raul@localhost release]$ df

Filesystem              1K-blocks      Used Available Use% Mounted on

/dev/sdb1                 7780496    469540   7310956   7% /run/media/raul/DATA

[raul@localhost release]$ cp ecspi_interrupt_master_example.bin /run/media/raul/DATA

[raul@localhost release]$ umount /run/media/raul/DATA

-------------------------------------------

 

b). 以太网:

复制文件到 tftp 服务器目录,在载板上连接网线,配置好能够连接到电脑的网络。这里载板的 IP 是 192.168.0.170,电脑 IP 为 192.168.0.150。

-------------------------------------------

[raul@localhost release]$ cp ecspi_interrupt_master_example.bin /srv/tftp/

-------------------------------------------

 

c). 开启载板电源,上电的时候,在 UART-A (U-boot and Linux)  终端上按下任意按键。进入 U-boot,加载可执行文件。

 

./ SD 卡:

-------------------------------------------

Colibri iMX7 # fatload mmc 0:1 0x7F8000 ecspi_interrupt_master_example.bin

reading ecspi_interrupt_master_example.bin

9956 bytes read in 20 ms (485.4 KiB/s)

-------------------------------------------

./ 以太网:

 

Colibri iMX7 # tftp 0x7F8000 ecspi_interrupt_master_example.bin

Using FEC0 device

TFTP from server 192.168.0.150; our IP address is 192.168.0.170

Filename 'ecspi_interrupt_master_example.bin'. Load address: 0x7f8000

Loading: ################################################## 9.7 KiB

647.5 KiB/s

done

Bytes transferred = 9956 (26e4 hex)

-------------------------------------------

d). 加载完成后,无论是使用 SD 卡还是以太网,执行下面的命令运作已经加载到 Cortex-M 上的程序。

 

-------------------------------------------

Colibri iMX7 # dcache flush

Colibri iMX7 # bootaux 0x7F8000

## Starting auxiliary core at 0x007F8000 ...

Colibri iMX7 #

-------------------------------------------

e). 接下来,你应该可以看到在 UART B 终端上打印出 Cortex-M 的调试信息。你的屏幕如下图所示。

异构多核处理器开发嵌入式应用入门_第4张图片

f). 在 UART B 终端里按 “s”之前,试着将 SPI MISO 和 MOSI 连接起来。这样就可以看到在回环模式下的通信,不仅是发送数据,还可以接收 SPI 数据。

 

异构多核处理器开发嵌入式应用入门_第5张图片

-------------------------------------------

-------------- ECSPI master driver example --------------

This example application demonstrates usage of SPI driver in master mode.

It transfers data to/from remote MCU in SPI slave mode.

Press "s" when spi slave is ready.

MASTER: Transmited data: 1 :

Received data: 1

MASTER: Transmited data: 2 :

Received data: 2 ... ... ...

MASTER: Transmited data: 19 :

Received data: 19

MASTER: Transmited data: 20 :

Received data: 20

-------------------------------------------

 

8). 示例 - SPI

a). 在之前的示例中,我们只编译和执行了代码。现在我们将修改源码,实现同 Microchip MCP3008 的 SPI 通信。这个一个10位 ADC,具有8个输入。按下图连接到 Aster 和面包板:

异构多核处理器开发嵌入式应用入门_第6张图片

异构多核处理器开发嵌入式应用入门_第7张图片

异构多核处理器开发嵌入式应用入门_第8张图片

异构多核处理器开发嵌入式应用入门_第9张图片

 

b). 如果喜欢使用 Eclipse IDE,可以通过 CMake 生成 Eclipse 项目文件。 Cmake 的 -G 参数可以配置 “build system generator”。确保 build_all.sh 指定 “Eclipse CDT4 – Unix Makefiles”。

 

./ 在 armgcc 示例目录中:

-------------------------------------------

[raul@localhost armgcc]$ vi build_all.sh

#!/bin/sh cmake -DCMAKE_TOOLCHAIN_FILE="../../../../../../../tools/cmake_toolchain_files/armgcc.cmake" -G "Eclipse CDT4 - Unix Makefiles" -DCMAKE_BUILD_TYPE=Debug .

make -j4

cmake -DCMAKE_TOOLCHAIN_FILE="../../../../../../../tools/cmake_toolchain_files/armgcc.cmake" -G "Eclipse CDT4 - Unix Makefiles" -DCMAKE_BUILD_TYPE=Release .

make -j4

-------------------------------------------

./ 接下来运行 “build_all.sh”脚本:

-------------------------------------------

[raul@localhost armgcc]$ ./build_all.sh

[raul@localhost armgcc]$ ls .cproject .project

.cproject .project

-------------------------------------------

./ 打开 Eclipse 并导入项目

File > Import…

异构多核处理器开发嵌入式应用入门_第10张图片

./ 在 “Select root directory”,输入 “armgcc”文件夹目录

-------------------------------------------

/home/raul/freertos-colibri-imx7/examples/imx7_colibri_m4/driver_examples/ecspi/ecspi_interrupt/master/armgcc

-------------------------------------------

异构多核处理器开发嵌入式应用入门_第11张图片

./ 打开目录中的 main.c”文件

[TARGET] → [exec]ecspi_interrupt_master_example → Source Files

 

异构多核处理器开发嵌入式应用入门_第12张图片

./ 标准的示例是十分简单的。我们有必要介绍部分代码,从而在下面的示例中能够清楚地了解需要查看什么地方。

-------------------------------------------

int main(void)

{

    uint8_t control_char;

    uint8_t i;

 

    ecspi_init_config_t ecspiMasterInitConfig = {

        .baudRate = 500000,

        .mode = ecspiMasterMode,

        .burstLength = ECSPI_MASTER_BURSTLENGTH,

        .channelSelect = BOARD_ECSPI_CHANNEL,

        .clockPhase = ecspiClockPhaseSecondEdge,

        .clockPolarity = ecspiClockPolarityActiveHigh,

        .ecspiAutoStart = ECSPI_MASTER_STARTMODE

    };

 

    /* Hardware initialize, include RDC, CLOCK, IOMUX, ENABLE MODULE */

    hardware_init();

 

    /* Update clock frequency of this module */

    ecspiMasterInitConfig.clockRate = get_ecspi_clock_freq(BOARD_ECSPI_BASEADDR);

 

    PRINTF("\n-------------- ECSPI master driver example --------------\n\n\r");

    PRINTF("This example application demonstrates usage of SPI driver in master mode.\n\r");

    PRINTF("It transfers data to/from remote MCU in SPI slave mode.\n\r");

 

    /* Ecspi module initialize, include configure parameters */

    ECSPI_MasterConfig(&ecspiMasterInitConfig);

 

    /* Wait slave ready, then press 's' to start communication. */

    while(true)

    {

        PRINTF("Press \"s\" when spi slave is ready.\n\r");

        control_char = GETCHAR();

        if((control_char == 's') || (control_char == 'S'))

            break;

    }

    /* Send 1~20 to slave and receive data from slave */

    for(i = 0; i < 20; i++)

    {

        txData[0]++;

        ECSPI_MasterTransfer((uint8_t*)txData, (uint8_t*)rxData, 1);

        while(ECSPI_MasterGetTransferStatus());

        PRINTF("MASTER: Transmited data: %d \n\r", txData[0]);

        PRINTF("      : Received data: %d \n\n\r", rxData[0]);

    }

    while(1);

}

-------------------------------------------

./ 第一个需要注意的配置引脚复用的地方。这里我们将使用标准的 SPI。右击“hardware_init();”函数,选择“Open Declaration”

-------------------------------------------

void hardware_init(void)

{

    /* Board specific RDC settings */

    BOARD_RdcInit();

    /* Board specific clock settings */

    BOARD_ClockInit();

    /* initialize debug uart */

    dbg_uart_init();

 

    /* RDC ECSPI */

    RDC_SetPdapAccess(RDC, BOARD_ECSPI_RDC_PDAP, 3 << (BOARD_DOMAIN_ID * 2), false, false);

    /* Select board ecspi clock derived from OSC clock(24M) */

    CCM_UpdateRoot(CCM, BOARD_ECSPI_CCM_ROOT, ccmRootmuxEcspiOsc24m, 0, 0);

    /* Enable ecspi clock gate */

    CCM_EnableRoot(CCM, BOARD_ECSPI_CCM_ROOT);

    CCM_ControlGate(CCM, BOARD_ECSPI_CCM_CCGR, ccmClockNeededAll);

    /* Configure ecspi pin IOMUX */

    configure_ecspi_pins(BOARD_ECSPI_BASEADDR);

}

-------------------------------------------

./ 主要的硬件初始化和配置都在这个函数中完成。SPI 引脚的配置在最后一个函数“configure_ecspi_pins(BOARD_ECSPI_BASEADDR);”。

-------------------------------------------

void configure_ecspi_pins(ECSPI_Type* base)

{

         // ECSPI1 iomux configuration

         /* daisy chain selection */

         IOMUXC_ECSPI3_MISO_SELECT_INPUT = 0;  //(I2C1_SCL  SODIM 90)

         IOMUXC_ECSPI3_MOSI_SELECT_INPUT = 0;  //(I2C1_SCL  SODIM 90)

 

         /* iomux */

         IOMUXC_SW_MUX_CTL_PAD_I2C2_SCL = IOMUXC_SW_MUX_CTL_PAD_I2C2_SCL_MUX_MODE(3);    /* ECSPI SLK  */

         IOMUXC_SW_MUX_CTL_PAD_I2C1_SDA = IOMUXC_SW_MUX_CTL_PAD_I2C1_SDA_MUX_MODE(3);    /* ECSPI MOSI */

         IOMUXC_SW_MUX_CTL_PAD_I2C1_SCL = IOMUXC_SW_MUX_CTL_PAD_I2C1_SCL_MUX_MODE(3);    /* ECSPI MISO  */

         IOMUXC_SW_MUX_CTL_PAD_I2C2_SDA  = IOMUXC_SW_MUX_CTL_PAD_I2C2_SDA_MUX_MODE(3);     /* ECSPI SS0 */

 

         /* pad control */

         IOMUXC_SW_PAD_CTL_PAD_I2C2_SCL =    IOMUXC_SW_PAD_CTL_PAD_I2C2_SCL_PE_MASK  |

                            IOMUXC_SW_PAD_CTL_PAD_I2C2_SCL_PS(0)    |      /* pull down */

                            IOMUXC_SW_PAD_CTL_PAD_I2C2_SCL_DSE(0)   |

                            IOMUXC_SW_PAD_CTL_PAD_I2C2_SCL_HYS_MASK;

 

         IOMUXC_SW_PAD_CTL_PAD_I2C1_SDA = IOMUXC_SW_PAD_CTL_PAD_I2C1_SDA_DSE(0)   |

                            IOMUXC_SW_PAD_CTL_PAD_I2C1_SDA_HYS_MASK;

 

         IOMUXC_SW_PAD_CTL_PAD_I2C1_SCL = IOMUXC_SW_PAD_CTL_PAD_I2C1_SCL_HYS_MASK;

 

         IOMUXC_SW_PAD_CTL_PAD_I2C2_SDA  =  IOMUXC_SW_PAD_CTL_PAD_I2C2_SDA_PE_MASK   |

                            IOMUXC_SW_PAD_CTL_PAD_I2C2_SDA_PS(3)     |      /* pull up */

                            IOMUXC_SW_PAD_CTL_PAD_I2C2_SDA_DSE(0)    |

                            IOMUXC_SW_PAD_CTL_PAD_I2C2_SDA_HYS_MASK;

}

-------------------------------------------

./ 另外一个重要的文件是“board.h”。在同一个函数中,搜索 "configure_ecspi_pins (BOARD_ECSPI_BASEADDR);" 中的 "BOARD_ECSPI_BASEADDR",你将会发现部分“board.h”内容,这里配置除了 SPI 外的其他内容,例如中断向量表。

-------------------------------------------

/* Colibri SPI is ECSPI3 */

#define BOARD_ECSPI_RDC_PDAP                rdcPdapEcspi3

#define BOARD_ECSPI_CCM_ROOT                ccmRootEcspi3

#define BOARD_ECSPI_CCM_CCGR                ccmCcgrGateEcspi3

#define BOARD_ECSPI_BASEADDR                ECSPI3

#define BOARD_ECSPI_CHANNEL                 ecspiSelectChannel0

#define BOARD_ECSPI_IRQ_NUM                 eCSPI3_IRQn

#define BOARD_ECSPI_HANDLER                 eCSPI3_Handler

-------------------------------------------

./ 回到“main.c”我将改变主函数,获取 MCP3008 的数据。具体地讲,我们将读取芯片 channel 0 的数据。

-------------------------------------------

/* Wait slave ready, then press 's' to start communication. */

    while(true)

    {

        PRINTF("Press \"s\" when spi slave is ready.\n\r");

        control_char = GETCHAR();

        if((control_char == 's') || (control_char == 'S'))

            break;

    }

-------------------------------------------

./ 删除“break”,增加下面的代码。根据 MCP3008 白皮书,“00000001 10000000 00000000”序列分别表示起始位、通道选择和10位数据的信息。

-------------------------------------------

/* Wait slave ready, then press 's' to start communication. */

         while(true)

         {

                   PRINTF("Press \"s\" when spi slave is ready.\n\r");

                   control_char = GETCHAR();

                   if((control_char == 's') || (control_char == 'S'))

                   {

                            unsigned char datatx[3];

                            unsigned char datarx[3];

                            datatx[0] = 0b00000001;  //  first byte transmitted -> start bit

                            datatx[1] = 0b10000000; // second byte transmitted -> (SGL/DIF = 1, D2=D1=D0=0)

                            datatx[2] = 0b00000000; // third byte transmitted....don't care

 

                            /* SPI Read */

                            ECSPI_MasterTransfer((uint8_t*)&datatx[0], (uint8_t*)&datarx[0], 3);

                            while(ECSPI_MasterGetTransferStatus());

                            PRINTF("Transmited data: %d \n\r", datatx[0]);

                            PRINTF("Transmited data: %d \n\r", datatx[1]);

                            PRINTF("Transmited data: %d \n\r", datatx[2]);

                            PRINTF("Received data: %d \n\n\r", datarx[0]);

                            PRINTF("Received data: %d \n\n\r", datarx[1]);

                            PRINTF("Received data: %d \n\n\r", datarx[2]);

                            unsigned int a2dVal = 0;

                            a2dVal = (datarx[1]<< 8) & 0b1100000000; //merge data[1] & data[2] to get result

                            a2dVal |=  (datarx[2] & 0xff);

 

                            PRINTF("data = %d \n\n\r", a2dVal);

                   }

         }

-------------------------------------------

./ 修改完毕后,“int main (void)” 应该如下:

-------------------------------------------

int main(void)

{

         uint8_t control_char;

         uint8_t i;

 

         ecspi_init_config_t ecspiMasterInitConfig = {

                            .baudRate = 500000,

                            .mode = ecspiMasterMode,

                            .burstLength = ECSPI_MASTER_BURSTLENGTH,

                            .channelSelect = BOARD_ECSPI_CHANNEL,

                            .clockPhase = ecspiClockPhaseSecondEdge,

                            .clockPolarity = ecspiClockPolarityActiveHigh,

                            .ecspiAutoStart = ECSPI_MASTER_STARTMODE

         };

 

         /* Hardware initialize, include RDC, CLOCK, IOMUX, ENABLE MODULE */

         hardware_init();

 

         /* Update clock frequency of this module */

         ecspiMasterInitConfig.clockRate = get_ecspi_clock_freq(BOARD_ECSPI_BASEADDR);

 

         PRINTF("\n-------------- ECSPI master driver example --------------\n\n\r");

         PRINTF("This example application demonstrates usage of SPI driver in master mode.\n\r");

         PRINTF("It transfers data to/from remote MCU in SPI slave mode.\n\r");

 

         /* Ecspi module initialize, include configure parameters */

         ECSPI_MasterConfig(&ecspiMasterInitConfig);

 

         /* Wait slave ready, then press 's' to start communication. */

         while(true)

         {

                   PRINTF("Press \"s\" when spi slave is ready.\n\r");

                   control_char = GETCHAR();

                   if((control_char == 's') || (control_char == 'S'))

                   {

                            unsigned char datatx[3];

                            unsigned char datarx[3];

                            datatx[0] = 0b00000001;  //  first byte transmitted -> start bit

                            datatx[1] = 0b10000000; // second byte transmitted -> (SGL/DIF = 1, D2=D1=D0=0)

                            datatx[2] = 0b00000000; // third byte transmitted....don't care

 

                            /* SPI Read */

                            ECSPI_MasterTransfer((uint8_t*)&datatx[0], (uint8_t*)&datarx[0], 3);

                            while(ECSPI_MasterGetTransferStatus());

                            PRINTF("Transmited data: %d \n\r", datatx[0]);

                            PRINTF("Transmited data: %d \n\r", datatx[1]);

                            PRINTF("Transmited data: %d \n\r", datatx[2]);

                            PRINTF("Received data: %d \n\n\r", datarx[0]);

                            PRINTF("Received data: %d \n\n\r", datarx[1]);

                            PRINTF("Received data: %d \n\n\r", datarx[2]);

 

                            unsigned int a2dVal = 0;

                            a2dVal = (datarx[1]<< 8) & 0b1100000000; //merge data[1] & data[2] to get result

                            a2dVal |=  (datarx[2] & 0xff);

 

                            PRINTF("data = %d \n\n\r", a2dVal);

                   }

         }

}

-------------------------------------------

./ 重新编译,根据前面的示例通过 SD 卡或者以太网复制,执行二进制程序。

 

SD 卡:

-------------------------------------------

[raul@localhost release]$ df

Filesystem              1K-blocks      Used Available Use% Mounted on

/dev/sdb1                 7780496    469540   7310956   7% /run/media/raul/DATA

[raul@localhost release]$ cp ecspi_interrupt_master_example.bin /run/media/raul/DATA

[raul@localhost release]$ umount /run/media/raul/DATA

-------------------------------------------

以太网:

-------------------------------------------

[raul@localhost release]$ cp ecspi_interrupt_master_example.bin /srv/tftp/

-------------------------------------------

 

./ 将SD卡插入载板或者配置网络来执行编译好的二进制文件

SD 卡:

-------------------------------------------

Colibri iMX7 # fatload mmc 0:1 0x7F8000 ecspi_interrupt_master_example.bin

reading ecspi_interrupt_master_example.bin

9956 bytes read in 20 ms (485.4 KiB/s)

-------------------------------------------

以太网:

-------------------------------------------

Colibri iMX7 # tftp 0x7F8000 ecspi_interrupt_master_example.bin

Using FEC0 device

TFTP from server 192.168.0.150; our IP address is 192.168.0.170

Filename 'ecspi_interrupt_master_example.bin'.

Load address: 0x7f8000

Loading: ##################################################  9.7 KiB

          647.5 KiB/s

done

Bytes transferred = 9956 (26e4 hex)

-------------------------------------------

./ 一旦固件加载完毕,使用哪种方法就不再重要,执行下面命令运行 Cortex-M 上加载的程序。

-------------------------------------------

Colibri iMX7 # dcache flush

Colibri iMX7 # bootaux 0x7F8000

## Starting auxiliary core at 0x007F8000 ...

Colibri iMX7 #

-------------------------------------------

./ 现在使用修改后的代码,在 UART B 终端中按“s”将显示 channel 0 上模拟采集。

 

9). 同 Linux 之间的冲突

在使用这些 U-boot 命令之后,你或许想要在启动 Linux 后运行“boot”命令。现在的问题是,我们的示例使用了 UART B 和 the SPI。想要正常启动 Linux,就需要修改 device tree,让 Linux 不去使用这些资源。

 

你可以使用下面的命令,暂时关闭  UART B 和 SPI,而无需修改 device tree:

-------------------------------------------

Colibri iMX7 # setenv fdt_fixup 'fdt addr ${fdt_addr_r} && fdt rm /soc/aips-bus@30800000/spba-bus@30800000/serial@30890000  && fdt rm /soc/aips-bus@30800000/spba-bus@30800000/ecspi@30840000'

Colibri iMX7 # saveenv

Saving Environment to NAND...

Erasing NAND...

Erasing at 0x380000 -- 100% complete.

Writing to NAND... OK

-------------------------------------------

更多关于修改 device tree 的内容,可以参考 Toradex 开发者中心网站上的这篇文章。

 

10). 自动部署

在我的演示示例中,我通过以太网加载  Cortex-M 固件程序。一个节约时间的方法是自动复制文件到“/dev/tftp/”目录中。在项目的根目录中,打开文件:

-------------------------------------------

raul@localhost master]$ vi armgcc/CMakeLists.txt

-------------------------------------------

在最后面添加下面几行内容:

-------------------------------------------

[raul@localhost master]$ vi armgcc/CMakeLists.txt ADD_CUSTOM_COMMAND(TARGET ${Project_Name}_Main POST_BUILD COMMAND cp ${EXECUTABLE_OUTPUT_PATH}/ecspi_interrupt_master_example.bin /srv/tftp/m4.bin)

-------------------------------------------

再次运行 “./build_all.sh”脚本,如果使用 Eclipse 编译,你可以在“console”中看到自动执行的命令:

-------------------------------------------

cp /home/raul/freertos-colibri-imx7/examples/imx7_colibri_m4/driver_examples/ecspi/ecspi_interrupt/master/armgcc/release/ecspi_interrupt_master_example.bin /srv/tftp/m4.bin

-------------------------------------------

另外一个对我有帮助的优化是,在 U-boot 中创建自动加载固件程序的规则:

-------------------------------------------

Colibri iMX7 # setenv m4 'tftp 0x7F8000 m4.bin && dcache flush && bootaux 0x7F8000'

Colibri iMX7 # setenv bootcmd 'run m4; run ubiboot; setenv fdtfile ${soc}-colibri-${fdt_board}.dtb && run distro_bootcmd;'

-------------------------------------------

现在,每一次开启模块,就会自动加载固件程序然后运行 Linux。

 

11). 总结

在本文中,你可以掌握搭建异构多核处理器构架方案的基本步骤。通过两个演示示例,我们看到了如何在 Colibri iMX7 计算机模块的 HMP SoC Cortex-M4 核上编译和运行代码。我们也了解到 SoC 上的不同内核共享外设接口,所以你需要了解(以及规划)每个内核分配的外设。

你可能感兴趣的:(异构多核处理器开发嵌入式应用入门)