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How to create and run the first FreeRTOS application on the VisionSOM-RT

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How to create and run the first FreeRTOS application on the VisionSOM-RT


This article describes how to create and run first FreeRTOS application on the VisionSOM-RT module with the NXP i.MX RT1052 microcontroller. The application will be executed from the external QSPI Flash memory.


Requirements

Hardware

Software

  • Any terminal application, for example Termite

Importing the SDK

The created SDK needs to be imported to the MCUXpresso IDE. We can do it by selecting the import archive option in the Installed SDKs window, or by simple drag-and drop the archive file to this window.

VisionSOM-RT the first FreeRTOS application sdk1.png


VisionSOM-RT the first FreeRTOS application sdk2.png


VisionSOM-RT the first FreeRTOS application sdk3.png

Generating a new project

The MCUXpresso contains a project creator tool that allows to configure a new project with the software componenst available in the imported SDKs. The project creator is available in the File menu (File→New→Project…).


VisionSOM-RT the first FreeRTOS application project1.png


The project appropriate type is the New C/C++ Project.


VisionSOM-RT the first FreeRTOS application project2.png


Next, a target microcontroller should be selected.


VisionSOM-RT the first FreeRTOS application project3.png


In the next window we can set the name of the project, select the device package and the required software components and drivers. The project requires the FreeRTOS system and the following drivers:

  • clock
  • common
  • gpio
  • iomuxc
  • lpuart
  • xip-board
  • xip-device


VisionSOM-RT the first FreeRTOS application project4.png


In the next window we can configure the C library and the compiler options. This window also contains the available memories, so we need to define the Flash memory (Location 0x60000000, Size 0x1000000, Driver MIMXRT1050_SFDP_QSPI.cfx). The remaining parameters in this window may be configured with their default values.


VisionSOM-RT the first FreeRTOS application project5.png


After this step the project files should be created, but before we can compile it two more steps are required for proper QSPI Flash configuration. First of all we need to update the sources in the xip directory in order to support the QSPI flash. The updated version for this memory can be found on the NXP Community site in the QSPI_xip.zip archive.


The blog post:

https://community.nxp.com/community/mcuxpresso/mcuxpresso-ide/blog/2017/12/07/overview-of-using-the-mimxrt1050-evk-with-mcuxpresso-ide


The direct link to the archive:

https://community.nxp.com/servlet/JiveServlet/download/10894-1-430488/QSPI_xip.zip


We can simply remove all sources from the xip directory and put there the ones from the QSPI_xip.zip archive.


After that we also need to define the BOARD_FLASH_SIZE symbol, that is required in the xip/fsl_flexspi_nor_boot.h file. We can do it directly in the file or by creating a preprocessor symbol in the project configuration (C/C++ Build→Settings→Tool Settings→Preprocessor). The BOARD_FASH_SIZE symbol should be set according to the QSPI Flash size, which in our case is 0x1000000 (16MB).


VisionSOM-RT the first FreeRTOS application properties1.png


VisionSOM-RT the first FreeRTOS application properties2.png


Now we are able to build the project using the Build tool.


VisionSOM-RT the first FreeRTOS application build1.png

Configuring SEGGER tools

By default the installed SEGGER drivers support the external HyperFlash memories. In order to program the on-board QSPI Flash, the configuration files should be modified. The changes should be done in the JlinkDevices.xml file which can be found in the directories:

/opt/SEGGER/Jlink (Linux hosts)

C:\Program Files (x86)\SEGGER\JLink_V640 (Windows hosts – the driver version may be different)


In this file there is a section with the NXP iMXRT105x microcontroller family configuration, where each of the entries has a Loader value:

Devices/NXP/iMXRT105x/NXP_iMXRT105x_HyperFlash.elf

This value needs to be changed to:

Devices/NXP/iMXRT105x/NXP_iMXRT105x_QSPI.elf


The detailed information can be found on the SEGGER wiki page for the iMXRT1050 microcontrollers:

https://wiki.segger.com/I.MXRT1050

Running the example code

Now we have everything that is required to program the QSPI Flash memory and run the example. In order to do this we need to select the Debug using SEGGER J-Link probes option from the J-Link menu and choose the detected debug probe.


VisionSOM-RT the first FreeRTOS application debug1.png


VisionSOM-RT the first FreeRTOS application debug2.png


After the programming is done we will see the debug view of the MCUXpresso IDE.

VisionSOM-RT the first FreeRTOS application debug3.png

Configuring the GPIO

In our example we will use the blue LED (IO10) connected to the GPIO1_IO08 (GPIO_AD_B0_08) pin. We will configure it using the Pins configuration tool.


VisionSOM-RT the first FreeRTOS application pins1.png


In the configurator window we can select the proper pin and configure it as the GPIO output with Pull-down. We also need to create a label for it. In this example we will call it LED.


VisionSOM-RT the first FreeRTOS application pins2.png


When the configuration is done, we need to generate the source code using the Update project option.


VisionSOM-RT the first FreeRTOS application pins3.png


VisionSOM-RT the first FreeRTOS application pins4.png


After clicking OK, the source code for GPIO configuration will be generated in the board directory in or project.


We can do the same with the clock configuration, by opening the clock configuration tool and enabling 24MHz crystal input. This way we will create a default configuration for all clocks in the microcontroller. The Update project option will generate the source code in the board directory.


VisionSOM-RT the first FreeRTOS application clocks1.png


VisionSOM-RT the first FreeRTOS application clocks2.png

Configuring the LPUART

For the example we also need the LPUART port to communicate with the PC. On the VisionCB-RT-STD Carrier Board two microcontroller pins are connected to the FTDI USB-UART interface – GPIO_AD_B0_12 (LPUART1_TX) and GPIO_AD_B0_13 (LPUART1_RX). We can configure them using the pin configuration tool.


VisionSOM-RT the first FreeRTOS application uart1.png


We will also change the UART_CLK_ROOT clock frequency from 4MHz to 24MHz by changing its clock source to the OSC_CLK (external crystal oscillator). It will guarantee more accuracy during bit clock generation.


VisionSOM-RT the first FreeRTOS application uart2.png


Now we need to configure the LPUART1 peripheral. Again we can do it using the configuration tool for peripherals.


VisionSOM-RT the first FreeRTOS application uart3.png


In the configurator window we can select the configured peripherals and change their configuration. In the example we will use the default settings of the serial port (baud rate 115200, 8 data bits, 1 stop bit, no parity). The update option will generate the source code for us.


VisionSOM-RT the first FreeRTOS application uart4.png

FreeRTOS example

Now, when we have prepared the project and created all configurations, we can write a simple FreeRTOS example with two tasks: one for blinking LED and the second one for writing a string to the serial port. The source code of the example looks as follows:


#include <stdio.h>
#include "board.h"
#include "peripherals.h"
#include "pin_mux.h"
#include "clock_config.h"
#include "MIMXRT1052.h"
#include "fsl_gpio.h"
#include "fsl_lpuart.h"

#include "FreeRTOS.h"
#include "task.h"

TaskHandle_t ledTaskHandle;
TaskHandle_t uartTaskHandle;

void ledTask(void* param) {

	const TickType_t delayMs = 1000 / portTICK_PERIOD_MS;

	while(1) {
	    GPIO_PinWrite(GPIO1, 8, 1);
	    vTaskDelay(delayMs);
	    GPIO_PinWrite(GPIO1, 8, 0);
	    vTaskDelay(delayMs);
	}
}

void uartTask(void* param) {

	const TickType_t delayMs = 1000 / portTICK_PERIOD_MS;
	char text[32] = {0};
	uint8_t i = 0;

	while(1) {
	    sprintf(text, "HELLO TASK %d\r\n", i++);
	    LPUART_WriteBlocking(LPUART1, (uint8_t*)text, strlen(text));
	    vTaskDelay(delayMs);
	}
}

void main(void) {
    BOARD_InitBootPins();
    BOARD_InitBootClocks();
    BOARD_InitBootPeripherals();

    xTaskCreate(ledTask,  "LED_TASK",  128, NULL, 1, &ledTaskHandle);
    xTaskCreate(uartTask, "UART_TASK", 128, NULL, 1, &uartTaskHandle);

    vTaskStartScheduler();
}


It can be copied directly to the main.c file in the project.

Importing project

The configured project can be also imported directly to the MCUXpresso IDE. The project archive can be downloaded from this website and imported from the File→Import… menu.


VisionSOM-RT the first FreeRTOS application import1.png


In the import wizard we need to choose General→Existing Projects into Workspace.


VisionSOM-RT the first FreeRTOS application import2.png


Then in the next window we can choose the Select archive file option and browse to the downloaded zip archive.


VisionSOM-RT the first FreeRTOS application import3.png


After clicking Finish button the project sources will be copied to the active workspace. The SDK needs to be imported separately in order to compile and run the example.

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