This article mainly records the steps, problems and solutions of openharmony's GPIO lighting experiment;

Mainly follow Lian Zhian's tutorial: (6 messages) OpenHarmony lightweight system development [5] Driven GPIO lighting_Lian Zhian's blog-CSDN blog

I. Experimental steps

1. Create a new folder led_demo in the openharmony/code/master/master0805/applications/sample/wifi-iot/app directory;

And create a new led_demo.c file and BUILD.gn file in the led_demo folder;

2. Write led_demo.c program

#include  //unist.h is a built-in header file of the linux/unix system and contains many prototypes of unix system service functions#include "stdio.h"#include "ohos_init.h"#include "cmsis_os2.h" // Standard header file, connected to each CMSIS-RTOS2 compatible RTOS,// This file defines the interface to CMSIS-RTOS#include "iot_gpio.h" #define LED_TEST_GPIO 9 // for hispark_pegasus void *LedTask(const char *arg){//Initialize GPIOIoTGpioInit(LED_TEST_GPIO); // set as outputIoTGpioSetDir(LED_TEST_GPIO, IOT_GPIO_DIR_OUT); (void)arg;while (1){//output low levelIoTGpioSetDir(LED_TEST_GPIO, 0);//The first parameter is pin GPIO9, the second parameter is: 0 output, 1 inputusleep(300000);//output high levelIoTGpioSetDir(LED_TEST_GPIO, 1);usleep(300000);} } return NULL;} void led_demo(void){osThreadAttr_t attr; attr.name = "LedTask";//The current task nameattr.attr_bits = 0U;attr.cb_mem = NULL;attr.cb_size = 0U;attr.stack_mem = NULL;attr.stack_size = 512;//The size of a stack of the entire taskattr.priority = 26;//The current task priority,//osThreadsNew will create a thread that will execute the LedTask taskif (osThreadNew((osThreadFunc_t)LedTask, NULL, &attr) == NULL) {printf("[LedExample] Failed to create LedTask!\n");} } }SYS_RUN(led_demo);//Don't forget to add this line of code// The macro that comes with the SYS_RUN system is to tell the project that the entry function of the business code is led_demo

3. Write the BUILD.gn file in the led_demo folder

(note that the header file path on the third line is added later)

static_library("led_demo") {sources = ["led_demo.c"]include_dirs = ["//utils/native/lite/include","//kernel/liteos_m/components/cmsis/2.0","//base/iothardware/peripheral/interfaces/inner_api",]}

4. Modify the BUILD.gn file in the app directory

The first led_demo refers to the led_demo folder name;

The led_demo after the colon refers to the led_demo.c file, without the .c suffix (I personally understand it)

import("//build/lite/config/component/lite_component.gni")lite_component("app") {features = ["led_demo:led_demo",]}

5. Compile --> Burn

Second, problems encountered

Huawei Developer Forum

1, error: error: iot_gpio.h: No such file or directory

Cannot find iot_gpio.h header file

Reason: The version of the source code has changed (that is to say, when writing the BUILD.gn file in the led_demo folder, the path to add the header file is not the path provided by the source code of the previous version)

Solution: Enter find . -name iot_gpio.h to find the path to iot_gpio.h

Copy the found path to BUILD.gn;

Finally execute: hb build -f to compile