Esp32 things (V): analysis of common API of esp32 of Swiss Army knife

    in fact , All in esp32 It's used on the Internet api stay esp-idf You can find it all in the library , But for us, this is a big and comprehensive API Reference guide , At the beginning of the project , We don't have to spend too much time reading every API Use , Pick some commonly used API To study , Then query the reference documents according to the usage , Only in this way can we get twice the result with half the effort , So here are some common API Well ：

1、ESP_LOG

    The most instinctive thing for us to write a program is to log the key steps to the serial port terminal , In this way, you can see the implementation .

    1)、 stay ESP Please use... In the project of LOG API Print , Don't use it printf Isonudity api, In this way, you can turn on and off a specific level of... Through unified settings at different stages of the project LOG;

    2）、 Print LOG Please determine the level to be used , It's just Debug Information or error information , Because there are some levels LOG To be closed at the later stage of the project .

    ESP_LOGE -  Error log ( The minimum )

    ESP_LOGW -  Warning log

    ESP_LOGI -  Information level logs

    ESP_LOGD -  Log for debugging

    ESP_LOGV -  Log for prompt only { The highest )

2、vTaskDelay

    void vTaskDelay( portTickTypexTicksToDelay )

    call vTaskDelay() After the function , The task will go into a blocking state , The duration is determined by vTaskDelay() The parameters of the function xTicksToDelay Appoint , The unit is the system beat clock cycle . Constant portTICK_RATE_MS Used to help calculate the real time , This value is the cycle of the system beat clock interrupt , In milliseconds . In the file FreeRTOSConfig.h in , macro INCLUDE_vTaskDelay Must be set to 1, This function can be valid .

3、xTaskCreate

xTaskCreate( pdTASK_CODE pvTaskCode, const portCHAR * const pcName, unsigned portSHORT usStackDepth, void *pvParameters, unsigned portBASE_TYPE uxPriority, xTaskHandle *pvCreatedTask 

      Create a new task and add it to the task queue , Ready to run

The parameters are as follows ：

pvTaskCode

Entry function to the task . Tasks must be performed and never return ( namely ： Infinite loop ).

pcName

Describe the name of the task . It is mainly convenient for debugging . The maximum length is determined by configMAX_TASK_NAME_LEN. Definition

usStackDepth

Specify the size of the task stack , The number of variables that the stack can protect - Not the number of bytes . for example , If the stack is 16 Bit width ,usStackDepth Defined as 100, 200 byte , These will be allocated to the stack . Stack nesting depth （ Stack width ） Cannot exceed the maximum —— Contains size_t Variable of type

pvParameters

The pointer is used as a parameter to pass to the created task

uxPriority

Priority of the task when it runs ( 0 : The lowest priority )

pvCreatedTask

Used to pass a process —— Reference the created task