Espressif Systems ESP Faq page 134

Chapter 4. Software framework
4.9.1 My application does not really need the watchdog timer, can I disable it?
There are two types of watchdog in ESP-IDF: task watchdog and interrupt watchdog. You can disable these two types
of watchdog in menuconfig. For more details, please refer to Watchdogs.
4.9.2 What are the differences between RTOS SDK and Non-OS SDK?
The main differences are as follows:
Non-OS SDK
• Non-OS SDK uses timers and callbacks as the main way to perform various functions - nested
events and functions triggered by certain conditions. Non-OS SDK uses the espconn network
interface; users need to develop their software according to the usage rules of the espconn interface.
RTOS SDK
• FreeRTOS SDK is based on FreeRTOS , a multi-tasking OS. You can use the standard FreeRTOS
interfaces to realize resource management, recycling operations, execution delay, inter-task mes-
saging and synchronization, and other task-oriented process design approaches. For the specifics
of interface methods, please refer to the official website of FreeRTOS or the book USING THE
FreeRTOS REAL TIME KERNEL-A Practical Guide.
• The network operation interface in RTOS SDK is the standard lwIP API. RTOS SDK provides
a package which enables BSD Socket API interface. Users can directly use the socket API to
develop software applications; and port other applications from other platforms using socket API
to ESP8266, effectively reducing the learning and development cost arising from platform switch.
• RTOS SDK introduces cJSON library whose functions make it easier to parse JSON packets.
• RTOS is compatible with Non-OS SDK in Wi-Fi interfaces, SmartConfig interfaces, Sniffer related
interfaces, system interfaces, timer interface, FOTA interfaces and peripheral driver interfaces, but
does not support the AT implementation.
4.9.3 Why does the log output ets_main.c when ESP8266 starts?
If ESP8266 prints ets_main.c when it starts, it indicates there are no programs that can be operated.
Please check the binary file and burn address if you encounter this issue.
4.9.4 Why do I get compile errors when using IRAM_ATTR in Non-OS SDK?
The default function attribute is IRAM_ATTR in Non-OS SDK. Therefore, if you want the function
to reside in IRAM, please leave out the ICACHE_FLASH_ATTR attribution in the function defini-
tion/declaration.
4.9.5 Where is main function in ESP8266?
• ESP8266 SDK does not provide main function. Main function is stored in first-stage bootloader in ROM,
which is used to load second-stage bootloader. The entry function of the second-stage bootloader is ets_main.
After startup, the user_init in the user application will be loaded to lead the user to the program.
Espressif Systems 117
Submit Document Feedback
Release master