ESP8266_RTOS_SDK Release v3.1.1

This is the list of changes since release v3.1.

1. Important Notes

• Fix an issue that device may fail to connect to router.

2. Changes in Functions and Features:

2.1 APP Update

• Add a feature to copy old RF parameters to the new SDK partition.

2.2 Build System

• Fix linking error when some functions' attribute is "unlikely".
• Fix an issue that combine binary overwrite checking may fail.
• Fix component nested issue
• Fix OTA firmware link address error

2.3 Driver

• Fix PWM jitter issue.

2.4 FreeRTOS

• Fix an issue that platform data may cause exception.
• Optimize FreeRTOS sleep module.
• Optimize FreeRTOS process efficiency.

2.5 Heap

• Fix an issue that sniffer may cause crash when read/write/erase flash.
• Fix an issue that heap functions may block Wi-Fi RX/TX in some cases.

2.6 LwIP

• Fix UDP send fail in some case.

2.8 System

• Fix delete "esp_timer" causing crash.
• Fix "abort" function cause critical error.
• Fix watch dog may be triggered when entering light sleep.
• Optimize the method to get APP information from partition table.

2.9 Wi-Fi

• Fix set phy mode error.
• Fix Wi-Fi software state machine mixed.
• Fix Wi-Fi connection broke in some cases.
• Fix clock error when init_data[112] = 1.
• Fix an issue that station gets AP information may cause system crash when it fails to connect to AP.
• Fix Wi-Fi connection broke issue when signal is weak.
• Fix header file dependence issue.
• Fix Wi-Fi disconnection fails in some case.

3. Tools

• Fix incorrect requirements modules for python.

4. Modified Documents

• Fix document format error for auto script of read the docs.
• Add gif to introduce FOTA work flow.