This is the list of changes since release v3.3.

1. Important Notes

• Removed aws-iot component and related example, if you need to implement aws-iot, please refer to https://github.com/espressif/esp-aws-iot.
• Removed ibm-mqtt component and related example, if you need to implement MQTT, please refer to https://github.com/espressif/esp-mqtt.
• Added support policy for each SDK version.
• Supported WPA3/PMF/802.11kv.
• Updated GCC to version 8.4.0, you can run ./install.sh in the root directory of RTOS SDK to install GCC and its related components.
• For security, with RTOS v3.4, if user sets a password to connect to an AP, then it cannot connect to an open AP with the same SSID.
• Supported SmartConfig V2 and provided example.

2. Changes in Functions and Features:

2.1 App Update

• Added App description section in the compiled firmware.

2.2 COAP

• Synced COAP component and example from ESP-IDF.
• Added examples of COAP multicast client and sever.

2.3 Driver

• Supported SPI Flash GD25Q64 QIO mode.
• Added API reference document for I2S.
• Removed i2s_bbpll_clk_enable since I2S clock is enabled by default during initialization.
• LEDC: Fixed PWM duty setting error.
• Supported float number in PWM.
• Optimized PWM hardware timer enable/disable, to ensure it will not be affected by other hardware drivers.
• Fixed an issue of ADC read.

2.4 ESP Common

• Added esp-common component, moved some common functions into it, synced from ESP-IDF.

2.5 ESP Event

• Added esp-event component.
• Optimized example to use esp-event APIs.

2.6 ESP HTTP Client

• Synced esp_http_client component and example from ESP-IDF.

2.7 ESP MQTT

• Synced esp-mqtt component and example from ESP-IDF.

2.8 ESP TLS

• Fixed an incorrect definition issue in example.
• Fixed a compiling error with mbedTLS.
• Fixed a wolfSSL_set_tlsext_host_name missing error when compiling with wolfSSL.

2.9 FatFS

• Added FatFS.

2.10 Free ModBus

• Added free-modbus.
• modbus protocol supports TCP transmission.

2.11 FreeRTOS

• Added a hardware detection for task stack overflow.
• Optimized interrupt workflow to speed it up.
• Added errno for thread safety.
• Added a feature to modify task stack depth dynamically.

2.12 Heap

• Added a configuration to enable/disable heap trace. If it is disabled, then malloc/free will be speeded up.
• Add integer overflow checks

2.13 LwIP

• Synced esp-lwip component and example from ESP-IDF.
• Added a configuration to enable auto-config for IPv6 address.
• Fixed an issue that system returns OK even if it actually fails to send data when ran out of Wi-Fi TX buffer.
• Increased the default TCP buffer size for sending data from 2880 bytes to 5760 bytes.
• Added an iperf example to test TCP/UDP throughput.
• Optimized the time that DHCP client needs to get an IP address.
• Supported enabling more LwIP debug log in menuconfig.
• Added IPv6 ICMP example.
• Fixed an issue of IPv6 multicast.

2.14 MbedTLS

• Fixed compiling error of unit test.
• Improved calculate speed of bignum.

2.15 mDNS

• Synced mDNS component and example from ESP-IDF.

2.16 System

• Supported print "%" with ets_printf.
• Supported GDB stub in panic.
• Added rtc uninitialized section and data uninitialized section.
• Fixed a deep sleep failure issue.
• Refactored ets timer to save memory.
• Supported link application firmware to the SPI flash's first 8MB space.
• Optimized compilation configuration, user can configure it by . ./export.sh.
• Added esp_random to get hardware random number.
• Fixed an issue of calling esp_restart.
• Changed the default frequency to be 160MHz since CPU starts.
• Added non-mask watchdog to monitor the system in critical section.
• Changed the task priority of app_main from 15 to be 1.
• Added fast boot mode, the system start-up time is about 20ms in this mode.
• Added a function to get the value of RTC hardware clock.
• Fixed a deep sleep time overflow issue.
• Fixed an issue of calling ets_printf when read/write SPI flash.
• Updated GCC to version 8.4.0.
• Disabled warning detection by default when compiling with cmake.
• Added a configuration to support 40MHz crystal oscillator.
• Fixed an issue of closing NMI
• Fixed an issue that the system may fail to wake up if set it deep sleep for a very short time (1~6us).

2.17 TCP Transport

• Synced TCP transport component and example from ESP-IDF.

2.18 TCPIP Adapter

• Added esp_netif_init and esp_netif_deinit to sync the same framework with ESP-IDF.
• Increased efficiency of getting an IP address by disabling power save function during DHCP.

2.19 Util

• Removed Util component, and move arithmetic codes into mbedtls component and esp8266 component.

2.20 VFS

• Synced VFS component from ESP-IDF to support FatFS.

2.21 Wear Levelling

• Added wear-levelling component for FatFS.

2.22 Wi-Fi

• Updated libphy.a to version 1163.0, which saved more memory and optimized Wi-Fi performance.
• Optimized Wi-Fi sleep arithmetic to save more power in modem/light sleep mode.
• Refactor softap sleep arithmetic to increase efficiency of sending data to station.
• Refactored MAC arithmetic of sending data to increase efficiency and save memory.
• Supported WPA3.
• Supported PMF.
• Supported PMF & ESP-NOW coexistence.
• Fixed a connecting fail issue of iPhone in ESP8266 softAP mode.
• Fixed a possible beacon attack issue during beacon auth mode change.
• Fixed a possible system restart issue when Wi-Fi and PWM are used at the same time.
• Fixed some ESP-Now issues.
• Supported getting frequency offset by scanning.
• Supported rssi info and phy mode in esp_wifi_sta_get_ap_info() api.
• Fixed an issue that softAP may fail to store PMK if system powers down unexpectedly.
• Fixed some Wi-Fi country code issues.
• Supported receiving multicast packets in ESP-NOW.
• Fixed an issue that Wi-Fi mode changed when enters deep sleep.
• esp_wifi_scan_start() returns error, if user calls it during station connecting to an AP.
• Fixed an issue that device will send 802.11 ACK even if sta or softap is stopped.
• Fixed an issue that softap checked dis-assoc packet sequence with data sequence.
• Fixed an issue that softap still does 4-way handshake when station tries to connect to it with wrong ssid.
• Refactored Wi-Fi connecting arithmetic to improve its performance if there are many APs with a same SSID but different passwords.
• Fixed an issue that device may receive packets which are forwarded by AP but originally sent by itself.
• Fixed an issue that device will rewrite flash even if sets the same station config.
• Supported 802.11kv, added Wi-Fi roaming example.
• Changed default DTIM in softAP mode from 2 to be 1.
• Added a configuration to set maximum and minimum packet length in sniffer mode.
• Improved the performance of catching packets in the air in sniffer mode.
• Fixed cipher mode error when scanning AP info.
• Optimized SmartConfig efficiency.
• Changed SmartConfig to use esp_event to sync status.
• For security, with RTOS v3.4, if user sets a password to connect to an AP, then it cannot connect to an open AP with the same SSID.
• Supported SmartConfig V2 and provided example.
• Fixed an issue that Wi-Fi RX buffer may fail to release with some specific router.
• Fixed connecting fail issues with some specific routers.
• Fixed an issue that if scanning more than 5 seconds then it will fail.
• Fixed an issue that if ESP8266 station connects to a router and also enables ESP-Now, its key pn will be updated incorrectly and Wi-Fi data may loss.
• Fixed a possible system crash issue when AMPDU registers were rewrote
• Fixed dump CCMP length error
• Fixed RF state error when scan again in scan callback function

2.23 Wi-Fi Provisioning

• Synced Wi-Fi Provisioning component and example from ESP-IDF.

2.24 WPA Supplicant

• Refactored WPA Supplicant to support WPA3, and keep the same framework with ESP-IDF.